Nature, Origin, and Age of the Loess of the Rhine and Danube.
Impalpable Mud produced by the Grinding Action of Glaciers.
Dispersion of this Mud at the Period of the Retreat of the
great Alpine Glaciers.
Continuity of the Loess from Switzerland to the Low Countries.
Characteristic Organic Remains not Lacustrine.
Alpine Gravel in the Valley of the Rhine covered by Loess.
Geographical Distribution of the Loess and its Height above the Sea.
Fossil Mammalia.
Loess of the Danube.
Oscillations in the Level of the Alps and lower Country required to
explain the Formation and Denudation of the Loess.
More rapid Movement of the Inland Country.
The same Depression and Upheaval might account for the Advance
and Retreat of the Alpine Glaciers.
Himalayan Mud of the Plains of the Ganges compared to
European Loess.
Human Remains in Loess near Maestricht, and their probable
Antiquity.
NATURE AND ORIGIN OF THE LOESS.
Intimately connected with the subjects treated of in the last chapter,
is the nature, origin, and age of certain loamy deposits, commonly
called loess, which form a marked feature in the superficial deposits
of the basins of the Rhine, Danube, and some other large rivers draining
the Alps, and which extend down the Rhine into the Low Countries, and
were once perhaps continuous with others of like composition in the
north of France. [35]
It has been reported of late years that human remains have been detected
at several points in the loess of the Meuse around and below Maestricht.
I have visited the localities referred to; but, before giving an account
of them, it will be desirable to explain what is meant by the loess, a
step the more necessary as a French geologist for whose knowledge and
judgment I have great respect, tells me he has come to the conclusion
that "the loess" is "a myth," having no real existence in a geological
sense or as holding a definite place in the chronological series.
No doubt it is true that in every country, and at all geological
periods, rivers have been depositing fine loam on their inundated plains
in the manner explained above in Chapter 3, where the Nile mud was
spoken of. This mud of the plains of Egypt, according to Professor
Bischoff's chemical analysis agrees closely in composition with the
loess of the Rhine.*
(* "Chemical and Physical Geology" volume 1 page 132.)
I have also shown when speaking of the fossil man of Natchez, how
identical in mineral character and in the genera of its terrestrial and
amphibious shells is the ancient fluviatile loam of the Mississippi
with the loess of the Rhine. But granting that loam presenting the same
aspect has originated at different times and in distinct hydrographical
basins, it is nevertheless true that during the glacial period the Alps
were a great centre of dispersion, not only of erratics, as we have seen
in the last chapter, and of gravel which was carried farther than the
erratics, but also of very fine mud which was transported to still
greater distances and in greater volume down the principal river-courses
between the mountains and the sea.
MUD PRODUCED BY GLACIERS.
They who have visited Switzerland are aware that every torrent which
issues from an icy cavern at the extremity of a glacier is densely
charged with an impalpable powder, produced by the grinding action to
which the subjacent floor of rock and the stones and sand frozen into
the ice are exposed in the manner before described. We may therefore
readily conceive that a much greater volume of fine sediment was swept
along by rivers swollen by melting ice at the time of the retreat of the
gigantic glaciers of the olden time. The fact that a large proportion
of this mud, instead of being carried to the ocean where it might have
formed a delta on the coast or have been dispersed far and wide by the
tides and currents, has accumulated in inland valleys, will be found
to be an additional proof of the former occurrence of those grand
oscillations in the level of the Alps and parts of the adjoining
continent which were required to explain the alternate advance and
retreat of the glaciers, and the superposition of more than one boulder
clay and stratified alluvium.
The position of the loess between Basle and Bonn is such as to imply
that the great valley of the Rhine had already acquired its present
shape, and in some places, perhaps more than its actual depth and width,
previously to the time when it was gradually filled up to a great extent
with fine loam. The greater part of this loam has been since removed,
so that a fringe only of the deposit is now left on the flanks of the
boundary hills, or occasionally some outliers in the middle of the great
plain of the Rhine where it expands in width.
These outliers are sometimes on such a scale as to admit of minor hills
and valleys, having been shaped out of them by the action of rain and
small streamlets, as near Freiburg in the Breisgau and other districts.
FOSSIL SHELLS OF THE LOESS.
[Illustration: Figures 44, 45, and 46]
(FIGURE 44. Succinea oblonga.)
(FIGURE 45. Pupa muscorum.)
(FIGURE 46. Helix hispida, Lin.; H. plebeia, Drap.)
The loess is generally devoid of fossils, although in many places they
are abundant, consisting of land-shells, all of living species, and
comprising no small part of the entire molluscous fauna now inhabiting
the same region. The three shells most frequently met with are those
represented in the annexed figures (44, 45 and 46). The slug, called
Succinea, is not strictly aquatic, but lives in damp places, and may be
seen in full activity far from rivers, in meadows where the grass is wet
with rain or dew; but shells of the genera Limnaea, Planorbis, Paludina,
Cyclas, and others, requiring to be constantly in the water, are
extremely exceptional in the loess, occurring only at the bottom of the
deposit where it begins to alternate with ancient river-gravel on which
it usually reposes.
This underlying gravel consists in the valley of the Rhine for the most
part of pebbles and boulders of Alpine origin, showing that there was a
time when the rivers had power to convey coarse materials for hundreds
of miles northwards from Switzerland towards the sea; whereas at a later
period an entire change was brought about in the physical geography of
the same district, so that the same river deposited nothing but fine
mud, which accumulated to a thickness of 800 feet or more above the
original alluvial plain.
But although most of the fundamental gravel was derived from the Alps,
there has been observed in the neighbourhood of the principal mountain
chains bordering the great valley, such as the Black Forest, Vosges,
and Odenwald, an admixture of detritus characteristic of those several
chains. We cannot doubt therefore that as some of these mountains,
especially the Vosges, had during the glacial period their own glaciers,
a part of the fine mud of their moraines must have been mingled with
loess of Alpine origin; although the principal mass of the latter must
have come from Switzerland, and can in fact be traced continuously from
Basle to Belgium.
GEOGRAPHICAL DISTRIBUTION OF THE LOESS.
It was stated in the last chapter that at the time of the greatest
extension of the Swiss glaciers the Lake of Constance and all the other
great lakes were filled with ice, so that gravel and mud could pass
freely from the upper Alpine valley of the Rhine to the lower region
between Basle and the sea, the great lake intercepting no part of the
moraines whether fine or coarse. On the other hand the Aar with its
great tributaries the Limmat and the Reuss does not join the Rhine till
after it issues from the Lake of Constance; and by their channels a
large part of the Alpine gravel and mud could always have passed without
obstruction into the lower country, even after the ice of the great lake
had melted.
It will give the reader some idea of the manner in which the Rhenish
loess occurs, if he is told that some of the earlier scientific
observers imagined it to have been formed in a vast lake which occupied
the valley of the Rhine from Basle to Mayence, sending up arms or
branches into what are now the valleys of the Main, Neckar, and other
large rivers. They placed the barrier of this imaginary lake in the
narrow and picturesque gorge of the Rhine between Bingen and Coblenz:
and when it was objected that the lateral valley of the Lahn,
communicating with that gorge, had also been filled with loess, they
were compelled to transfer the great dam farther down and to place it
below Bonn. Strictly speaking it must be placed much farther north, or
in the 51st parallel of latitude, where the limits of the loess have
been traced out by MM. Omalius D'Halloy, Dumont, and others, running
east and west by Cologne, Juliers, Louvain, Oudenarde, and Courtrai in
Belgium to Cassel, near Dunkirk in France. This boundary line may not
indicate the original seaward extent of the formation, as it may have
stretched still farther north and its present abrupt termination may
only show how far it was cut back at some former period by the denuding
action of the sea.
Even if the imbedded fossil shells of the loess had been lacustrine,
instead of being, as we have seen, terrestrial and amphibious, the vast
height and width of the required barrier would have been fatal to
the theory of a lake: for the loess is met with in great force at
an elevation of no less than 1600 feet above the sea, covering the
Kaiserstuhl, a volcanic mountain which stands in the middle of the great
valley of the Rhine, near Freiburg in Breisgau. The extent to which the
valley has there been the receptacle of fine mud afterwards removed is
most remarkable.
The loess of Belgium was called "Hesbayan mud" in the geological map of
the late M. Dumont, who, I am told, recognised it as being in great
part composed of Alpine mud. M. d'Archiac, when speaking of the loess,
observes that it envelopes Hainault, Brabant, and Limburg like a mantle
everywhere uniform and homogeneous in character, filling up the lower
depressions of the Ardennes and passing thence into the north of France,
though not crossing into England. In France, he adds, it is found on
high plateaus 600 feet above some of the rivers, such as the Marne;
but as we go southwards and eastwards of the basin of the Seine, it
diminishes in quantity, and finally thins out in those directions.*
(* D'Archiac, "Histoire des Progres" volume 2 pages 169,
170.)
It may even be a question whether the "limon des plateaux," or upland
loam of the Somme valley, before alluded to,* may not be a part of the
same formation.
(* Number 4 Figure 7.)
As to the higher and lower level gravels of that valley, which, like
that of the Seine, contain no foreign rocks, we have seen that they are
each of them covered by deposits of loess or inundation-mud belonging
respectively to the periods of the gravels, whereas the upland loam is
of much older date, more widely spread, and occupying positions often
independent of the present lines of drainage. To restore in imagination
the geographical outline of Picardy, to which rivers charged with so
much homogeneous loam and running at such heights may once have belonged
is now impossible.*
(* See above, Chapter 8. )
In the valley of the Rhine, as I before observed, the body of the loess,
instead of having been formed at successively lower and lower levels as
in the case of the basin of the Somme, was deposited in a wide and deep
pre-existing basin, or strath, bounded by lofty mountain chains such
as the Black Forest, Vosges, and Odenwald. In some places the loam
accumulated to such a depth as first to fill the valley and then to
spread over the adjoining table-lands, as in the case of the Lower
Eifel, where it encircled some of the modern volcanic cones of loose
pumice and ashes. In these instances it does not appear to me that the
volcanoes were in eruption during the time of the deposition of the
loess, as some geologists have supposed. The interstratification of loam
and volcanic ejectamenta was probably occasioned by the fluviatile mud
having gradually enveloped the cones of loose scoriae after they were
completely formed. I am the more inclined to embrace this view after
having seen the junction of granite and loess on the steep slopes of
some of the mountains bounding the great plain of the Rhine on its
right bank in the Bergstrasse. Thus between Darmstadt and Heidelberg
perpendicular sections are seen of loess 200 feet thick, at various
heights above the river, some of them at elevations of 800 feet and
upwards. In one of these may be seen, resting on the hill side of
Melibocus in the Odenwald, the usual yellow loam free from pebbles at
its contact with a steep slope of granite, but divided into horizontal
layers for a short distance from the line of junction. In these layers,
which abut against the granite, a mixture of mica and of unrounded
grains of quartz and felspar occur, evidently derived from the
disintegration of the crystalline rock, which must have decomposed in
the atmosphere before the mud had reached this height. Entire shells of
Helix, Pupa, and Succinea, of the usual living species, are embedded in
the granitic mixture. We may therefore be sure that the valley bounded
by steep hills of granite existed before the tranquil accumulation of
this vast body of loess.
During the re-excavation of the basin of the Rhine successive deposits
of loess of newer origin were formed at various heights; and it is often
difficult to distinguish their relative ages, especially as fossils are
often entirely wanting, and the mineral composition of the formation is
so uniform.
The loess in Belgium is variable in thickness, usually ranging from
10 to 30 feet. It caps some of the highest hills or table-land around
Brussels at the height of 300 feet above the sea. In such places it
usually rests on gravel and rarely contains shells, but when they
occur they are of Recent species. I found the Succinea oblonga, before
mentioned, and Helix hispida in the Belgian loess at Neerepen, between
Tongres and Hasselt, where M. Bosquet had previously obtained remains
of an elephant referred to E. primigenius. This pachyderm and Rhinoceros
tichorhinus are cited as characterising the loess in various parts of
the valley of the Rhine. Several perfect skeletons of the marmot have
been disinterred from the loess of Aix-la-Chapelle. But much remains to
be done in determining the species of mammalia of this formation and the
relative altitudes above the valley-plain at which they occur.
If we ascend the basin of the Neckar, we find that it is filled with
loess of great thickness, far above its junction with the Rhine. At
Canstadt near Stuttgart, loess resembling that of the Rhine contains
many fossil bones, especially those of Elephas primigenius, together
with some of Rhinoceros tichorhinus, the species having been lately
determined by Dr. Falconer. At this place the loess is covered by a
thick bed of travertine, used as a building stone, the product of a
mineral spring. In the travertine are many fossil plants, all Recent
except two, an oak and poplar, the leaves of which Professor Heer has
not been able to identify with any known species.
Below the loess of Canstadt, in which bones of the mammoth are so
abundant, is a bed of gravel evidently an old river channel now many
feet above the level of the Neckar, the valley having there been
excavated to some depth below its ancient channel so as to lie in the
underlying red sandstone of Keuper. Although the loess, when traced from
the valley of the Rhine into that of the Neckar, or into any other
of its tributaries, often undergoes some slight alteration in its
character, yet there is so much identity of composition as to suggest
the idea that the mud of the main river passed far up the tributary
valleys, just as that of the Mississippi during floods flows far up the
Ohio, carrying its mud with it into the basin of that river. But
the uniformity of colour and mineral composition does not extend
indefinitely into the higher parts of every basin. In that of the
Neckar, for example, near Tubingen, I found the fluviatile loam or
brick-earth, enclosing the usual Helices and Succineae, together with
the bones of the mammoth, very distinct in colour and composition from
ordinary Rhenish loess, and such as no one could confound with Alpine
mud. It is mottled with red and green, like the New Red Sandstone or
Keuper, from which it has clearly been derived.
Such examples, however, merely show that where a basin is so limited
in size that the detritus is derived chiefly or exclusively from one
formation, the prevailing rock will impart its colour and composition
in a very decided manner to the loam; whereas, in the basin of a great
river which has many tributaries, the loam will consist of a mixture
of almost every variety of rock, and will therefore exhibit an average
result nearly the same in all countries. Thus, the loam which fills to
a great depth the wide valley of the Saone, which is bounded on the west
side by an escarpment of Inferior Oolite, and by the chain of the Jura
on the east, is very like the loess found in the continuation of the
same great basin after the junction of the Rhone, by which a large
supply of Alpine mud has been added and intermixed.
In the higher parts of the basin of the Danube, loess of the same
character as that of the Rhine, and which I believe to be chiefly of
Alpine origin, attains a far greater elevation above the sea than any
deposits of Rhenish loess; but the loam which, according to M. Stur,
fills valleys on the north slope of the Carpathians almost up to the
watershed between Galicia and Hungary, may be derived from a distinct
source.
OSCILLATIONS OF LEVEL REQUIRED TO EXPLAIN THE ACCUMULATION AND
DENUDATION OF THE LOESS.
A theory, therefore, which attempts to account for the position of the
loess cannot be satisfactory unless it be equally applicable to the
basins of the Rhine and Danube. So far as relates to the source of so
much homogeneous loam, there are many large tributaries of the Danube
which, during the glacial period, may have carried an ample supply
of moraine-mud from the Alps to that river; and in regard to grand
oscillations in the level of the land, it is obvious that the same
movements both downward and upward of the great mountain-chain would
be attended with analogous effects, whether the great rivers flowed
northwards or eastwards. In each case fine loam would be accumulated
during subsidence and removed during the upheaval of the land. Changes,
therefore, of level analogous to those on which we have been led to
speculate when endeavouring to solve the various problems presented by
the glacial phenomena, are equally available to account for the nature
and geological distribution of the loess. But we must suppose that
the amount of depression and re-elevation in the central region was
considerably in excess of that experienced in the lower countries, or
those nearer the sea, and that the rate of subsidence in the latter was
never so considerable as to cause submergence, or the admission of the
sea into the interior of the continent by the valleys of the principal
rivers.
We have already assumed that the Alps were loftier than now, when they
were the source of those gigantic glaciers which reached the flanks of
the Jura. At that time gravel was borne to the greatest distances from
the central mountains through the main valleys, which had a somewhat
steeper slope than now, and the quantity of river-ice must at that time
have aided in the transportation of pebbles and boulders. To this state
of things gradually succeeded another of an opposite character, when the
fall of the rivers from the mountains to the sea became less and less,
while the Alps were slowly sinking, and the first retreat of the great
glaciers was taking place. Suppose the depression to have been at the
rate of 5 feet in a century in the mountains and only as many inches in
the same time nearer the coast, still, in such areas as the eye could
survey at once, comprising a small part only of Switzerland or of the
basin of the Rhine, the movement might appear to be uniform and the
pre-existing valleys and heights might seem to remain relatively to each
other as before.
Such inequality in the rate of rising or sinking, when we contemplate
large continental spaces, is quite consistent with what we know of
the course of nature in our own times as well as at remote geological
epochs. Thus in Sweden, as before stated, the rise of land now in
progress is nearly uniform as we proceed from north to south for
moderate distances; but it greatly diminishes southwards if we compare
areas hundreds of miles apart; so that instead of the land rising about
5 feet in a hundred years as at the North Cape, it becomes less than
the same number of inches at Stockholm, and farther south the land is
stationary, or, if not, seems rather to be descending than ascending.*
(* "Principles of Geology" chapter 30 9th edition page 519
et seq.)
To cite an example of high geological antiquity, M. Hebert has
demonstrated that, during the Oolitic and Cretaceous periods, similar
inequalities in the vertical movements of the earth's crust took place
in Switzerland and France. By his own observations and those of M. Lory
he has proved that the area of the Alps was rising and emerging from
beneath the ocean towards the close of the Oolitic epoch, and was above
water at the commencement of the Cretaceous era; while, on the other
hand, the area of the Jura, about 100 miles to the north, was slowly
sinking at the close of the Oolitic period, and had become submerged at
the commencement of the Cretaceous. Yet these oscillations of level were
accomplished without any perceptible derangement in the strata, which
remained all the while horizontal, so that the Lower Cretaceous or
Neocomian beds were deposited conformably on the Oolitic.*
(* "Bulletin de la Societe Geologique de France" 2 series
volume 16 1859 page 596.)
Taking for granted then that the depression was more rapid in the more
elevated region, the great rivers would lose century after century some
portion of their velocity or carrying power, and would leave behind them
on their alluvial plains more and more of the moraine-mud with which
they were charged, till at length, in the course of thousands or some
tens of thousands of years, a large part of the main valleys would
begin to resemble the plains of Egypt where nothing but mud is deposited
during the flood season. The thickness of loam containing shells of land
and amphibious mollusca might in this way accumulate to any extent, so
that the waters might overflow some of the heights originally bounding
the valley and deposits of "platform mud," as it has been termed in
France, might be extensively formed. At length, whenever a re-elevation
of the Alps at the time of the second extension of the glaciers took
place, there would be renewed denudation and removal of such loess; and
if, as some geologists believe, there has been more than one oscillation
of level in the Alps since the commencement of the glacial period, the
changes would be proportionally more complicated and terraces of gravel
covered with loess might be formed at different heights and at different
periods.
HIMALAYAN MUD OF THE GANGES COMPARED TO EUROPEAN LOESS.
Some of the revolutions in physical geography above suggested for the
continent of Europe during the Pleistocene epoch, may have had their
counterparts in India in the Recent Period. The vast plains of Bengal
are overspread with Himalayan mud, which as we ascend the Ganges extends
inland for 1200 miles from the sea, continuing very homogeneous on the
whole, though becoming more sandy as it nears the hills. They who sail
down the river during a season of inundation see nothing but a sheet of
water in every direction, except here and there where the tops of trees
emerge above its level. To what depth the mud extends is not known, but
it resembles the loess in being generally devoid of stratification, and
of shells, though containing occasionally land shells in abundance, as
well as calcareous concretions, called kunkur, which may be compared to
the nodules of carbonate of lime sometimes observed to form layers in
the Rhenish loess. I am told by Colonel Strachey and Dr. Hooker that
above Calcutta, in the Hooghly, when the flood subsides, the Gangetic
mud may be seen in river cliffs 80 feet high, in which they were unable
to detect organic remains, a remark which I found to hold equally in
regard to the Recent mud of the Mississippi.
Dr. Wallich, while confirming these observations, informs me that at
certain points in Bengal, farther inland, he met with land-shells in the
banks of the great river. Borings have been made at Calcutta, beginning
not many feet above the sea-level, to the depth of 300 and 400 feet; and
wherever organic remains were found in the strata pierced through they
were of a fluviatile or terrestrial character, implying that during a
long and gradual subsidence of the country the sediment thrown down
by the Ganges and Brahmaputra had accumulated at a sufficient rate to
prevent the sea from invading that region.
At the bottom of the borings, after passing through much fine loam, beds
of pebbles, sand, and boulders were reached, such as might belong to an
ancient river channel; and the bones of a crocodile and the shell of
a freshwater tortoise were met with at the depth of 400 feet from the
surface. No pebbles are now brought down within a great distance of
this point, so that the country must once have had a totally different
character and may have had its valleys, hills, and rivers, before all
was reduced to one common level by the accumulation upon it of fine
Himalayan mud. If the latter were removed during a gradual re-elevation
of the country, many old hydrographical basins might reappear, and
portions of the loam might alone remain in terraces on the flanks of
hills, or on platforms, attesting the vast extent in ancient times
of the muddy envelope. A similar succession of events has, in all
likelihood, occurred in Europe during the deposition and denudation of
the loess of the Pleistocene period, which, as we have seen in a former
chapter, was long enough to allow of the gradual development of almost
any amount of such physical changes.
HUMAN REMAINS IN THE LOESS NEAR STRASBURG.
M. Ami Boue, well known by his numerous works on geology and a
well-practised observer in every branch of the science, disinterred in
the year 1823 with his own hands many bones of a human skeleton from
ancient undisturbed loess at Lahr, nearly opposite Strasburg, on the
right side of the great valley of the Rhine. No skull was detected, but
the tibia, fibula, and several other bones were obtained in a good state
of preservation and shown at the time to Cuvier, who pronounced them to
be human.
HUMAN REMAINS IN LOESS NEAR MAESTRICHT.
The banks of the Meuse at Maestricht, like those of the Rhine at Bonn
and Cologne, are slightly elevated above the level of the alluvial
plain. On the right bank of the Meuse, opposite Maestricht, the
difference of level is so marked that a bridge with many arches has been
constructed to keep up, during the flood season, a communication between
the higher parts of the alluvial plain and the hills or bluffs which
bound it. This plain is composed of modern loess, undistinguishable in
mineral character from that of higher antiquity, before alluded to,
and entirely without signs of successive deposition and devoid
of terrestrial or fluviatile shells. It is extensively worked for
brick-earth to the depth of about 8 feet. The bluffs before alluded to
often consist of a terrace of gravel, from 30 to 40 feet in thickness,
covered by an older loess, which is continuous as we ascend the valley
to Liege. In the suburbs of that city patches of loess are seen at the
height of 200 feet above the level of the Meuse. The table-land in that
region, composed of Carboniferous and Devonian rocks, is about 450 feet
high, and is not overspread with loess.
A terrace of gravel covered with loess has been mentioned as existing
on the right bank of the Meuse at Maestricht. Answering to it another
is also seen on the left bank below that city, and a promontory of
it projecting into the alluvial plain of the Meuse and approaching
to within a hundred yards of the river, was cut through during the
excavation of a canal running from Maestricht to Hocht, between the
years 1815 and 1823. This section occurs at the village of Smeermass,
and is about 60 feet deep, the lower 40 feet consisting of stratified
gravel and the upper of 20 feet of loess. The number of molars, tusks,
and bones (probably parts of entire skeletons) of elephants obtained
during these diggings, was extraordinary. Not a few of them are still
preserved in the museums of Maestricht and Leyden, together with some
horns of deer, bones of the ox-tribe and other mammalia, and a human
lower jaw, with teeth. According to Professor Crahay, who published an
account of it at the time, this jaw, which is now preserved at Leyden,
was found at the depth of 19 feet from the surface, where the loess
joins the underlying gravel, in a stratum of sandy loam resting on
gravel and overlaid by some pebbly and sandy beds. The stratum is said
to have been intact and undisturbed, but the human jaw was isolated,
the nearest tusk of an elephant being six yards removed from it in
horizontal distance.
Most of the other mammalian bones were found; like these human remains,
in or near the gravel, but some of the tusks and teeth of elephants were
met with much nearer the surface. I visited the site of these fossils in
1860 in company with M. van Binkhorst, and we found the description of
the ground, published by the late Professor Crahay of Louvain, to be
very correct.*
(* M. van Binkhorst has shown me the original manuscript
read to the Maestricht Athenaeum in 1823. The memoir was
published in 1836 in the "Bulletin de l'Academie Royale de
Belgique" volume 3 page 43.)
The projecting portion of the terrace, which was cut through in making
the canal, is called the hill of Caberg, which is flat-topped, 60 feet
high, and has a steep slope on both sides towards the alluvial plain.
M. van Binkhorst (who is the author of some valuable works on the
palaeontology of the Maestricht Chalk) has recently visited Leyden, and
ascertained that the human fossil above mentioned is still entire in the
museum of the University. Although we had no opportunity of verifying
the authenticity of Professor Crahay's statements, we could see no
reason for suspecting the human jaw to belong to a different geological
period from that of the extinct elephant. If this were granted, it might
have no claims to a higher antiquity than the human remains which Dr.
Schmerling disentombed from the Belgian caverns; but the fact of their
occurring in a Pleistocene alluvial deposit in the open plains, would be
one of the first examples of such a phenomenon. The top of the hill of
Caberg is not so high above the Meuse as is the terrace of St. Acheul
with its flint implements above the Somme, but at St. Acheul no human
bones have yet been detected.
In the museum at Maestricht are preserved a human frontal and a pelvic
bone, stained of a dark peaty colour; the frontal very remarkable
for its lowness and the prominence of the superciliary ridges, which
resemble those of the Borreby skull, Figure 5. These remains may be the
same as those alluded to by Professor Crahay in his memoir, where he
says that in a black deposit in the suburbs of Hocht were found leaves,
nuts, and freshwater shells in a very perfect state, and a human skull
of a dark colour. They were of an age long posterior to that of the
loess containing the bones of elephants and in which the human jaw now
at Leyden is said to have been embedded.