TERTIARY VOLCANIC ACTION 253
APPENDIX I—Mineral Resources 265
APPENDIX II—Palæontology of the Cretaceous Deposits 273
INDEX OF AUTHORS 287
GENERAL INDEX 289
LIST OF ILLUSTRATIONS
_To face
page_
PLATE I.— FIG. 1. On the Niger above Igbo 12
FIG. 2. Lokoja and Mt. Patti 12
PLATE II.— The Confluence of the Niger and the Benue 20
PLATE III.— FIG. 1. Abuja Rock 28
FIG. 2. Abuja Rock from the Walls of Abuja 28
PLATE IV.— FIG. 1. A Granite Mount near Abuja 48
FIG. 2. The Margin of the Nassarawa
Tableland from Jaginde 48
PLATE V.— FIG. 1. Worn Volcanic Cones near Awe 60
FIG. 2. The Wase Rock 60
PLATE VI.— FIG. 1. Yendam Hill, Yola Province 76
FIG. 2. Craters at Mboi 76
PLATE VII.— FIG. 1. Craters in the Mboi Hills 90
FIG. 2. A Crater in the Mboi Hills 90
PLATE VIII.— FIG. 1. Exfoliation in the Kilba Hills 104
FIG. 2. The Gorge of the Kaduna at Zungeru 104
PLATE IX.— FIG. 1. On the Summit of the Bauchi Plateau;
the Parade Ground at Bukuru 120
FIG. 2. On the Plateau looking Westward
from Bukuru 120
PLATE X.— FIG. 1. A Worn Volcanic Hill on the Bauchi
Plateau near Zamagan 134
FIG. 2. The Twin Cones of Kereng from Panyam 134
PLATE XI.— FIG. 1. Hillocks of Drift on the Bauchi
Plateau near Vom 152
FIG. 2. Hillocks of Drift to the West
of Naraguta 152
PLATE XII.— FIG. 1. A Granite Mount near Bauchi 170
FIG. 2. „ „ „ 170
PLATE XIII.— FIG. 1. The Sandstone Hills of Ture 190
FIG. 2. Ture or Tangale Peak 190
PLATE XIV.— FIG. 1. Dozi Hill, Kerri-Kerri 210
FIG. 2. A Trench-like Valley near Lele
in Kerri-Kerri 210
PLATE XV.— FIG. 1. Cretaceous Sandstones and Shales
at Awe 224
FIG. 2. A Flat-topped Hillock of Drift
above Naraguta 224
PLATE XVI.— Upper Benue Sandstones and Conglomerates
upon a Hummocky Granitic Floor 245
PLATE XVII.— FIG. 1. Inselberge Landscape around }
Abuja }
} _Frontispiece._
FIG. 2. Inselberge Landscape in }
Northern Yola }
PLATE XVIII.— FIG. 1. The Salt Fields of Awe; Volcanic
Hills in the Background 260
FIG. 2. Akiri Saltings 260
PLATE XIX.— Cretaceous Mollusca 286
PLATE XX.— „ „ 286
PLATE XXI.— „ „ 286
PLATE XXII.— „ „ 286
PLATE XXIII.— „ „ 286
PLATE XXIV.— „ „ 286
MAPS—
_To face
page_
I.—PRIMARY WATERSHEDS AND RIVER SYSTEMS 4
II.—THE BAUCHI PLATEAU AND THE NASSARAWA TABLELAND 40
III.—AXES OF ELEVATION 236
IV.—MINERAL RESOURCES 266
V.—COLOURED GEOLOGICAL AND TOPOGRAPHICAL MAP
AND SECTIONS _At end of Volume_
THE GEOLOGY AND GEOGRAPHY
OF NORTHERN NIGERIA
NORTHERN NIGERIA
CHAPTER I
PHYSICAL GEOGRAPHY
Introduction. Hydrographical systems; primary watersheds. The Niger:
Lokoja and Mount Patti; Jebba and the Juju Rock; the rapids of the
Niger. The Benue: the great plain of Muri; sandbanks. The Niger
Provinces: the tableland of central Kabba; domes and inselberge; the
plain of Ilorin; Borgu; Kontagora; typical scenery of crystalline and
sedimentary regions; the plains of Nupe; the sandstone plateaux of the
Niger. The Benue Provinces: Bassa and Nassarawa; the river belt of
sandstones; the Karshi hills and the Abuja Rock; the central plain; the
northern tableland; the plains of Muri; volcanic hills of the middle
Benue; the Wase Rock; the Murchison hills; the plateau of southern Yola;
the lower Gongola; volcanic craters and granite inselberge. The Central
Provinces: Zungeru and the gorge of the Kaduna; the plains and hills of
Zaria; the Bauchi plateau; the Ningi hills; Angass and Kanna; the
eastern plains; the Gongola valley; the cliffs of Tongolan; the Kudu
valley; the Gateri hills; Tangale and Waja; The Peak. The Northern
Provinces: southern Bornu; the Bima hills; the Barbur volcanic plateau;
the Tagum hills; eastern Bornu; firki land and blown sand; Lake Chad;
the central plains of Bornu; the Kerri Kerri plateau; intersecting
trench-like valleys; the plains of Katagum; Kano; Mounts Dala and Kogon
Dutsi; Kazaure; Katsina; Sokoto; the Gulbin Kebbi; dallols and dissected
sandstone plateaux.
The Protectorate of Northern Nigeria comprises an area of about 255,700
square miles, of which the greater part is enclosed within the obtuse
angle formed by the Niger with its great tributary the Benue. The north-
eastern corner is occupied by Lake Chad, whence irregular lines forming
the northern and eastern boundaries between the Protectorate, the French
Sudan and the Kameruns run west and south respectively to the Niger and
the Benue. Within the oblique figure thus formed lie the provinces of
Sokoto, Kano, Bornu, Bauchi, Zaria, Kontagora, Nupe, Nassarawa and
portions of Muri and Yola. West of the Niger lie Borgu, Ilorin and
Kabba, which adjoin Dahomey and Southern Nigeria, while south of the
Benue lie Bassa and parts of Muri and Yola, marching with Southern
Nigeria and the Kameruns. The administrative headquarters of the
Protectorate are at present fixed at Zungeru on the Kaduna in western
Zaria, while the subordinate headquarters of the fourteen provinces
enumerated above are located respectively at Sokoto, Kano, Maidugari,
Bauchi, Zaria, Kontagora, Bida, Keffi, Ibi, Yola, Kiama, Ilorin, Lokoja,
and Dekina. Lokoja also, in addition to being the headquarters of Kabba
province, is from its situation at the confluence of the Niger and the
Benue the natural emporium of European commerce.
Many of the more striking physical features of the Protectorate are now
comparatively well known. The Niger with its flat-topped sandstone
hills, the Benue and the plains of Muri, the peaks of the Murchison
Hills, Lake Chad, and the sands and swamps of Bornu, have become
familiar from the writings of both early and recent explorers.[1]
Equally striking, however, are the broad, flat-bottomed valleys of the
north-west, in which diminutive streams now represent the mighty rivers
of old; the rolling sandy plains of Hausaland[2] with their sluggish
rivers, their isolated granite domes and groups of rounded hills; and
the mysterious Bauchi plateau, the home of innumerable pagan tribes,
whose precipitous walls on the south and west long marked the limit
between the known and the unknown.
_Hydrographical Systems._ (Map. p. 4).
The Bauchi plateau, which rises to a height of 4,000 to 4,500 feet above
the sea, is the hydrographical centre of the Protectorate. From it the
rivers radiate north, south, east, and west; but while at first they
flow in such diverse directions, they become ultimately included within
one or other of the two great hydrographical systems, the Niger-Benue
system and the Chad or Inland system. All the rivers leaving the
plateau, with the exception of those flowing directly north, belong to
the Niger-Benue system. The “primary watershed,” or dividing line
between the two great hydrographical systems, runs from the
neighbourhood of Daura on the northern frontier of the Protectorate
south-westward between Katsina and Kano to the twelfth parallel. Thence
it runs south-eastward to the latitude of Zaria, and then southward to
the neighbourhood of Bukuru, on the summit of the plateau. From Bukuru
it strikes approximately north-eastward to Kerri Kerri, and thence
south-eastward to the Yola border in the neighbourhood of Mubi. Within
the Chad system the only important river is the Yo, of which the rivers
Hadeija, Katagum, Delimi, and Shidya form the headwaters. The Yedseram,
the only other large river of Bornu, forms for some distance the
boundary line between Nigeria and the northern territories of the
Kameruns. In the west the primary watershed of the Niger system
coincides approximately with the boundary of the Protectorate from the
eleventh parallel to the neighbourhood of Aiedi on the eighth parallel,
whence it runs eastward to Kabba, and thence southward through the
Egbira and Kukuruku hills into Southern Nigeria. South of the Benue, the
primary watershed runs through Southern Nigeria and the Kameruns
entirely beyond the southern limit of the Protectorate.
_The Niger._
The Niger enters the Protectorate at Ilo in the north-west, and flows
within the Protectorate for a distance of four hundred and fifty miles
to Idah on the Southern Nigerian frontier. Its breadth varies in places
from a few hundred yards in the dry season to several miles during the
rains. The annual variation in depth may reach at Lokoja as much as
thirty-five feet, and when in flood the river is navigable for small
ocean-going steamers as far as Baro, the terminus of the Baro-Kano
railway, and for light stern-wheelers as far as Bajibo, twenty miles
north of Jebba. Its largest tributaries within the Protectorate join the
Niger on the left, those on the right being comparatively short and
unimportant. On the left are the Kebbi, Malenda, Kontagora, Kaduna,
Bako, Gurara, and Benue; on the right the Wessa, Oli, Teshi, Awo, Oshin,
Oyi, Oro, Kampi, Mimi, and Meadowbank. Of these the Gurara is navigable
in flood for small stern-wheelers for a distance of thirty miles from
the Niger, the Kaduna as far as Wushishi at the foot of the rapids, and
the Kebbi as far as the confluence of the Jega river.
[Illustration: NORTHERN NIGERIA
Primary Watersheds and River Systems.
MAP No. 1.
London. Macmillan & Co., Ltd.
_Face p._ 4.]
The alternation of narrow gorge and open plain is a striking feature of
the Niger valley within the Protectorate. Where the channel is narrow
and bounded by steep cliffs on either side the seasonal variation in
level gives rise to comparatively little change in the aspect of the
river. The blackened rocks in the river bed and the sandy stretches on
either shore may be lost to view, but the flood is still confined within
its walls of rock. It is where a plain tract intervenes in the course of
the river that the contrast between the Niger in flood and the Niger at
low water becomes particularly striking. The sandy bars and shallows
which in the dry season present such obstacles to navigation, as well as
the grassy banks and islands of alluvium with their terraced slopes of
sand and clay, are buried during the rains under a flood, which may
spread for miles over the plain on either side of the river.
At Idah the Niger narrows and flows swiftly between low cliffs of white
sandstone which pass northward into stretches of wooded rising ground on
either bank. Ten miles above Idah a group of flat-topped hills approach
the right bank of the river, only to turn off abruptly inland in a line
of buttresses six to seven hundred feet in height. Farther on, the low,
flattened ridges on the left bank run out in a line of rounded hills:
and beyond, the river broadens and a broken plain stretches inland to
distant groups of lofty hills. Nearing Itobe Mount Purdy stands out, a
solitary cone, in advance of the level-crested plateau beyond. From
Itobe to Igbo the Niger flows through the most picturesque portion of
its lower course.[3] The hills rapidly close in, the channel becomes
narrow and rocky, lofty granite domes and rounded hills separated by
narrow gloomy valleys rise up on either bank, and on the left the level
crest of the plateau looms behind on the sky-line (Plate I, Fig. 1).
Below Lokoja the river opens out, the hills die down on either side, and
from the left bank a broken hummocky plain stretches inland to the base
of the Bassa hills, while at Lokoja itself flat-topped Patti (Plate I,
Fig. 2), with its projecting buttresses and the red roofs of the
cantonment at its base, stands sentinel over the confluence of the Niger
and the Benue (Plate II).
An extensive alluvial plain annually flooded during the rains stretches
away to the Benue from the left bank of the Niger for long miles above
Lokoja. The right bank is occupied more or less continuously by the worn
escarpment of the plateau of which Mount Patti forms the southernmost
extremity. Above Koton Karifi the hills reappear on the left bank, and
for more than twenty miles the Niger flows between the broken walls of
what has once been a magnificent river gorge. In places for considerable
distances the flat-topped hills still rise up with precipitous slopes on
either side in all their ancient grandeur. More frequently, however, the
escarpments are rounded off and much eroded by lateral valleys, while at
times they recede to a distance, and leave between themselves and the
river a more or less extensive swampy plain, with here and there a flat-
topped remnant of the once continuous plateau. Before Baro is reached,
however, the plateau has disappeared on the right bank, and on the left
is represented only by more or less isolated flat-topped fragments. The
bend of the Niger at Egga and Kacha marks the eastward limit of an
extensive alluvial flood plain, which includes the lower courses of the
Kampi and the Bako, and stretches westward on the north bank as far as
the Kaduna. On the south bank the pinnacle peaks of Egbom[4] tower high
above the river, while a flattened ridge extends westward as far as
Pategi. Beyond the Kaduna the Niger flows through a broad and shallow
valley with extensive swampy plains on either hand, and only at Shonga
on the right bank and at Rabba on the left does the river approach the
rising ground which elsewhere bounds the valley in the distance.
At Jebba the hills close in on either side, and the Niger issues by a
double channel from a picturesque gorge which extends northward as a
deeply cut and rocky valley as far as Bussa, a distance of seventy-five
miles. For eight hundred yards above Jebba the gorge is narrow and
bounded by vertical walls of quartzite. The Juju Rock[5] and the other
islands which interrupt the channel mount steeply from the river, the
rapid current pours over sunken rocks which rise abruptly from the river
bed, and mighty whirlpools bear witness to the depth of the water.
Beyond Jebba the quartzite gives place to granite, the vertical walls
become rounded, wooded slopes, the river broadens its rocky bed and
flows in a narrow valley between two belts of broken hilly ground which
lead up to the plains of Kontagora and Borgu, five hundred feet above
the level of the river. In spite of the obstructions in the channel the
river is navigable with caution for small stern-wheelers as far as
Bajibo. Above Bajibo, however, navigation becomes precarious and
dangerous even for native canoes. The current becomes more violent;
rocks, cascades, and whirlpools more numerous, and small rapids more and
more frequent, until above Leaba the Niger flows in a rocky gorge which
leads to the base of the Great Rapid of Wuru.[6] Here the river is
formed of two branches with a rocky island between. The fall of forty
feet between the summit and foot of the rapid is distributed over some
thirteen hundred yards of river, giving a slope of at least 1 in 100 and
a current of from fifteen to eighteen miles an hour. In the rains the
granite boulders are completely submerged under a seething flood, and
even in the dry season the water is thrown up by the projecting rocks in
sheets of foam, and the roar of the rapid is heard for long distances on
either side.
A stretch of two and a half miles of comparatively smooth water, broken
only by some small rapids and cascades, separates the Great Rapid of
Wuru from the rapid of Patassi, which is composed of two sets of
cascades, each twelve to fifteen feet in height and separated by a
straight reach of some two hundred and eighty yards. Twenty miles
farther on, the third important set of rapids is reached, the rapids of
Garafiri, whose cascades and whirlpools occupy a stretch of about three
miles between the villages of Garafiri and Malali. At Bussa, the scene
of Park’s disaster, the channel is still much obstructed by projecting
rocks and islands, and the small cascades and the rapid current still
render navigation both difficult and dangerous. The right bank of the
river is here formed of low, wooded rising ground, while on the left
ranges of low hills rise in series one behind the other. Soon, however,
the hills die down and the rocks disappear from the river bed, and at
Warra the river is broad and smooth with an extensive flood plain on
either side. From Warra to Ineku the Niger is formed of two branches, of
which the more westerly preserves the calm aspect of the river at Warra,
while the more easterly becomes again obstructed by rocks and rapids.
Between Ineku and Yelwa the river is bounded by low, rounded hills
covered with scanty forest, innumerable islands rise from the river bed
supporting an abundant vegetation, while several sets of lesser rapids
obstruct the channel. At Yelwa the banks become low and swampy, the
hills begin to recede from the river, and five miles farther on, near
the village of Sakassi, the last set of minor rapids occurs in the
channel. Beyond Sakassi the whole aspect of the river changes, the
channel becomes broad and sandy and obstructed by nothing more serious
than sand bars. On the north bank a broad, swampy flood plain, with low
rising ground in the distance, bounds the river as far as the mouth of
the Kebbi, and from the Kebbi to the swamps of Ilo an open sandy plain
stretches northward between the river and the base of the plateau. On
the south bank the gently undulating plain which bounds the river
stretches westward to the Dahomey border, broken only by some scattered
groups of flat-topped hills.
_The Benue._
The Benue enters the Protectorate to the east of Yola, and after a
course of nearly five hundred miles joins the Niger at Lokoja. Its
principal tributaries are on the right bank the Gongola, Kudu, Wase,
Simanka, Ankwe, Modu and Okwa; on the left bank the Faro, Ini,
Mainarawa, Tarabba, Donga and Katsena. The Benue is navigable when in
flood throughout its whole course for steamers of light draught. The
Katsena is navigable as far as Katsena Allah, the Gongola as far as
Nafada, and the Donga and Tarabba for considerable distances up stream.
In the matter of scenery the Benue presents a striking contrast to the
Niger. There is on the Benue no picturesque alternation of narrow gorge
and open plain; no rapids trouble its surface from Lokoja to the flat-
topped hills of Yola, and even in the dry season it is only at long
intervals that rocks are exposed in its sandy bed or in its steep banks
of alluvium. The precipitous front of Mt. Patti and the level crest of
the plateau on the right bank of the Niger are visible from the Benue
for twenty miles above Lokoja, across the great alluvial plain which
marks the confluence of the two mighty rivers. Above Mozum a range of
flat-topped hills with occasional peaks follows the right bank for some
distance, but soon turns inland and leaves a broken plain between the
river and the base of the hills. A similar range, also separated from
the river by a broken plain, runs parallel with the left bank a few
miles inland. The escarpments of these ranges on either side of the
river represent the walls of a broad flat-bottomed valley which is
comparable in origin with the steep-sided gorge of the Niger above
Lokoja. Here on the Benue, however, erosion has been more intense, and
the hills have been cut farther back on either hand.
Above Umaisha a tract of broken country stretches eastward on the north
bank and gives place in the neighbourhood of Loko to alluvial swamps in
the foreground, with undulating sandy plains beyond. On the left bank,
meanwhile, the hills approach the river at Amara and pass eastward into
a hummocky plain, which is bounded to the south by a distant range of
flat-topped hills. Above Loko the Doma Hills touch the river at Udeni on
the right bank, but turn off abruptly inland with their low, buttressed
slopes overlooking an extensive swampy plain which stretches eastward as
far as Akwaneja. Beyond Akwaneja the right bank assumes a similar aspect
to that of the left. The river is bounded by low, well-wooded banks,
with here and there a projecting mass of sandstone, while a hummocky
plain stretches inland on either side to distant rising ground. The
volcanic tract above Abinsi introduces an agreeable change into the
monotony of the scenery. The worn and weathered cones and banks of lava
stand out picturesquely from the wooded plains, and on the river-side
the black basalt and the yellow sand offer a pleasing contrast to the
eye. Soon, however, the low banks resume their familiar aspect and a
featureless plain spreads out on either hand. Nearing Ibi the right bank
becomes low and swampy, and the great plain of Muri opens out beyond.
From Ibi to Lau the channel is broad and sandy, and the river winds
about amongst everchanging sand-bars and banks of alluvium. In the rains
broad stretches are flooded on either side, and for long distances on
the right bank the plain beyond becomes an almost impassable swamp,
while on the left long tongues of marshland run up the tributary
valleys. Far to the north the peaks of the Murchison Hills[7] tower high
above the plain, while to the south the rock of Bantaji guards the
swamps of the Donga.
PLATE I
[Illustration: ON THE NIGER ABOVE IGBO.]
[Illustration: LOKOJA AND MOUNT PATTI.]
Farther east, and especially between Numan and Yola, the river plain is
traversed by a large number of anastomosing channels, which in many
cases are only connected with the main stream during the rains, and in
the dry season are cut off by sand-bars into strings of shallow pools
and marshes. Alluvial mud covers the rocks for some miles inland, and
while in the rains travel on foot is impossible and the villages are
isolated one from another, in the dry season the ground shrinks and is
broken everywhere by wide cracks. This alluvial plain is perfectly
level, so that the small volcanic mounds, dotted here and there, which
in a more varied country would be overlooked, form conspicuous
landmarks. The most striking of these hillocks is Jeme Hill, below
Numan, which stands on the river bank and can be seen for twenty miles
around. (A. L.)
The Benue plain, which is so extensive in Muri province, contracts near
Lau, and thence eastward it is limited on both sides by plateau areas
which rise suddenly and steeply at distances of fifteen miles from the
river. These masses of hills with their varying outlines introduce a
pleasing change into the hitherto monotonous river journey, and contrast
sharply with the river plain. Here the plain of the Benue is like a
broad and shallow trench, bounded by sharply rising walls, whose height
is small compared with the distance between. At the same time the height
is considerable in itself, for the rise to the plateau is well over a
thousand feet. (A. L.)
These hills running eastward parallel to the river are breached by the
Gongola plain, about ten miles wide, entering from the north, and by the
plain of the Ma-Ini and Maio Belwa entering from the south. Farther on
the hills come in again. To the north they are rather scattered and
detached, with long tabular outlines, or, as in the Bagele Hills, with
terraced sides and abrupt scarps. On the other side, though flat-topped
hills do occur, the outlines are usually more varied, while south of
Yola rises the typical plateau of the Vere Hills—a solid mass fronting
boldly outwards upon the surrounding plains with continuous rocky faces
indented by a few deeply-cut and narrow valleys. Meanwhile the plain of
the Benue with its flat and marshy character continues eastward beyond
Yola and the Faro river into the German Kameruns. (A. L.)
Along the whole course of the Benue from Lokoja to Yola exposures of the
underlying rocks are very infrequent, and this remark applies equally to
the lower courses of the tributaries. The main trunks of the Benue
system have long passed the stage at which they effected any appreciable
erosion, and now serve only as the channels along which detrital
material brought down by the head-waters is transported to the Niger.
The finer portion of the material is carried in suspension, and is
responsible for the covering of alluvial mud found over those parts of
the river plain which are inundated during the annual rise. The coarser
portion is rolled along the bottom and gives rise to the sandbanks.
These are covered in flood, but for the other part of the year they are
a constant feature of the river scenery. The stream, much lessened in
volume, swings first to one side and then to the other of the wide river
bed, with the broad sandbanks occupying the bends. (A. L.)
The sand is rather coarse, principally of clean grains of quartz and
felspar, but at times with pebbles of vein quartz or occasionally of
polished limonite. Typically, a spread of sand, many acres in extent and
with its level surface only a few feet above the water, ends on the
down-stream side in a slope which plunges into deep water at perhaps
40°. While the river is falling, the formation of these sandbanks can be
well studied. The water, covering the sandbank by only a few inches, is
seen to sweep grains of sand or occasional pebbles along over the level
surface till they reach the end of the bank and roll down into deep
water, thus helping to form the next lamina. In this way the sandbank is
built up of successive laminæ inclined down stream at a steep angle to
the horizontal, and wherever a bank is cut into by a change in the
direction of the current the inclined lamination is beautifully
displayed. The lamination is of course only a particular instance of the
“current bedding” produced whenever detritus in process of deposition is
subjected to currents of air or water, but it is important to understand
that the oblique lamination of the sandbanks is brought about by the
river currents, and not by the wind as has been supposed. Any slight
rearrangement of the surface layers by wind is obliterated by the next
rise of the river. (A. L.)
_The Niger Provinces.—Kabba, Ilorin, Borgu, Kontagora, Nupe._
The orographical structure of Kabba and Ilorin is somewhat complex. The
primary watershed of the Niger basin which runs from Kabba to Aiedi and
thence westward a few miles south of the Ilorin frontier, is not defined
by any range of hills or mountains, but by the crest line of a lofty
plain which, like a low, extended arch, slopes gently northward towards
the Niger and southward towards the sea. In central Kabba the high plain
assumes, to some extent, the character of a tableland, which is bounded
to the north-east by the Lukke hills and the broken ground beyond the
Mimi valley. To the east and south-east the tableland is abruptly
limited by the worn escarpments of the Shokko Shokko, Agwede and Egbira
hills, at whose base, 500 feet below, are spread out the broad, well-
watered and well-wooded plains which stretch away eastward to the Niger,
and of which passing glimpses are caught from the river below Itobe. To
the south these undulating plains slope gently upward and inward from
the Niger and lose themselves in the narrow valleys of the Kukuruku
Hills.
Although such in brief is the orographical character of the major
portion of Kabba and Ilorin, the actual conditions of the surface and
the peculiar character of the scenery to some extent obscure the issue.
In central Kabba the undulating surface of the tableland is in places
densely wooded, in places covered with thin bush, in places open,
grassy, and park-like with cultivation near the towns and villages,
while above the plain at frequent intervals rise isolated rounded hills
or groups of hills, or even short rocky ranges, which form secondary
watersheds between the minor streams. Similarly, on the lower plains
adjoining the Niger, the attention is arrested by the dome-shaped island
mountains and picturesque clusters of rounded hills which rise abruptly
into view. The full significance of this peculiar type of scenery can
only be grasped when gazing from the summit of one of the isolated hills
themselves, or from some favourable spot on the crest of the escarpment
which separates the higher from the lower plains. Then all the minor
irregularities disappear, and the level, wooded surface of the plain can
be seen stretching up to and around and between the bases of the hills
which rise like rocky islands from a verdant sea. The hills may be
covered to the summit with angular _débris_ and scanty forest, or the
lower slopes may be littered with exfoliation fragments, amongst which a
few trees find a precarious footing, while the summit may be smooth and
bare, with a few large boulders perched picturesquely in apparently
impossible positions. The contours of the bare and treeless summits are
frequently particularly graceful with beautiful domes and cupolas rising
from gently-rounded slopes of granite or gneiss. In many cases a
precipitous path leads to the village which caps the summit, while for
long acres round the base the plain is cleared and cultivated. (Plate
XVII.)[8]
The northern part of Kabba is more rugged, the population is more scanty
and forest more abundant. The rocky valley of the Mimi is bounded to the
north by the broken, hilly ground between Jakura and Akpara, which
passes to the east and north under the flat-topped sandstone hills which
fringe the Niger. The Jakpara Hills with their conical peaks upon
rounded bases are landmarks for miles around. The white quartzite hills
in the neighbourhood of Lukke alternate with belts of soft schists which
support a luxuriant forest growth. Farther west by Moppa, Sanlu and
Takete detached groups of granite hills rise upon an undulating plain.
The thicker vegetation, however, obstructs the view, and it is only when
the landscape is surveyed from the summit of one of the higher hills
that the structure is seen to be very similar to that of southern Kabba.
To the west, Ogga and Eri are set within a cluster of rocky hills, while
to the north there is a comparatively rapid fall to the plains of the
Kampi. Between the Kampi and the Niger a steep-sided range of sandstone
hills capped by the pinnacle peaks of Egbom (p. 7) runs out westward in
a succession of rounded ridges two hundred feet above the level of the
river, and not until near Share is the river belt of sandstones again
bounded by a low escarpment. The Shappa and Orissa Hills form the only
prominent range in central Ilorin. The Shappa Hills are of granite, and
many of the peaks are gracefully rounded and most picturesque, while the
quartzites and gneisses of the Orissa hills give more rugged and
irregular contours. West of the Orissa hills lies the great plain of
Ilorin, thickly populated and well cultivated, in broad undulations
trending generally north and south, with scattered inselberge and many
kopjes of granite boulders, but with no conspicuous ranges or groups of
hills. The Jebba hills, which extend southward for some distance towards
Ilorin, pass westward into an extensive tract of hilly country, high
lying, little known and largely uninhabited, which forms a natural
boundary between Ilorin and Borgu.
The primary watershed of the Niger basin follows the frontier of the
Protectorate more or less closely from the eighth parallel to the south
of Ilorin as far as Okuta in the west of Borgu, whence it runs northward
to the latitude of Nikki before turning off westward into Dahomey. With
the watershed the high plains, along whose crest it runs, also swing
round to the west of Borgu and fall off gently towards the Niger on the
right, while along the river itself from Bussa to Jebba a narrow belt of
broken country marks the transition from the high plains of Borgu to the
gorge-like valley of the Niger.
Southern Borgu is one of the least inviting districts in the
Protectorate. The rocks are concealed almost everywhere by recent
alluvium or by surface ironstone,[9] which in places forms extensive
platforms entirely bare of vegetation. Where rocks do emerge from the
superficial accumulations they seldom form hills. The granite hills
around Kiama are an exception to this rule, and along the western
frontier a number of granite domes rise from two to three hundred feet
high. These domes, however, are separated by wide stretches of country
over which all geological processes seem to have come to a standstill.
The drainage system is very poorly defined, and for the most part the
water is carried off, not by stream courses with sand and boulders, but
along shallow, soil-covered depressions in the plain. Such streams as
there are dry up soon after the end of the rains, and the natives then
resort largely to wells dug in the surface soil. The crests of the
gentle undulations follow one another on the sky-line in endless
succession, and the journey becomes monotonous in the extreme. The
northern part of the province is diversified by a number of sandstone
hills, and some swift, clear streams, fed from springs at the base of
the hills, afford a welcome change to the jaded traveller. (A. L.)
In the provinces which lie to the east of the Niger the intimate
relation which exists between the character of the scenery and the
nature of the rocks becomes increasingly evident. In Kabba, Ilorin, and
Borgu, where crystalline rocks of a granitic or gneissic character cover
by far the larger part of the surface, the prevailing and most
characteristic type of scenery is that of rolling sandy plains with
isolated hills or groups of hills rising abruptly above the general
level. On the other hand, where sedimentary rocks, such as sandstones
and ironstones, cover the surface, as in the river belt of sandstones in
Kabba and Ilorin, the characteristic type of scenery is that of steep-
sided and flat-topped ranges and plateaux, with detached tabular and
conical hills rising from the lower plains. Over the greater part of
Kontagora province, to the north of the parallel of Kontagora itself,
granites and gneisses form the surface rock. In the west, near N’gashki,
a group of granite hills rises abruptly from the plain which stretches
away to the east, with its surface diversified in typical fashion by
occasional inselberge. A belt of slaty rocks much pierced by quartz
veins runs along the left bank of the Niger from N’gashki to Yelwa, and
gives rise to a stretch of broken country adjoining the river. The
granites and quartzites in the lower valley of the Malenda river also
give rise to much rough and stony country, which culminates in the
quartzite hills of Maibirro. Beyond Jindani and Yelwa the plain
reappears in a more typical character, and stretches northward as a
gently undulating surface covered with deep, sandy drift, from which
emerge at long intervals low, rounded, or rocky hummocks of granite or
gneiss.
PLATE II
[Illustration: THE CONFLUENCE OF THE NIGER AND THE BENUE.]
[Illustration: It is in the east of the province, however, between
Banaga and Kotonkoro, that the landscape assumes the typical aspect of
the high plains of Hausaland. In front, behind, and for long miles on
either hand, the open, sandy plain stretches away to the horizon, with
here and there a low turtleback or heap of granite boulders, and at long
intervals a loftier dome or a group of rounded granite hills. The rivers
flow in almost imperceptible valleys in broad, sandy channels, or over
smooth and bare surfaces of rock, level with the plain, while the low
watersheds between the rivers are crossed almost unconsciously by the
traveller.
The country around Kotonkoro and to the south-west is extremely
picturesque. Numerous domes of bare rock rise from a grassy park-like
country. The plain around one of these domes passes imperceptibly into a
gentle slope of sandy wash, which leads the eye up to the spring of the
dome. As the path winds along, first one and then another of these domes
engages the attention. On approaching Mahorro two of the highest hills
have flattened summits and are found to be capped by about twenty feet
of stratified ironstone. To the north-east of Kontagora these outliers
are more numerous, though seldom of a sufficient size to mark on the
map. The country is in consequence very rough and broken and the track
becomes difficult and stony. The poor agricultural prospects, however,
are compensated for by good iron ore, and the crude native furnaces soon
come to be a familiar sight. When these outliers are finally left behind
at Libo, a belt of very rough broken country has to be crossed before
descending to the Kara river. (A. L.)
The town of Kontagora is set in an open undulating sandy plain, deeply
covered with surface drift, which stretches eastward to Moriga and the
Kara river, with its surface diversified by a few isolated sandstone
hills near Kontagora and a group of granite hills at Beri. To the south
of Kontagora begins the sedimentary series which stretches southward
into Nupe province and westward to within a few miles of the Niger. The
change in the nature of the surface rock is accompanied by corresponding
changes in the character of the scenery. Here at first are the same
rolling sandy plains, if possible more deeply covered with drift than
before; but here are no turtlebacks or lofty domes of granite forming
conspicuous features in the landscape, no rivers flowing over smooth
surfaces of rock in valleys so shallow that they are almost
indistinguishable from the plain. In place of these are low, flat-topped
sandstone hills rising singly or in groups above the general level, and
deep and narrow canyon-like valleys cut down, it may be, fifty or a
hundred feet below the surface of the plain. A typical group of hills
with their level summits of hard ferruginous grit and their slopes
covered with rounded boulders of the same occurs at Madara, a few miles
south of Kontagora, while at Kagara, Kaboji, and Sonko the streams run
in typical canyon valleys, whose presence is unsuspected upon the plain
until the chasm opens abruptly at one’s feet. The larger rivers flow in
broad, trench-like valleys, with their steep and wooded slopes covered
with rounded pebbles and boulders of ironstone and grit. To the west the
plains pass into the belt of hilly ground which leads to the Niger
valley, and which in its eastern portion shows the characteristic
tabular outlines of the sedimentary series, and in the west, adjoining
the river, the rugged irregular contours of broken crystalline hills.
The province of Nupe is somewhat unequally divided into two parts by the
Kaduna river. With the exception of the quartzite and granite hills of
Jebba and Kailema and the crystalline rocks of the eastern corner of the
province between Badegi and the Gurara river, the entire surface is
covered by sandstones, which are continuous with the sedimentary series
of southern Kontagora. West of the Kaduna, however, the high plains
become much dissected and broken up into extended tabular ridges and
irregular plateau-like masses, with the tracks leading over a succession
of low, well-wooded hills and shallow, flat-bottomed valleys bounded by
rough and stony slopes. On either side of the Kaduna rise isolated
tabular hills and short ranges separated by long stretches of open
plain, while to the east of Bida there open out the great rolling sandy
plains of Nupe, which extend from the Bako river to Badegi and southward
to the bend of the Niger. Beyond Kacha the character of the landscape
again changes: scattered hills and short ranges diversify the surface
and coalesce southward into the extended flat-topped ranges and
plateaux, whose wooded slopes dip steeply down to the narrow ledge of
crystalline rock which fringes the Niger. In the north-eastern angle of
the province beyond Badegi the sandstones give place imperceptibly to
granites and gneiss. The sandy plains of Nupe are continued eastward,
but their drift-covered surface presents now the characteristic features
of a crystalline floor. Knobs and hummocks and low ridges of gneiss
project here and there above the general level, while lofty groups of
rounded granite hills, like those of Gaung, rise abruptly and
picturesquely from the plain.
The sandstone plateaux which bound the Niger to the north of the Gurara
river are continued southward as far as Koton Karifi, and pass eastward
into Nassarawa as a dissected system of flat-topped and conical hills.
To the south of the confluence of the Niger and the Benue, the scenery
on the left bank of the Niger in Bassa province, as already described
(p. 6) is that of a hummocky plain with groups of rounded hills in the
foreground, backed and capped by lofty plateaux and conical hills. Such
a type of scenery is readily explicable as that of a dissected
sedimentary series resting upon an irregular crystalline floor of
granite and gneiss.
_The Benue Provinces. Bassa, Nassarawa, Muri, and Yola._
With the exception of the narrow strip of crystalline rocks exposed
along the Niger, the province of Bassa, so far as known, is entirely
covered by the sedimentary series whose western and northern escarpments
are visible respectively from the Niger and the Benue. These
escarpments, however, which from a distance appear continuous, are found
on nearer view to be much incised by river valleys which have been cut
back for long distances into the high ground behind. A system of lofty,
flat-topped and conical hills, extended ranges and plateau-like masses,
separated by narrow, steep-sided valleys, has thus been dissected in the
north and west out of the once continuous tableland. In the interior the
relief lessens, and the surface of the tableland becomes broken up into
a succession of tabular ranges and rounded ridges, separated by shallow
valleys well cleared for cultivation. The hills are usually thickly
wooded and the paths frequently rough and stony and covered with pebbles
and broken fragments of ironstone. In the south the Akpoto country
becomes in places particularly hilly and difficult, while the little
known Munchi country in the east is said to open out into undulating
park-like plains beyond the belt of forest which fringes the river.
For purposes of description the province of Nassarawa may be
conveniently divided into three portions, the river belt of sandstones,
the central crystalline plains and hills, and the northern tableland.
The Gurara river forms the greater part of the western and northern
boundary and drains all but the eastern portion of the elevated plains
in the north. The river belt of sandstones between the Gurara and the
Okwa in the west presents the characteristic and familiar scenery of a
dissected sandstone tableland. Beyond the Okwa river the flat-topped
hills and ranges die down into undulating sandy plains which stretch
eastward as far as the Modu river, while the detached group of hills,
which strikes inland from Udeni, is the last prominent tabular range on
the lower Benue. Farther east, the low-lying plains stretch into the
unexplored land of the Munchis, while to the north the trade route from
Loko to Ibi leads over well wooded undulating plains deeply covered with
sandy drift. The solid rock is frequently exposed in the beds of the
larger rivers and streams which have cut their channels through the
superficial accumulations; and here and there, as at Doma and Lafia,
groups of low rounded sandstone hills and projecting hummocks of grit
diversify the surface of the plain.
Central Nassarawa is, in the west, particularly broken and rugged.
Around Gwombe and Gwagwada and as far east as Buga a mass of low rounded
hills has been carved out of a series of soft micaceous schists. The
rocks are much decomposed on the surface into red gritty earth which
supports an abundant vegetation and in which the rivers and streams have
cut deep and narrow channels. To the north these rounded hills pass into
a tract of exceedingly difficult and broken country where precipitous
hills of granite and gneiss, separated by narrow rocky valleys, rise to
a height of two thousand feet above the sea. This mountainous tract, of
which the Karshi hills are the northern prolongation, forms the
secondary watershed between the river systems of the Gurara and the
Okwa. Beyond the Karshi hills a lofty and rapidly undulating plain, in
places rough and stony, and much diversified by inselberge (Plate IV,
Fig. 1) and short ranges of granite hills, stretches north-westward
towards Abuja. The Abuja Rock, a typical granite mount, streaked and
channelled by the summer rains, is a far-famed local landmark and an
object of superstitious veneration to the inhabitants of the surrounding
country. (Plate III, Figs. 1 and 2.)
Eastward from Buga to Nassarawa extends a broken plain with hummocks of
gneiss and detached groups of granite hills. At Kurudu, the Okwa river
flows through a narrow picturesque gorge between two rounded granite
hills, with the bare rock in the river bed honeycombed with potholes.
Nassarawa itself is set in the midst of gently undulating park-like
plains, well wooded and well cultivated, which extend northward as far
as Keffi and are continuous southward with the sandy plains of the river
belt. To the east they are limited by the rocky mass of the Anagoda
hills and the broken hilly ground between Keffi and the Modu river. To
the north of Keffi there opens out the great central plain of Nassarawa
which extends from the neighbourhood of Abuja in the west to the Mada
country in the east, and is limited northward by the worn escarpment of
the northern tableland. Turtlebacks and kopjes of granite and broken
hummocks of gneiss rise at intervals from the undulating surface of the
plain, while the minor irregularities are obscured, as usual, by deep
sandy drift. The larger rivers flow in broad sandy beds with long
stretches of swampland on either hand, or, where the drift is thinner,
in narrow rocky channels with belts of broken plain on either side from
which the surface drift has been in large part removed.
PLATE III
[Illustration: ABUJA ROCK.]
[Illustration: ABUJA ROCK FROM THE WALLS OF ABUJA.]
Viewed from the central plain, the margin of the northern tableland is
in places particularly picturesque. A well-marked, though much worn and
rounded escarpment (Plate IV, Fig. 2), extends continuously from the
neighbourhood of Kari in the west by way of Kukwi, Tatara, and Jaginde,
to Darroro and Assab in the east, and the skyline is variously
ornamented by domes, cupolas, conical peaks and perched blocks, with
here and there, as beyond Darroro, a jagged wall of granite rising
perpendicularly from the plain. The escarpment is steeper in the east
than in the west, and beyond Kari it is lost in the broken hilly ground
around Abuja, which falls in a succession of rocky steps to the plains
of the Gurara. The tableland itself slopes gently towards the Gurara,
and in the west, in the picturesque Gwari country, the numerous domes
and turtlebacks of granite afford ideal sites for pagan villages.
Parallel with the escarpment runs a narrow belt of broken country which
represents the worn edge of the tableland, while to the north the
undulating park-like plains, diversified by inselberge and groups of
rounded hills, wrapped closely round with sandy drift, recall in every
detail of scenery the central plain of Nassarawa below. A belt of broken
rising ground, stretching northward from Jaginde, separates the Gurara
system from the Kogin Kogom which drains the grassy plains of Morrua and
issues behind Jaginde from a narrow rocky valley cut backward for a
considerable distance into the plateau. The flat-topped granite massif
of the Kagoro hills, whose precipitous wall forms the continuation of
the escarpment from Darroro to Assab, projects also on the north above
the plateau and overlooks the lofty undulating plains of Morrua and Akul
which stretch away northward towards the Kaduna. Far away to the south
of Darroro, the peaks of the Mada hills can be seen across a broken
wooded plain: but this eastern portion of the province is as yet unknown
and unexplored.
The great plain, which forms the major part of Muri province, extends
from the base of the Murchison hills on the north to the frontier of the
Protectorate on the south, and from the Ankwe river in the west to the
Wurkum and Shebshi hills in the east. With the exception of the narrow
margin of crystalline rock in the north-west which runs parallel with
the Murchison hills, and the broader belt in the south between Takum and
Bakundi, the plain possesses throughout a floor of sedimentary rock. The
flat-topped hills, which are such a conspicuous feature of the scenery
of the lower Benue and the Niger, are here, however, entirely wanting.
The surface of the plain slopes gently towards the Benue from either
side, and into it the tributary rivers have cut a succession of shallow
swampy valleys separated by tracts of gentle rising ground, which run
approximately at right angles to the Benue. The undulating plain thus
produced is deeply covered with surface drift and relieved only by an
occasional hummock of sandstone or grit. The thin forest, which usually
covers the rising ground, gives place in the neighbourhood of the rivers
to extensive stretches of open grass land, which, in the rains, become
almost impassable swamps.
West of the Ankwe river the surface of the plain is more frequently
broken by ridges of rock, and around Awe and on either side of the Benue
to the south a number of worn volcanic cones are scattered over the
plain. (Plate V, Fig. 1.) Similar volcanic hills project above the
surface on the northern margin of the plain between Yelua and Wase. The
Wase Rock[10] itself, a pillar of trachyte, is a landmark for miles
around. (Plate V, Fig. 2.) At Namu, also, in the north-west of the
province, and at Bantaji on the Donga to the south of the Benue,
solitary hills of similar origin form striking features in the
landscape. Turtlebacks and kopjes of granite boulders are found only on
the margins of the plain where the floor is crystalline. In the north-
west the narrow belt of hummocky crystalline ground, with its inselberge
and groups of granite hills, is limited by the domes and pinnacles of
the little known Murchison hills,[11] while in the south the undulating
plains which stretch along the frontier of the Protectorate from the
Katsena river to the Tarabba present all the characteristic features of
a crystalline floor. In the north-east of the province, between Bashar
and Jeb-jeb, the plains stretch northward up the Kudu valley but are
limited to the east by the Ligri, Wurkum, and Jenoe hills, whose steep
and rocky sandstone slopes become in places quite rugged and
picturesque. The Kwana and Mumuye hills, which bound the plain to the
south of the Benue, are largely granitic and present the usual rounded
contours, while the foothills of the Shebshi range are of quartzite and
gneiss and give rise to more rugged and irregular outlines.
The Mumuye and Shebshi hills are portions of an extensive tract of hilly
country which stretches into German territory and which occupies the
southern part of Yola province.[12] The western boundary of this tract
runs almost northward, past Jalingu and Kwana, as if to approach the
Benue at Lau, but instead turns sharply at right angles. Running
eastward from near Kwana there is a practically continuous wall of rock,
and at Bamga a steep and almost precipitous climb brings the traveller
from Lau to Yola on to the rim of the plateau area. From this position
he looks out over the Benue plain several hundred feet below. The river
is far away to the north, while beyond that again, just discernible on a
clear day, is the further wall of hills stretching continuously from the
Wurkum country to the Gongola. Turning south, he sees the tumbled
Shebshi hills as a faint silhouette in the distance, while in the
foreground, slightly below him, stretch sandy uplands with a gentle
eastward slope. The track drops down upon the uplands and then proceeds
just within the rim of the plateau towards Yola. For the first day this
rim is made up of a chain of rounded hills. Then a number of sandstone
outliers arrests the attention. (Plate VI, Fig 1.) The sandstone is
massive and breaks down along vertical faces. The fallen blocks, in
assuming their position of rest, smooth off the irregularities of the
granite base, and from the truncated cones thus produced, the cliff-
sided outliers rise and dominate the landscape, like great fortresses.
From this point the plateau descends gently to the plain of the Maio
Belwa and Ma-ini rivers. (A. L.)
Opposite Lau the hilly ground to the north has similar outlines to those
of the crystalline plateau to the south. Farther east, behind Wuduku,
its appearance changes and the hills are composed of sandstone. Here the
ridge seems to be a bold escarpment limiting the unknown Yam-yam country
in precipitous cliffs, but with a dip slope to the south which plunges
down below the marshy levels of the Benue. Further eastward again there
is another change and the outlines of the hills become regular and flat.
Where the plain of the Gongola enters the Benue valley, they turn at
right angles and run northward parallel to the river. At the angle which
separates the two plains the mass is seen from a distance to be made up
of horizontal beds, with seven or eight terraces on its sides. These
hills, which run up to the west of Kombo, are still, however, unentered
and unexplored. (A. L.)
The plain of the lower Gongola is a repetition of the Benue plain on a
somewhat smaller scale. The floor of the trench is about ten miles wide
and the height of the walls perhaps a thousand feet. On travelling up
the Gongola, Kwaba hill is conspicuous two or three days before it is
actually reached. It is a massive hill of granite with numerous
satellites, of which some are of granite while others are outliers of
horizontal sandstones, bounded by vertical cliffs. The successive beds
are exposed in their sides like string-courses of masonry, the Gongola
outliers differing in this respect from those of southern Yola, which
have been carved out of unbedded sandstones. (A. L.)
The plateau of the Vere hills has been already mentioned (p. 14). It is
completely separated from the Karin mountains, Alantika mountains, and
other hilly ground to the south by broad and level plains. The essential
feature of the scenery is the contrast between the plain and the plateau
masses. They rise up from one to two thousand feet higher than the
plain, with no transitional foothills or slopes. The base is concealed
by sandy wash, and at intervals streams, issuing from the plateau by
narrow ravines, trench down through the compacted wash to form steep-
sided nullahs. (A. L.)
Opposite to the Vere hills and across the Benue stand the Bagele hills.
A little further north is the Hossere Furo. Both groups are of
sandstone, rising up from the smooth grassy plain. The rise, however, is
not immediate, as it is in the Vere hills, but through basal slopes and
foothills toward the higher summits. North-eastern Yola consists of a
high-level plain, elevated considerably above the plain of the Benue,
but passing into it more gradually than do the plateaux to the south.
There is, however, one step of about 200 feet running eastward from Song
to the frontier, while the belt of country twenty miles broad to the
north of it forms rather a curious contrast to the remainder of north-
eastern Yola. Possibly there has been a slight local uplift. Granite is
seen over almost the whole surface breaking down into coarse sand and
giving rise to a hummocky country difficult to travel. The variations in
level are only small, and taken as a whole it is still a plain, but the
breaking down of the granite is going on actively over the whole
surface. Parallel to this country and almost in alignment with it, is an
interesting string of craters and flows of basalt. (Plate VI, Fig. 2,
VII, Figs. 1, 2.) The eastern extremity of this line appears to be at
Song, but westward it extends across the Mboi hills into the Yungeru
country, to what distance is not yet known. The remainder of north-
eastern Yola, with its rocky islets set in extensive thinly wooded
plains, is similar in character to that of so many other parts of the
Protectorate. Some of the inselberge, especially in the Kilba hills
(Plate VIII, Fig. 1.), afford excellent examples of exfoliation. (A. L.)
_The Central Provinces.—Zaria and Bauchi._
The province of Zaria lies almost entirely within the drainage basin of
the Kaduna river, only a narrow belt of country in the south and south-
west being drained by the rivers Gurara and Bako. With the exception of
the uppermost springs of the Kaduna and the lower navigable portion of
its valley below Wushishi, the whole course of the river is included
within the province. At Wushishi the river narrows and its channel
becomes much obstructed by rocks and rapids, as it winds through the
belt of hills which separate the rocky plains of western Zaria from the
lower plains of Nupe. At Zungeru the Kaduna flows in the dry season in a
narrow picturesque gorge between white walls of quartzite, which in the
rains are buried under a rushing foaming torrent. (Plate VIII, Fig. 2.)
From the bend of the river above Girku in the east of the province, the
Kaduna flows south-westward over stretches of drift-covered plain and
through scattered groups of hills with its channel marked by frequent
rocks and rapids, while beyond Girku the river meanders peacefully over
the lofty plains which stretch eastward to the boundary of the province.
The larger tributaries of the Kaduna on the north bank, the Kara,
Koriga, Tubo, and Shika, take their rise upon the high plains of
Hausaland, along whose crest runs the primary watershed between the
systems of the Niger and Lake Chad, and, like the Kaduna itself, they
flow in their middle and lower courses over broken plains and between
groups of hills which separate the minor streams. The Leri river in the
east rises on the high plains of the Bauchi border, while the Dunia and
Serakin Pawa, the principal tributaries on the left bank, as well as the
headwaters of the Gurara, take their rise amidst the scattered hills
upon the lofty plains of the south-east. The Bako river rises in the
hilly ground around Fuka and, with the Gurara, drains the extreme
southern portion of the province.
The hills in Zaria province are of two types; (1) ranges or belts of low
rounded and somewhat broken hills, composed largely of the more
resistant schists, or of a mixture of granite and schist; (2) kopjes,
inselberge and small detached groups of rounded granite hills, with here
and there an extensive elongated mass of granite with a more or less
flattened tabular summit and steep though worn and rounded slopes rising
abruptly from the plains which encircle its base. To the first type
belong the tract of hilly country in the west of the province which
stretches from Mikonkeli to the south of the Kaduna as far as Kagara to
the north, the belt of hills between Gwari and Koriga in the north of
the province, the broken stony country around Fuka in the south, and the
line of hills in the centre of the province from Dorka to Kaserimi. To
the second type belong the solitary turtlebacks and detached masses of
granite hills which so abundantly diversify the plains, while the
Kudaru, Ruruma, and Kerko hills are somewhat worn examples of the steep-
sided granite massifs, whose flattened though hummocky summits form the
retreat of numerous pagan tribes.
Over the greater part of the province the configuration of the surface
presents a very close resemblance to the characteristic scenery of the
plains of Kabba (p. 17). Between and around the island mountains and
groups of hills and tracts of hilly country, spread undulating thinly-
wooded drift-covered plains. The towns and villages are set
picturesquely on the slopes and summits of the hills or in patches of
thick forest in the midst of the plain. For long distances round the
bases of the hills the plains are cleared and cultivated, and from the
summit of any of the isolated mounts the peculiar character of the
landscape impresses itself, as before, upon the observer. Here and there
the solitary hills raise their rounded crests in lonely grandeur, while
around and between them the rivers pick their sluggish course over the
monotonous plain. The lofty drift-covered levels of the south-east are
largely uninhabited and cultivated only by the pagans who daily descend
from their rocky strongholds in the Ruruma Hills or on the margin of the
Bauchi plateau. Only in the north-east between Girku, Leri, and Zaria do
the plains assume the typical aspect of Hausaland (p. 21). The gently
undulating surface is deeply buried in sandy drift, and in places
floored with surface ironstone: extensive stretches of the grassy plains
become swampland in the rains: the landscape is diversified only at long
intervals by occasional turtlebacks and groups of granite hills, while
well-walled towns and villages are set here and there upon the open
plains or built round the bases of the solitary hills themselves, which
serve as watch-towers in times of danger.
The major part of the province of Zaria may be conceived as a shallow,
elongated basin, draining westward, and shut in on the north and north-
east by the high plains of Hausaland and on the south-east by the Amo,
Piti, and Chawai hills, the lofty plains of Katab, and the tableland of
Nassarawa. The greater part of Bauchi province, on the other hand, may
be looked upon as an undulating plain sloping gently towards the north-
east. The south-western portion of the province is occupied by the great
plateau of Bauchi, which is limited on the north and south by well-
defined walls of rock. (Map p. 40). The plateau, however, is not a true
tableland in the sense of an elevated plain marked off on all sides by
precipitous walls from the lower plains around. Like the tablelands of
Kabba, Nassarawa, and Southern Yola, which are at most inclined plains
bounded by escarpments on one side only, the Bauchi plateau from its
summit at Bukuru slopes gently eastward and merges gradually into the
plains of the Gongola, while on the west between the northern and
southern escarpments it is continuous for a short distance between Kwoll
and Assab with the highest portion of the tableland of Nassarawa. The
intimate relation which exists between the Bauchi plateau and the
tableland of Nassarawa is further demonstrated by the continuation of
the escarpment of the tableland beyond Assab to form the southern wall
of the plateau. From Assab the escarpment, here 1,500 to 2,000 feet in
height, runs south-eastward to the neighbourhood of the ninth parallel
before swinging round to the north-east and losing itself amongst the
rocks of Angass, where the single escarpment appears to be replaced by a
succession of rocky steps leading down to the tract of broken country
between Angass and Kanna, which is drained by the headwaters of the Wase
river.
The northern margin of the plateau is more irregular than the southern
and marked by projecting spurs which have now assumed the character of
mountain ranges. In the west the escarpment begins in the neighbourhood
of Kwoll and Miango and stretches westward as a somewhat worn and
rounded cliff, 1,000 feet in height, separating the lofty plains of
Rukuba from the lower plains of Zaria. Beyond Chawai and Piti the
escarpment is continued as the western slope of the Amo, Jengre, and
Gura hills, which run out upon the broken plains to the north, while the
eastern slope of the hills again assumes the character of an escarpment
and bounds the valley of the Delimi as far as the gorge of the river
below Naraguta. To the east of the Delimi, however, the single
escarpment is replaced by at least two steps which interpose the broken
plains of Toro and the summits of the Kwandokaya hills between the
plateau and the northern plains, while to the south-east of Polchi the
escarpments run out upon the plains of the upper Gongola in groups of
picturesquely rounded hills. There is some reason also to believe that
the plateau is stepped or broken in the neighbourhood of Basak in the
Rukuba country, but this point must await further investigation.
The surface of the plateau reaches its highest elevation of about 4,100
feet in the neighbourhood of Ngell and Bukuru, whence the headwaters of
the Delimi, Sungo, Gongola, and Kaduna radiate approximately north,
south, east, and west. Of these rivers the Delimi ultimately joins the
Yo and falls into Lake Chad, the Gongola and Sungo join the Benue, and
the Kaduna the Niger. Thus the few square miles in the neighbourhood of
Ngell and Bukuru may rightly be claimed as the hydrographical centre of
the Protectorate (p. 3), and even the most casual observer cannot fail
to be impressed here with that peculiar character of the primary
watershed which has already been remarked in the case of the western
tributaries of the Niger and the northern tributaries of the Kaduna.
There is no group of rocky mountains, no rugged peak at the
hydrographical centre of the Protectorate, no lofty ranges forming the
watersheds between the radiating rivers: only an undulating, swampy,
alluvial plain, diversified by a few short, broken ridges and low kopjes
of granite boulders. Into these plains, however, the rivers which flow
north, west, and south are rapidly carving narrow rocky valleys, and
their descent to the lower plains is marked in every case by picturesque
waterfalls and narrow gorges cut back for considerable distances into
the plateau itself. The wooded gorge of the Delimi below Naraguta, the
steep waterfalls of the Kaduna between Kwoll and Miango, and the deep
rocky channel of the Kogin Rim above Assab afford striking evidence of
the activity of the rivers. Only in the east where the plateau inclines
gently towards the Gongola do the streams flow in sandy beds between
deep banks of alluvium, with broad stretches of swamp on either bank
wherever the slope is insufficient to drain the summer floods.
[Illustration: THE BAUCHI PLATEAU and the NASSARAWA TABLELAND.
MAP No. 2.
London. Macmillan & Co., Ltd.
_Face p._ 40.]
The Bauchi plateau, in the more restricted sense, may be taken to
include all those portions of the elevated plains which rise above 3,500
feet. Upon this definition the plateau is bounded on the south by the
continuous escarpment which stretches from Sura to Assab, and on the
west by a line drawn northward from Assab to Kwoll and Miango. Beyond
Miango the plateau is again limited by an escarpment as far as the
Jengre Hills, whence the boundary runs southward to Naraguta and thence
eastward along the higher escarpment behind Toro. The eastern boundary
of the plateau is formed by a line drawn approximately from south to
north from Kereng to Toro. The most striking feature of the greater part
of the plateau as thus defined, with the exception of the Rukuba country
to the north, is the bare and treeless aspect of the surface, which
assumes the character of undulating grassy downs extensively cultivated
in the neighbourhood of the towns and villages (Plate IX, Figs. 1, 2).
Only amidst the clusters of rocky hills which diversify the surface do a
few wind-worn trees bear witness to the former extent of the forest,
while round the bases of the hills and among the boulders on their
slopes are set the rectangular compounds of the pagan villages, whose
dark green hedges of prickly cactus add a pleasing touch of colour to
the mellow landscape. The low hills which rise from the plateau have
also a peculiarity all their own, which is to be directly correlated
with the greater diurnal variation in temperature. The turtlebacks and
domes and rounded hills of the lower plains are here conspicuously
absent, and in their place appear heaps of boulders and jagged ridges of
granite, with picturesque peaks and pinnacles and perched blocks
adorning their crests. Here and there, also, in the Rukuba and Kibyen
country in the west and in Sura in the south-east, more or less worn and
rounded volcanic cones rise above the general level of the plateau
(Plate X, Fig. 1). The craters of Kereng (Plate X, Fig. 2) in the south-
east, however, are remarkably well preserved. The surface of the plateau
itself is, moreover, deeply covered with drifted alluvium and provided
in places with a crust of surface ironstone through which the rivers and
streams have in many cases cut to the rock below. Above Assab the drift
has been largely removed from the surface, and between Rim and Woran
numerous grassy, flat-topped hills of red, gritty earth, capped by a
hard ferruginous crust, rise in places to a height of at least 300 feet
above the level of the plateau margin. These hillocks recall in
appearance the tabular sandstone hills of the Niger valley, and bear
striking witness to the former extent and thickness of the superficial
accumulations (Plate XI, Fig. 1). The broken, rocky character of the
marginal belt of plateau on the north in the neighbourhood of Zammagan,
Basak and Naraguta is probably also largely due to the removal of the
covering of drift which formerly obscured many of the irregularities of
the surface. Isolated hillocks of drift indeed are common throughout
Rukuba to the west of Jos and Naraguta (Plate XI, Fig. 2), while at
Basak they may be seen capping the very summit of the cliffs.
Beyond the limits of the plateau proper, a thinly wooded drift-covered
plain, in places somewhat broken and hummocky and diversified in the
usual manner by inselberge and scattered groups of granite hills and
drained by the headwaters of the Gongola, stretches eastward to the
meridian of Bauchi. Similarly, beyond the worn and rounded escarpments
and projecting spurs which form the northern margin of the plateau, an
undulating wooded plain, drained by the Delimi and its tributaries,
extends north-eastward towards the Kano border. The western watershed of
the Delimi valley runs along the hummocky drift-covered plain which
stretches northward between the Gura hills and the detached mass of the
Liruei-Kano hills, and thence through the rocky hilly country round
Tirkunya into the Ningi hills, which form the most striking feature of
the north-western portion of the province. This elongated mass of hills,
which stretches from Bura in the west to Ari in the east, is a typical
instance of those steep-sided and more or less tabular granite massifs,
of which examples have already been noted in the Ruruma hills of Zaria,
the Kagoro hills of Nassarawa and the Vere hills of Yola. The Ningi
massif reaches a higher elevation in the west than in the east, its
slopes are much rounded and incised by narrow valleys, its summit is
broken and hummocky with a scanty soil of disintegrated granite, while
wooded drift-covered plains stretch outward from its base towards Zaria
on the west, towards Kano and Katagum on the north, and towards the
Delimi valley on the east and south.
The surface of these wooded plains rises gently in the north to form the
low watershed between the valleys of the Delimi and the Shidya. The
headwaters of the Shidya rise in the tract of broken hilly country which
lies to the north and north-east of Bauchi, and forms in part the
northern watershed of the Gongola basin. Around Bauchi itself domes and
turtlebacks and groups of rounded hills, rising from the stony and
drift-covered plains, are particularly numerous and often remarkably
picturesque in their outlines, the lion couchant being one of the
commonest forms which the bare granite hills assume. (Plate XII, Figs. 1
and 2.) South of the Gongola the plains slope gently upward to the base
of the Jarawa and Kanna hills, becoming more and more broken and stony
as they approach the watershed of the Wase river. The granite massif of
the Wadai hills between Angass and Sura is only known along the northern
margin, while Angass[13] itself is a particularly broken and rugged
district separated from the Murchison Range by a series of rocky valleys
still largely unexplored. Between Angass and Kanna the high drift-
covered plains of Bauchi pass into a tract of broken country which is
drained by the headwaters of the Wase river and falls rapidly to the
plains of Yergum.[14] The line of fracture to the west which forms the
margin of the plateau appears to be replaced here by a simple flexure or
perhaps by a succession of worn and broken steps. Farther east rise the
Kanna and Kantana hills, with their projecting spur towards Kwankyam,
whose steep though worn escarpments interpose an ascent of 700 to 1,000
feet between the lower and higher plains. The western hills, which are
prolonged northward into the Jarawa country, are composed of crystalline
rocks, and the more prominent peaks possess the usual rounded outlines
of granite hills. The Kantana hills to the east, however, are
sedimentary in origin, and from a distance show the familiar tabular
outlines of horizontal sandstone hills, the narrow plateau on top being,
however, much eroded and incised. Eastward the escarpment appears to be
much stepped, and in the neighbourhood of Tukkur wheels northward to
form the eastern slope of the Jarawa hills which run out upon the plain
of the Gongola.
The eastern portion of the province is almost entirely covered with
sedimentary rocks. In the centre, a little to the south of the parallel
of Bauchi, broad plains stretch eastward from Goram and Lafiangale to
Deba Habe and the Gongola, bounded on the north by the broken sandstone
plateaux which are enclosed within the bend of the Gongola, and on the
south by the slopes of the Kudu valley, the rounded hills of Gateri and
the picturesque peaks of Tangale. In the west the plains are deeply
covered with sandy drift, through which the headwaters of the Kudu have
cut narrow canyon valleys into the sandstones below. Farther east the
summer rains render the plains for long distances almost impassable
swamps which drain imperceptibly east or west, and leave in the dry
season a gently undulating surface of black, gritty clay, baked and
fissured by the summer sun. To the north of the central plain and within
the bend of the Gongola lies a region of detached tabular masses of
elongated or irregular outline, together with groups of worn and rounded
sandstone hills, separated by stretches of sandy plain, presenting all
the familiar scenic features of the dissected sandstone plateaux of the
Niger. The narrow valley of the Gongola, between Deu and Gombe, bounded
by flat-topped ranges on either side, presents a marked contrast in
scenery to the upper course of the river above Baddera, where it threads
its way over the high plains of Bauchi between turtlebacks and domes of
granite. Below Gombe, however, the valley opens out and the river flows
as far as Nafada through an open sandy plain, diversified by occasional
flat-topped sandstone hills. Between Nafada and Ashaka the channel winds
between detached hills and short tabular ranges which rise from an
undulating, thinly-wooded plain, while below Ashaka the river enters the
deeply drift-covered plain which stretches from the base of the Tilde
and Dukul hills on the west to the foot of the escarpment of the Barbur
plateau in Bornu on the east. As far as Jurara and Deba Filani the plain
is thickly populated, well-cleared and cultivated; southward, however,
within the Habe country, the scattered villages are separated by longer
stretches of bush, while the plain is diversified by hummocks of
sandstone and worn hillocks of basalt with the intervening
irregularities of the surface deeply buried in drift. Beyond Deba Habe,
the plain of the Gongola forms the eastward continuation of the central
plain of Bauchi, whose sandy and swampy surface stretches southward to
the base of the Tangale hills.
The south-eastern portion of the province is occupied in part by the
upper valley of the Kudu river and in part by the extensive mass of
hills which, with the exception of the outer margin around Gateri,
Tangale, and Waja, is still largely unentered and unexplored. A series
of narrow valleys, terminated by canyon-like gorges, have been cut by
the headwaters of the Kudu into the elevated plains of Pali and
Lafiangale. The difference in level between the upper plains and the
river bed is greatest in Dugari in the west, where the streams flow in
narrow flat-bottomed valleys, bounded by perpendicular walls of white
sandstone three to five hundred feet in height. From the cliffs above
Tongolan the scenery recalls in miniature the chasms, amphitheatres, and
canyons of Colorado, with their promontories and projecting buttresses,
steep slopes and vertical ledges, while south-eastward towards Yuli the
remnants of a lower plateau mark a former pause in the activity of the
river. Farther east, by Panguru and Putu, the relative height of the
upper plains decreases, the sandstones become broken and inclined, and
the tributary valleys are bounded, not by cliffs, but by rounded, drift-
covered slopes leading upward to the higher undulating plains. The
folded sandstones of Gateri and Ligri give rise to a group of rounded
hills deeply incised by narrow valleys and backed by the ridges and
peaks of the unexplored Wurkum and Pero hills, which stretch north-
eastward towards the Gongola. From Gateri northward to Putu the track
leads over somewhat broken country, while eastward from Putu to Tangalto
stretch open, undulating, swampy plains, diversified only by occasional
conical stumps of basalt.
PLATE IV
[Illustration: A GRANITE MOUNT NEAR ABUJA.]
[Illustration: THE MARGIN OF THE NASSARAWA TABLELAND FROM JAGINDE.]
The tract of country which lies between Tangale and the Gongola is one
of the most picturesque within the Protectorate. The hills rise in
detached groups from an irregular hummocky plain, and form the advanced
guard of the belt of lofty highlands which intervene between the
northern plains and the Benue. While the whole district may be spoken of
generally as Tangale, the Tangale tribe itself occupies a very
restricted area and is lodged within only the westernmost group of
hills, the successive groups to the east and south being inhabited by
the kindred but mutually hostile tribes of Chongwom, Ture, Awok, Tula,
and Waja. Tangalto and Tall, the strongholds of the Tangale tribe, are
set on the slopes of rounded granite hills, picturesquely pierced by
worn pillars of trachyte and basalt, and separated by a narrow
undulating plain from the neighbouring group of granite hills inhabited
by the pagans of Chongwom and Kaltungo. Beyond Chongwom the character of
the scenery entirely changes. In place of the rounded crystalline hills
there rise precipitous and more or less tabular masses of well-bedded
sedimentary rock, forming natural fortresses in the midst of an
undulating park-like plain, diversified by knobs and hummocks and
standing rocks of sandstone (Plate XIII, Fig. 1). At times the summit
ridges are gently curved and the hills are bounded on one side by a
steep escarpment and on the other by a dip slope sinking gradually to
the plains below, while the whole landscape is dominated by the Ture or
Tangale Peak, a picturesque pillar of trachyte rising from a worn and
flattened basal cone of sandstone (Plate XIII, Fig. 2). Eastward, around
Jelengu and Reme, somewhat similar pillars of volcanic rock project here
and there above the sandstone hills, while the worn escarpments of Waja
appear to be continuous with those which form the western boundary of
the lower Gongola valley. The country which lies to the south of Tangale
and Waja is quite unknown. From the upper slopes of the Ture Peak, a
second distant range of hills can be seen running parallel with the
jagged ridge in the foreground, and it is probable that, instead of a
mass of hills or a continuous plateau, there is within this unexplored
land a succession of broken valleys and rocky ridges, forming one of the
last strongholds of paganism within the Protectorate.
_The Northern Provinces.—Bornu, Kano, and Sokoto._
The southern portion of Bornu, which lies immediately east of the
Gongola, presents, so far as the character of its physical features is
concerned, a greater affinity with the central provinces of Bauchi and
Zaria than with the northern Hausa States or with the northern portion
of Bornu itself. The valley of the Gongola to the east of the river is
more broken and hummocky than it is to the west. The sandstones are much
faulted and variously inclined and form belts of rocky plain between the
swampy valleys of the tributary streams. Here and there, as at Wuyo and
Gulani, a circle of jagged ridges forms a natural battlement round a
pagan town, or, as at Balbea, a flattened sandstone hill forms a natural
stronghold in the midst of the plain. More striking, however, are the
level crests, the dip slopes and the steep escarpments of the Bima and
Wadi hills, which form the landmarks of the Gongola plain from Ashaka to
Wuyo. From Gulani north-westward to Ashaka stretches an extensive
undulating plain, broken only by an occasional ridge of sandstone, with
black swamp earth covering all the minor irregularities of the surface
and creeping up the slopes of the sandstone hills themselves. Eastward
the broken plain of the Gongola is bounded by the worn escarpment of the
Barbur volcanic plateau which becomes higher towards the north, and
between Bilaraba and Dukshi is fringed with a series of flat-topped and
conical outliers of basalt. To the east of Gulani and Balbea the ascent
to the plateau is over basal sandstones capped by black volcanic rock.
Farther north, however, in the neighbourhood of Dukshi, the escarpment
is entirely composed of basalt and rises from an irregular crystalline
floor. The summit of the plateau is broken and rocky in the west, deeply
trenched by the tributary streams of the Gongola, and diversified by
numerous worn and rounded cones of ash and lava. Eastward towards
Buratai the plateau descends by a series of low rocky steps separated by
drift-covered levels to the plains of Hong and Ajigin, whose deep
covering of dark gritty clay, hard and fissured in the dry season, forms
an almost impassable swamp in the rains. In the south-east, towards Biu
and the little-known Burra country, the volcanic cones become higher and
more conspicuous, while the surface of the plateau, according to native
information, becomes much dissected and broken up into narrow plains and
rocky valleys.
Two tracts of hilly country, separated by the swamps of Hong and Ajigin,
lie respectively to the north-west and north-east of the volcanic
plateau. The worn and flattened hills of sandstone and ironstone, which
stretch westward from Buni and Ligdar towards Gabai, pass northward into
the high, drift-covered plains of Mutwe and Gujba, which form the
watershed between the Gongola and Lake Chad. In the east the Tagum and
other groups of flat-topped hills around Lua, Ndufa, and Korode
represent the remains of a sandstone plateau once continuous with the
hills of Buni and Ligdar across the swamps of Ajigin. To the north and
north-east of the Tagum hills stretch the great wooded plains of Bornu,
with their gently undulating surface sloping imperceptibly towards Lake
Chad, and with not a single hill nor even a hummock of boulders to
relieve the monotony of the scenery. To the south-east of the Tagum
hills the sandstones run out upon a crystalline floor which stretches
southward into Yola province, with its surface diversified only at long
intervals by island mountains and groups of granite hills.
The plains of Bornu, which stretch northward from the rocks of Chibuk
and the Tagum hills to Lake Chad and the river Yo, are in the east so
imperfectly drained that extensive tracts of their surface become marshy
and swampy during the rainy season. The swamps reach their greatest
development in the valley of the Yedseram and in the immediate
neighbourhood of Chad, where the whole country is flooded after the
rains. Barth[15] has described in a sufficiently vivid manner the
featureless and cheerless aspect of the swampy plains to the south and
south-east of Chad. Along the caravan road from Maidugari to Kukawa
transverse stretches of swamp land (firki) alternate with belts of
slightly higher ground, hard and smooth on the surface, or thinly coated
with loose yellow sand or dark grey loam. The character of the
vegetation reflects immediately the changes in the nature of the surface
soil. In the dry season, after the grass is burnt, the cracked and
fissured surface of the firki land is absolutely bare and treeless, the
hard and smooth surfaces of sandy clay are covered with thin mimosa
bush, while the stretches of loose sandy loam support a more abundant
growth of trees and scrub. The ancient dunes and the undulating sandy
plains which bound the northern basin of Chad support an open forest
growth, while recent accumulations of blown sand are now found only
within the towns themselves, or in places which have been cleared of
forest for purposes of cultivation.
The Maidugari river, which rises on the Yola border and loses itself in
swamp a few miles to the north of Maidugari, has cut deeply into the
superficial sandy drift in the neighbourhood of Maidugari and Maifoni
and formed a comparatively narrow valley with steeply-rounded slopes.
From Maifoni a gently rolling plain stretches westward to Gujba, with
occasional thick-stemmed kukas rising prominently above the low growth
of scrubby trees and prickly mimosa which covers the surface, and with
here and there a dry “tubka” or shallow swampy hollow forming an open
space within the forest. At Murguba, and again at Gujba, the plain is
broken by shallow water-courses, bounded by low and ill-defined ridges
of rising ground. These extended swampy hollows are flooded during the
rains, and in the dry season marked by a line of wells and occasional
pools separated by sandy bars. Beyond Gujba the rolling plains become
again marked by a rapid alternation of sandy rising ground and clayey
shallows draining southward in the rains. Between Chumga and Abakri,
however, rock begins to appear in places on the surface of the drift-
covered undulations which separate the swampy valleys, while a few
isolated flat-topped or rounded hills are scattered over the plains.
From Abakri can be seen to the west the long flattened and rounded
ridges and tabular hills, half buried in sandy drift, which introduce
the Kerri Kerri plateau. Daura and Durua are set within this broken
country, each at the base of a low flat-topped range of ironstone hills,
while the track leads over a succession of stony ridges and shallow
cultivated valleys to the continuous plateau surface which is reached
about half-way between Durua and Momdo. The plateau itself is no higher
than the summits of the marginal hills, which with their drift-filled
valleys represent merely the dissected eastern front of the tableland.
The surface of the plateau, at first thinly wooded and in places
somewhat stony, passes westward into the open sandy undulating plains
around Potiskum, which fall away gently to the north and west into the
valley of the Kogin Shidya. Here and there a low hill or a rounded ridge
of sandstone or ironstone rises above the general level, with the sandy
drift which obscures all the minor irregularities of the surface deeply
banked against its slopes.
The Kerri Kerri plateau, like the tableland of Nassarawa and the
elevated plains of Bauchi, is not a true plateau in the strict sense of
the term, but rather an inclined plane, bounded by more or less worn
escarpments on the south and passing gradually northward into the plains
of Ngizem. The escarpments which stretch from the neighbourhood of Daura
south-westward to the provincial boundary reach their greatest elevation
behind Dozi, Lewe, and Gamari to the north-west of Nafada, where
precipitous cliffs of white sandstone 500 to 600 feet high rise abruptly
from the sandy plains which stretch southward to the Gongola. The
escarpment, however, is in no sense a continuous one, for, as already
noted in the neighbourhood of Daura, the margin of the plateau has been
much cut up and dissected, especially in the east, into a system of more
or less detached flat-topped ranges and tabular masses separated by
narrow valleys or by short stretches of open plain.
Westward where the escarpment is higher, as in the neighbourhood of Dozi
and Kadi, the cliffs are furnished with the characteristic buttresses
and indentations of horizontal sandstone rocks, while the margin of the
plateau is fringed with a series of detached tabular and conical
outliers of varying size and elevation (Plate XIV, Fig. 1), the larger
of which form natural strongholds for pagan villages.[16] The most
remarkable feature, however, about the margin of the plateau is that,
behind the fringing belt of detached ranges and outlying groups of
hills, the main mass of the plateau has been grooved or incised by a
series of narrow flat-bottomed trench-like valleys, bounded by
perpendicular walls of white sandstone and notched and indented by
lateral gullies (Plate XIV, Fig. 2). For long distances the narrow
valleys preserve a very constant breadth, while frequently they turn
abruptly at right angles or are joined by lateral valleys of similar
character which unite the whole series into an interlacing system
through which it is possible to travel from Daura to Zai without once
ascending to the level of the plateau above. At their upper ends the
valleys rapidly contract and run out upon the plateau as steep and rocky
gullies. Their floors, like the surface of the plateau above, are well
cleared for cultivation and studded with scattered trees, while the
villages are set aloft on the margin of the cliffs overlooking the wells
in the valley below.
Beyond the western boundary of Bornu the escarpments die down, and the
drift-covered surface of the plateau falls gently to the swampy valley
of the Kogin Shidya. The last trace of the sandstones of Kerri Kerri is
found in the low hills of conglomerate and grit around Hardawa, while
twenty miles to the north according to native information the sandstones
disappear in the neighbourhood of Lise under the sands and swamps of
Katagum. Beyond Hardawa begin the undulating plains of Hausaland (pp.
21, 38), which stretch westward, to the north of the Ningi massif,
through the heart of Kano and the north-eastern portion of Zaria into
Kontagora and Sokoto. Here and there a heap of granite boulders or an
isolated group of rounded hills, as at Shira, Fagam and Kila, rise out
of the red sandy drift which is deeply banked against their slopes, and
which elsewhere effectually buries the irregularities of the crystalline
floor. Occasionally a smooth and rounded surface of gneiss or granite
outcrops level with the plain, while the rivers which flow in broad,
shallow and ill-defined valleys, indistinguishable at a distance from
the rest of the plain, have here and there succeeded in cutting their
channels through the sandy drift to the solid rock below. Where
uncultivated the plains are covered with prickly mimosa bush, or with
trees well spaced or in bushy clumps with open grass around. The farm-
land, however, is well cleared and comparatively bare with a few large
trees scattered here and there amongst the furrows, while the fallow is
thickly covered with tall aromatic grass and low scrubby trees of a few
seasons’ growth.
From Jemaari north-eastward to Katagum, and thence westward to the
immediate neighbourhood of Kano, not a single rock is anywhere exposed,
and not a single block or boulder or even a pebble of quartz is to be
found in the sandy loam which covers the surface. North of Jemaari the
track leads through gently undulating country presenting the usual
alternations of farm-land and thinly wooded plain. Between Itas and
Murmur the surface becomes in places quite hummocky with ancient dunes
in the form of low rounded ridges of loose sandy drift, extended
approximately east and west, rising in succession upon the level plain
and bearing witness to the former prevalence of desert conditions.
Around Katagum the drainage is so imperfect that long stretches of the
plain are under water in the rains, while westward beyond Kwotolu the
surface resumes its undulating aspect with its alternation of sandy
rising ground and clayey shallows. Here and there, as at Koya, a rounded
ridge of loose sand, now covered with grass and scattered trees, affords
evidence of the former activity of the wind, while in places in the
hollows are small sheets of fresh water forming lakes which are more or
less permanent throughout the year.
Around Kano and north-westward towards Katsina the open undulating plain
presents all the characteristic features of a crystalline floor. For
long distances round the towns the red sandy loam which covers the
surface has been cleared of all but the larger trees and subjected for
generations to intense cultivation. Here and there around Kano smooth
surfaces of rock appear level with the plain, or rise into low rounded
turtlebacks or heaps of granite boulders. The two prominent tabular
hills of weathered diorite, Dala and Kogon Dutsi,[17] within the walls
of Kano, have a peculiar interest of their own which will be related in
the sequel (p. 201). Northward between Kano and Kazaure the undulating
sandy plain is diversified only by the low flat-topped hillocks of
earthy grit and conglomerate in the neighbourhood of Sai and Ingogo and
by the broken ridges of amethystine quartz which rise from the plain
immediately south of Kunchi. Kazaure is set in the midst of rocky ridges
of blue quartzite with red sandy drift filling up the valleys and banked
against the slopes of the hills. Around Rauni rise low extended
flattened ridges, which appear to be composed throughout of dark red
vesicular ironstone. At Tummas, half way to Ingawa, low granite knobs
and heaps of boulders project above the surface, but from Ingawa north-
westward to Katsina the undulating plains are featureless, with no
prominent granite hills or kopjes to break the monotony of the
landscape. Smooth surfaces of rock are here and there exposed level with
the plain or in the channels of the streams, but otherwise the deep
sandy drift which covers the surface effectually obscures all the minor
irregularities.
Around Katsina both sandstones and granites are exposed upon the surface
of the plain, but it is not until the neighbourhood of Kurefi is reached
that a decided change takes place in the character of the scenery. From
Kurefi to Runka the track leads through rocky granite country which
assumes its wildest aspect in the neighbourhood of Tummo, where the
landscape, as far as one can see, is made up of an assemblage of low
rounded hills, domes, tors, heaps of boulders, perched blocks and smooth
surfaces of granite, with no particularly high or prominent peaks. On
the margin of the mass near Kurefi and Runka the aspect of the country
is smoother; the turtlebacks and rounded hills are separated by narrow
stretches of plain, and often half-buried under the sandy drift which is
banked up against their slopes. From Runka south-westward to Kotorkoshi,
and thence north-westward to Karakai, the landscape assumes its familiar
aspect of a gently undulating thinly-wooded surface, diversified by
isolated groups of granite hills which, at Duru and Kotorkoshi, rise
abruptly and picturesquely from the drift-covered plain. A belt of
broken hilly country stretches N.N.E. and S.S.W. between Karakai and
Maradu, parallel with the strike of the quartzites, phyllites, and
gneisses out of which the hills are carved. Immediately beyond Maradu
knobs and hummocks of volcanic agglomerate project from the surface of
the plain, while northward the track leaves the hummocky crystalline
floor in the neighbourhood of Gora and follows the level swampy plain of
the Gulbin Gandi as far as Dankaiwa. At Dankaiwa, in the cliff which
faces the river, is the first exposure of the red earthy sandstones of
Sokoto, while at Dampo, a little farther on, the first flat-topped
sandstone hill rises above the sandy plain. From Dampo the track again
runs along the swampy valley of the river as far as Rara, whence it
leads across undulating park-like plains to the broken sandstone hills
of Sokoto.
The northern and western portions of Sokoto province, which consist of a
dissected plateau of horizontal sandstones, possess in general all the
familiar scenic features of such a formation as already described from
other parts of the Protectorate. The apparent differences are
differences more in degree than in kind. Like the Niger above Lokoja,
the Benue in its lower and upper course and the Gongola above Gombe, the
Gulbin Kebbi or Sokoto river flows in a broad flat-bottomed trench-like
valley between two steep and worn escarpments, which lead up to the
plateau on either side. The breadth of the valley of the Gulbin Kebbi
is, however, out of all proportion both to the height of the bounding
walls and to the volume of the river itself. The floor of the valley is
usually several miles in breadth, while the cliffs on either side rarely
reach 200 feet in height. In the rainy season a sluggish flood covers
the bottom of the valley, but in the dry season the river is represented
by one or more diminutive streams, which disappear from time to time in
stretches of swamp. The continuity of the flat-topped escarpments is
much broken by lateral valleys, and here and there the vertical walls
are replaced for long distances by steeply-rounded rising ground. The
tributaries of the Gulbin Kebbi, where they flow through sandstone
country, are likewise bounded by worn and broken escarpments. Similar
broad flat-bottomed valleys with diminutive streams are common also
within the French Sudan to the north of Sokoto, and are there generally
known as “dallols.” Of them all, however, the Gulbin Kebbi possesses the
greatest volume of water, which is contributed practically entirely by
its numerous southern affluents which rise on the high and well-watered
plains on the borders of Kano, Zaria, Kontagora and Sokoto.
PLATE V
[Illustration: WORN VOLCANIC CONES NEAR AWE.]
[Illustration: THE WASE ROCK.]
The plateau areas between the larger valleys are themselves much
dissected, especially in the east and north, by the smaller tributary
streams. In the west there are some fairly extensive stretches of
continuous tableland, whose gently undulating and thinly-wooded surface
is diversified by occasional flat-topped and conical hills, the relics
of a former plain which has now been almost entirely removed in the
course of denudation. To the north and north-east of Sokoto the
irregularities of the dissected plateau are softened in contour by
accumulations of blown sand which covers the floors of the smaller
valleys and creeps up their lateral slopes, rounding off the steeper
cliffs of the flattened ridges on either side.
[Footnote 1: Mungo Park; Denham and Clapperton; R. and J. Lander; Laird
and Oldfield; Allen and Thomson; Baikie; Crowther; Barth; Vogel;
Passarge; Lenfant; Lugard; Wallace; Boyd-Alexander.]
[Footnote 2: “Hausaland,” in the general sense of the term, may be taken
to include the provinces of Sokoto, Kano, Kontagora, Zaria and Bauchi.]
[Footnote 3: _Cf._ Laird and Oldfield, _Expedition to Africa_, 1837, p.
136. The hills between Itobe and Igbo are here erroneously described as
the eastward prolongation of the Kong Mountains.]
[Footnote 4: _Cf._ Vandeleur, _Geographical Journal_, X, 1897, p. 349.]
[Footnote 5: _Vide_ Lenfant, _Le Niger_, 1905, illus., pp. 72, 73.]
[Footnote 6: Lenfant, _op. cit._, p. 78 _et seq._]
[Footnote 7: Boyd-Alexander, _From the Niger to the Nile_, 1908, p. 47.]
[Footnote 8: An excellent illustration of this peculiar type of scenery
(Inselberglandschaft) is given by Bornhardt, _Deutsch-Ost-
Afrika—Géologie_, Bd. VII, 1900, Taf. 3, p. 30.]
[Footnote 9: Erroneously designated lava by the earlier explorers.]
[Footnote 10: _Cf._ Boyd-Alexander, _From the Niger to the Nile_, 1908,
p. 86.]
[Footnote 11: _Cf._ Boyd-Alexander, _op. cit._, p. 46.]
[Footnote 12: _Cf._ Whitlock, “The Yola-Cross River Boundary
Commission,” _G. J._, XXXVI, 1910, p. 426.]
[Footnote 13: _Cf._ Boyd-Alexander, _op. cit._, p. 98.]
[Footnote 14: _Ibid._, p. 94.]
[Footnote 15: Barth, _Central Africa_, 1857, II, p. 355.]
[Footnote 16: _Cf._ Boyd-Alexander, _From the Niger to the Nile_, pp.
112, 164.]
[Footnote 17: _Cf._ Barth, _Central Africa_, 1857, p. 96.]
CHAPTER II
CRYSTALLINE ROCKS
Distribution of the crystalline rocks. Typical traverses. The harder and
softer gneisses. The Jebba quartzites: the phyllites and slaty schists
of the Niger valley; the sheared trachytes of Bussa; the Ngashki
phyllites; replacement of the softer gneisses by the harder banded
types. The gneisses and schists of Ilorin; the quartzites of the Orissa
hills; the stanniferous pegmatites of Eri. The muscovite schists of
Northern Kabba; the quartzites of Lukke; the crystalline limestone
between Jakura and Wa; the mica schists of Sequarre; the magnetite and
hæmatite schists of Eastern Kabba; the Igbo limestone. The phyllites and
schists of Sokoto province; the volcanic agglomerate of Maradu; the blue
quartzite of Kazaure; the diorites of Kano; Mounts Dala and Kogon Dutsi;
the gneisses and schists of north-eastern Kontagora; the Zungeru belt of
phyllites and schists; auriferous quartz reefs; the quartzites and
schists of Eastern Zaria; the gneisses and granites of Abuja; the
tourmaline rocks of Darroro; the mica schists of Gwombe; the banded
gneisses of Bauchi province; the granites of the Murchison Hills; the
later intrusions. The inliers of Arofu; the granites and gneisses of
southern Muri; the Vere Hills; exfoliation in the Kilba Hills; the
crystalline rocks of Bornu.
While crystalline rocks undoubtedly everywhere form the foundation of
the Protectorate, there are extensive tracts over which the later
sedimentary rocks obscure the underlying granites, gneisses, and
schists. The largest area over which these crystalline rocks are exposed
is that which occupies the centre of the Protectorate and extends from
the Niger in the west to beyond Bauchi in the east, and from Nassarawa
in the south to the neighbourhood of Katsina in the north. The major
portion of the provinces of Kabba, Ilorin and Borgu to the west of the
Niger also possess a crystalline floor, while similar rocks cover a
narrow strip on the southern border of Muri and Yola, as well as a
considerable tract of country to the east of the Gongola, lying partly
in Yola and partly in Bornu.
_Typical Traverses._
The following typical traverses show the character of the exposures
along the tracks.
I. Filelin (near Lokoja) to Ohoto:
9.20 A.M.— Left Filelin.
9.34 „ Blocks of ferruginous sandstone and grit.
9.38 „ Masses of biotite pegmatite; large felspars often
graphic.
9.40 „ Fine-grained, non-foliated reddish biotite granite with
streaks and veins of graphic biotite pegmatite. The
granite at places on the margin follows the foliation of
the adjoining biotite gneisses, in places crosses the
foliation, or is in part injected into the gneiss. The
biotite gneiss is often folded and distorted; in places
there is an alternation of dark bands of biotite gneiss
with lighter coloured felspathic layers. The foliation
is much disturbed, but in a general way E.N.E. and
vertical. The gneiss is cut by granite and pegmatite
veins and dykes.
9.45 „ Reddish granite continued. In places the granite shows
distinct banding and alternation of coarse and fine
layers; sometimes banded with pegmatites.
9.50 „ Same pink granite; but here an irregular mixture of
coarse and fine material with in places knots of coarse
granite in a fine grained matrix.
10.0 „ Small granite knobs on right.
10.3 „ Sandstones.
10.10 „ Biotite gneiss, strike N.E.–S.W., foliation dip 40° N.,
cut by coarse pegmatites as before; in places
interfoliated bands of segregation pegmatite.
10.15 „ Soft biotite gneisses.
10.30 „ Large blocks of pink granite and pegmatite.
10.40 „ Granite piercing hard white biotite gneiss with knots of
amphibolite. Strike of gneisses N. 35° E., foliation dip
N.W. There is a sharp junction between the granite and
gneiss, but no chilled margin.
10.50 „ Granite.
11.0 „ No exposures.
11.30 „ Extensive mass of coarse-grained biotite gneiss, crossed
by pegmatite veins and dykes of coarse red granite with
large felspars.
11.35 „ Biotite augen-gneiss with felspars sometimes two inches
long; crossed by veins of fine red granite or aplite.
11.40 „ No exposures.
12.30 P.M.— Bare surface of augen-gneiss level with the plain.
12.40 „ Dyke or sheet of fine grained reddish granite showing
distinct foliation.
12.45 „ Fine grained and finely banded biotite gneisses crossed
and injected by granite veins.
12.50 „ Sandstones.
1.15 „ Ohoto.
II. Jakura to Wa (north side of Mimi Valley).
6.30 A.M.— Left Jakura hill; on brow of hill quartz schist, strike
N. 10° W., foliation vertical; at foot of hill fine
grained pink granite with pegmatite, passing into
friable pink granite with large crystals of graphic
quartz and felspar in a finer matrix.
6.55 „ Soft biotite gneisses, strike N.N.E., dip W.N.W.
6.58 „ Band of amphibolite, dip unascertainable, followed by
soft biotite gneisses. Pebbles of hornblende epidote
schist.
7.12 „ Bare exposure of red pegmatite dyke cutting fine grained
felspathic gneiss, with in places a sharp junction and
in others not.
7.20 „ Quartz schist.
7.35 „ Magnetite hornblende schist, strike N. 10° W., foliation
dip practically horizontal.
7.40 „ Quartz hæmatite schist, dip unascertainable.
8.0 „ Massive and granular quartzite and quartz schist.
8.15 „ Biotite gneiss.
8.30 „ Quartz-muscovite schist, strike N.N.E., dip low to
W.N.W.
8.35 „ Pebbly muscovite schist, strike N.–S., foliation
vertical or highly inclined.
8.45 „ Pegmatites.
8.50 „ White marble forming rounded knobby hills cut by
pegmatite veins and enclosing streaks and veins of
quartz-epidote-calcite-idocrase rock on right hand; on
left the marble is foliated, with folia of pyrites and
knots of quartz; strike of foliation N. 10° E., dip 10°
W.
9.5 „ Marble ends.
9.8 „ No exposures; grass land.
9.15 „ Quartzites.
9-35 „ Soft biotite gneiss; foliation generally vertical;
strike N.N.E., dip vertical or high towards W.
9.50 „ Garnetiferous biotite gneiss with quartz segregations;
folia crumpled and contorted; strike generally N.–S.
10.10 „ Garnetiferous biotite gneiss as before; folia
practically horizontal.
10.25 „ Soft micaceous schists pierced by granite; strike N. 35°
E., dip S.E.
10.35 „ Pink granite in places foliated; graphic pegmatites on
slope of Wa hill.
10.45 „ Wa. On top of hill white mica schists with magnetite
knots, strike N.–S., dip 20° W.; cut by
quartz-muscovite-magnetite pegmatites.
III. Olle to Sura (Central Kabba).
6.20 A.M.— Left Olle.
6.25 „ Quartz schists and quartz-muscovite schists, strike N.
40° E., dip 55° W.
6.27 „ Soft fine-grained quartz-muscovite schists, strike N.
10° E., dip 70° W.
6.35 „ Muscovite schists, strike N. 30° W., foliation vertical.
6.40 „ Thick dyke of graphic quartz and felspar, with crystals
of tourmaline.
7.5 „ Fine grained white granite.
7.25 „ Coarse white granite in river bed.
7.30 „ No exposures.
8.10 „ Micaceous gneiss, strike N. 35° E.; much folded and
contorted with streaks and knots of pegmatite, probably
proceeding from a thick intrusive mass of quartz-felspar
pegmatite which adjoins the gneiss.
8.35 „ Muscovite schists, strike N.–S., foliation vertical.