once develope, are set the task of carrying back to the sea all that
stands above it. According to the amount of this alloted work that
streams have accomplished, they may be said to be young, mature or
aged; and if, their task once nearly completed, another uplift raise
more material to be carried off, they may be said to be revived. These
terms apply equally to the land-surface, and each period of development
is characterized by certain topographic forms.
In youth simple stream systems sunk in steep walled cañons are
separated by broad areas of surface incompletely drained. In maturity
complex stream systems extend branches up to every part of the surface;
steep slopes, sharp divides, pyramidal peaks express the rapidity with
which every portion of the surface is attacked.
In old age the gently rolling surface is traversed by many quiet
flowing streams; the heights are gone, the profiles are rounded, the
contours subdued. In the first emergence from the sea the courses of
streams are determined by accidents of slope, it may be by folding of
the rising surface into troughs and arches. During maturity the process
of retrogressive erosion, by which a stream cuts back into the
watershed of a less powerful opponent stream, adjusts the channels to
the outcrops of soft rocks and leaves the harder strata as eminences.
In old age this process of differential degradation is complete and
only the hardest rocks maintain a slight relief.
Suppose that an aged surface of this character be revived: the rivers
hitherto flowing quietly in broad plains will find their fall increased
in their lower courses; their channels in soft rock will rapidly become
cañons, and the revived phase will retreat up stream in the same manner
that the cañons of youth extended back into the first uplifted mass. If
the area of soft rocks be bounded by a considerable mass of very hard
rocks, it is conceivable that a second phase of age, a base level,
might creep over the valley while yet the summits of the first old age
remained unattacked, and should perchance revival succeed revival the
record of the last uplift might be read in sharp cut channels of the
great rivers, while the forms of each preceding phase led like steps to
the still surviving domes of that earliest old age.
Is there aught in these speculations to fit our facts? I think there
is. We have seen that our mountains and valleys are the result of
differential degradation, and that this is not only broadly true but
true in detail also. This is evidence that streams have been long at
work adjusting their channels, they have passed through the period of
maturity.
We have climbed to the summits of the Unakas and found them composed of
rocks as hard as those from which the pinnacle of the Matterhorn is
chiseled; but we see them gently sloping, as a plain. These summits are
very, very old.
We have recognized that dissected plain, the level of the Asheville
amphitheatre, now 2,400 feet above the sea; it was a surface produced
by subaerial erosion, and as such it is evidence of the fact that the
French Broad River, and such of its tributaries as drain this area, at
one time completed their work upon it, reached a base level. That they
should have accomplished this the level of discharge of the sculpturing
streams must have been constant during a long period, a condition which
implies either that the fall from the Asheville plain to the ocean was
then much less than it now is, or that through local causes the French
Broad was held by a natural dam, where it cuts the Unaka chain.
If we should find that other rivers of this region have carved the
forms of age upon the surfaces of their intermontane valleys, and there
is now some evidence of this kind at hand, then we must appeal to the
more general cause of base-levelling and accept the conclusion that the
land stood lower in relation to the ocean than it now does.
Furthermore, we have traversed the ravines which the streams have cut
in this ancient plain and we may note on the accompanying atlas sheet
that the branches extend back into every part of it; the ravines
themselves prove that the level of discharge has been lowered, the
streams have been revived; and the wide ramification of the brooks is
the characteristic of approaching maturity.
We have also glanced at the topography of the valley and have found the
rivers flowing in deep-cut simple channels which are young, and the
smaller streams working on an undulating surface that is very sensitive
to processes of degradation.
The minor stream systems are very intricate and apparently mature, but
they have not yet destroyed the evidence of a general level to which
the whole limestone area was once reduced, but which now is represented
by many elevations that approach 1,600 feet above the sea. Here then in
the valley are young river channels, mature stream systems and faint
traces of an earlier base level, all of them more recent than the
Asheville level, which is in turn less ancient than the dome-like
summits of the Unakas.
What history can we read in these suggestive topographic forms and
their relations?
The first step in the evolution of a continent is its elevation above
the sea. The geologist tells us that the earliest uplift of the
Appalachian region after the close of the Carboniferous period was
preceded or accompanied by a folding of the earth's crust into
mountainous wave-like arches; upon these erosion at once began and
these formed our first mountains. Where they were highest the geologist
may infer from geologic structure and the outcrops of the oldest rocks;
but the facts for that inference are not yet all gathered and it can
only be said that the heights of that ancient topography were probably
as great over the valley of Tennessee as over the Unaka chain. The
positions of rivers were determined by the relations of the arches to
each other and, as they were in a general way parallel, extending from
northeast to southwest, we know that the rivers too had
northeast-southwest courses. From that first drainage system the
Tennessee river, as far down as Chattanooga, is directly descended, and
when the geologic structure of North Carolina and East Tennessee is
known, we may be able to trace the steps of adjustment by which the
many waters have been concentrated to form that great river. At present
we cannot sketch the details, but we know that it was a long process
and that it was accompanied by a change in the _raison d'être_ of the
mountain ranges. The first mountains were high because they had been
relatively raised; they gave place to hills that survived because they
had not been worn down. A topography of differential uplift gave place
to one of differential degradation. And to the latter the dome-like
"balds" of the Unakas belong. Those massive summits of granite,
quartzite and conglomerate are not now cut by running waters; they are
covered with a mantel of residual soil, the product of excessively slow
disintegration, and they are the remnants of a surface all of which has
yielded to degradation, save them. In time the streams will cut back
and carve jagged peaks from their masses, but standing on their heights
my thought has turned to the condition they represent--the condition
that is past. And thus in thought I have looked from the Big Bald out
on a gently sloping plain which covered the many domes of nearly equal
height and stretched away to merge on the horizon in the level of the
sea. That, I conceive, was the first base level plain of which we have
any evidence in the Appalachians and from that plain our present
valleys have been eroded. The continental elevation must then have been
3,000 or 4,000 feet less than it is now, and the highest hills were
probably not more than 2,500 feet above the sea. This was perhaps a
period of constant relation between sea and land, but it was succeeded
by one during which the land slowly rose. The rivers, which had
probably assumed nearly their present courses, were revived; the
important channels soon sank in cañons, the tributaries leaped in
rapids and cut back into the old base level. The region continued to
rise during a period long enough to produce the essential features of
the mountain ranges of to-day; then it stood still in relation to the
sea or perhaps subsided somewhat, and the French Broad and probably
other rivers made record of the pause in plains like that about
Asheville. Again the land rose slowly; again it paused, and rivers,
working always from their mouths backward, carved a base-level in the
limestones of the great valley; but before that level could extend up
through the gorges in the Unakas, the continent was raised to its
present elevation, the streams responded to the increased fall given
them and the rivers in the valley began to cut their still incomplete
cañons.
Are we not led step by step from these latest sharply cut channels up
stream through the chapters of erosion to the still surviving domes of
an early old age? Let us sum up the history we have traced. There is
reason to believe that:
1st. The consequent topography of the earliest Appalachian uplift was
entirely removed during a prolonged period of erosion and was replaced
by a relief of differential degradation.
2d. The balds of the Unakas represent the heights of that first-known
approach to a base-level.
3d. The topography of the region has been revived by a general, though
not necessarily uniform, uplift of 3,000 feet or more, divided by two
intervals of rest; during the first of these the Asheville base-level
was formed; during the second, the valley alone was reduced.
4th. The latest movement of the uplift has been, geologically speaking,
quite recent, and the revived streams have accomplished but a small
part of their new task.
These conclusions are reached on the observation of a single class of
facts in one district; they must be compared with the record of
continental oscillation on the sea coasts, in the deposits of the
coastal plain, and in the topography of other districts.
The history of the Appalachians is written in every river system and on
every mountain range, but in characters determined for each locality by
the local conditions. Only when the knowledge, to which every tourist
may contribute, is extended over the entire region shall we know
conclusively the whole story.
A TRIP TO PANAMA AND DARIEN.
BY RICHARD U. GOODE.
The Government of the United States of Colombia in its act of
Concession to the Panama Canal Company provided that it should give to
the latter _"gratuitement et avec toutes les mines qu'ils pourront
contenir"_ 500,000 hectares of land.
Some of the conditions attached to this grant were, that the land
should be selected within certain limits and surveyed by the Canal
Company; that a topographical map should be made of the areas surveyed
and that an amount equal to that surveyed for the canal should also be
surveyed for the benefit of the Colombian Government. It was also
further agreed that it would not be necessary to complete the canal
before any of the land should be granted, but that it would be given at
different times in amounts proportional to the amount of work
accomplished.
Thus in 1887, the Government agreed to consider that one-half of the
work on the canal had been finished and that the canal was consequently
entitled to 250,000 hectares of land, upon the completion of the
necessary surveys, etc.
The land was eventually chosen partly in Darien and partly in Chiriqui
as follows:
In Darien three lots, one between the Paya and Mangle rivers, one
between the Maria and Pirri rivers, the two amounting to 100,000
hectares, and one lot of 25,000 hectares between the Yape and Pucro
rivers.
In Chiriqui, which is a Province of Panama just east of Costa Rica, two
lots were chosen amounting to 125,000 hectares, one between the Sigsola
and Rabalo rivers, and the other between the Catabella and San Pedro
rivers.
The Canal Company wanted the title to the land in order that it might
be used as collateral security in bolstering up the finances of the
corporation, and the Colombian Government was doubtless very willing to
let the Canal Company have this amount or as much more as was wanted,
both parties being equally aware of the valueless character of the land
for any practical purposes.
My services were engaged in 1888 in connection with the astronomical
work incident to the survey of these grants and it was intended that I
should visit both Darien and Chiriqui, but the contract term expired
about the time of the completion of the work in Darien, which was taken
up first, and it was deemed prudent for various reasons, the chief of
them being the unhealthiness of the locality at that season of the
year, about the middle of April, not to remain longer on the Isthmus.
If it had been possible to work as expeditiously as in this country
there would have been ample time to have completed the necessary
astronomical work for both surveys, and without understanding men and
methods peculiar to a tropical country I started out with this
expectation, but soon found out that any efforts looking towards
expediting any particular matter were not only useless but were
detrimentally reactive upon the person putting forward such efforts.
Thus it was nearly the first of March before I reached Darien, having
sailed from New York a month previously. Passage was had from Panama to
Darien in a steamer chartered for the purpose. Sailing across the Bay
of Panama and entering the Tuyra River at Boca Chica, we ascended the
river as far as the village Real de St. Marie. At this point the
steamer was abandoned and further transportation was had in canoes.
Darien is a province of the State of Panama and its boundaries as given
by Lieut. Sullivan in his comprehensive work on "Problem of
Interoceanic Communication," are as follows: "The Atlantic coast line
is included between Point San Blas and Cape Tiburon; that of the
Pacific extends from the mouth of the Bayano to Point Ardita. The
eastern boundary is determined by the main Cordillera in its sweep
across the Isthmus from a position of close proximity to the Pacific,
near Point Ardita, to a similar position near Tiburon, on the Atlantic.
The valleys of the Mandinga and Mamoni-Bayano determine its western
limit."
The Darien hills as seen from the Atlantic side present to the view an
apparently solid ridge of mountains, although there are in reality many
low passes which are concealed by projecting spurs.
The dividing ridge hugs close to the Atlantic, and the rivers, of which
there are a great many on this side, plunge abruptly to the sea. On the
Pacific side the rivers have a much longer distance to flow before
reaching the sea, and the territory bordering on the ocean is low and
swampy. The tidal limit of the Tuyra River is nearly fifty miles from
its mouth, and on this river and many of its tributaries one can travel
many miles inland before ground sufficiently solid to land upon can be
found. The vegetation within this low lying area is thick and closely
matted together, and this fact taken in connection with the swampy
character of the ground, makes travel on foot through any portion of it
exceedingly difficult. Therefore the various rivers, which form a very
complex system and penetrate everywhere are the natural highways of the
country. The chief rivers on the Pacific side are the Tuyra and Boyano
with their numerous tributaries and on the Atlantic watershed is the
Atrato.
A peculiarity noticed at Real de St. Marie, which is at the junction of
the Pyrrhi and Tuyra rivers and at which point the tide has a rise and
fall of twelve or fifteen feet, was that at low tide it was impossible
to enter the mouth of the Pyrrhi with a boat, while five or six miles
up the stream there was always a good supply of flowing water and at
double that distance it became a mountain torrent.
Outside of the swampy area the character of the country is rough and
mountainous. The valleys are narrow and the ridges exceedingly sharp,
the natural result of a great rain fall. The hills are able to resist
the continued wasting effect of the vast volumes of descending water
only by their thick mantle of accumulated vegetation, and were it not
for this protection the many months of continuous annual rain would
long ago have produced a leveling effect that would have made
unnecessary the various attempts of man to pierce the Isthmian
mountains and form an artificial strait.
The ridges are sometimes level for a short distance, but are generally
broken and are made up of a succession of well rounded peaks. These
peaks are always completely covered with trees and from the top of the
sharpest of them it is impossible to get a view of the surrounding
country. The highest point climbed was about 2,000 feet above sea level
and the highest peak in Darien is Mt. Pyrrhi which is between three and
four thousand.
Darien has been the scene of a great deal of surveying and exploration
from the time that Columbus, in 1503, coasted along its shores, hoping
to find a strait connecting the two oceans, up to the present time.
Balboa, in 1510, discovered the Pacific by crossing the Darien
mountains from Caledonia Bay. This discovery taken in connection with
the broad indentations of the land noted by Columbus, led the old world
to believe in the existence of a strait, and the entire coast on each
side of the new world was diligently searched. The Cabots, Ponce de
Leon and Cortez interested themselves in this search and it was not
until about 1532 that all expectations of finding the strait were
abandoned. The idea of a direct natural communication between the
oceans being thus dispelled, the question of an artificial junction
arose, and in 1551 a Spanish historian recommended to Philip II. of
Spain the desirability of an attempt to join the oceans by identically
the same routes to which the attention of the whole civilized portion
of the world is now being drawn, that is, Tehauntepec, Nicaragua and
Panama. From this time up to the commencement of the work of the
Isthmian expeditions sent out by the United States, and which lasted
from 1870 to 1875, but little geographical knowledge relative to Darien
was obtained. The United States expeditions undoubtedly did a great
amount of valuable exploration and surveying, and while the names of
Strain, Truxton, Selfridge and Lull will always be held in high esteem
for what they accomplished in this direction, still it is to be
regretted that with all the resources at their command they did not
make a complete map of the country. And just here I want to bring
forward the suggestion that all that has been accomplished and more,
could have been accomplished if the various explorers had known, or
practically utilized, a fact that my own experience and that of other
topographers, in this country and Darien, has impressed upon me; and
that is, that it is easier in a rough and mountainous country to travel
on the ridge than in the valley. In Darien they were looking for a low
pass in the Cordillera and this was what should have first been sought,
directly. Having found the low passes the valleys of the streams
draining therefrom could have then been examined, and thus all
necessary information could have been obtained and the subject
exhausted. The plan followed by the Isthmian expeditions was to ascend
a stream with the hope of finding a suitable pass. The pass might be
found or it might not, and if not, so much labor as far as the direct
solution of the problem was concerned was lost. A pass of low altitude
was of primary importance and should have been sought for in an
exhaustive way.
Humboldt said in substance, "Do not waste your time in running
experimental lines across. Send out a party fully equipped, which
keeping down the dividing ridge the whole length of the Isthmus, by
this means can obtain a complete knowledge of the hypsometrical and
geological conditions of the dam that obstructs the travel and commerce
of the world." But strange to say this plan suggested by such an
eminent authority as Humboldt and so strongly recommended by common
sense, has never been followed, and to-day after all the money that has
been spent and the lives lost in explorations in Darien, there is not
sufficient data collected to prove conclusively that there does not now
exist some route for an interoceanic canal that possesses merits
superior to any at present known. It is true the dividing ridge would
be difficult to follow on account of the great number of confusing
spurs, but I think I am safe in saying that starting from the summit of
the main ridge at Culebra pass on the Isthmus of Panama, the dividing
ridge extending to the pass at the head waters of the Atrato could be
exhaustively followed and studied with as much facility as could either
the Tuyra or Atrato rivers, embracing with each their respective
tributaries.
I traveled on some of the high dividing ridges in Darien, and did not
find that progress was at all difficult, and especially noted the fact
of the absence of tangled undergrowth and matted vines which is so
characteristic of the Darien forests generally.
Now a few words about the inhabitants of Panama and Darien, and in
referring to these I mean the native inhabitants and not the
indiscriminate gathering of all nationalities that were attracted by
the Panama Canal.
In Central and South America, as in North America, the aboriginal
inhabitant was the Indian. When the Spaniards first attempted to
colonize Darien they were met and resisted by the native Indian just as
our forefathers were in Virginia and Massachusetts, and as with us so
in Panama and Darien the Indians have been driven back by degrees from
the shores of both oceans until now they are found only in the far
interior.
They resemble our Indians in appearance, but are smaller. They are
averse to manual labor and live almost entirely by hunting and fishing,
although they sometimes have small plantations of plantains, bananas,
oranges and lemons. The Spaniards in settling in the new country
brought very few women with them and the Colombian of to-day is the
result of the admixture of the Indian and Spanish blood, and has many
of the characteristics of each race. In addition to the Indian and
Colombian there are in Panama and Darien a comparatively large number
of negroes, who were originally imported as slaves by the early
Spaniards, and who now constitute by far the larger portion of the
inhabitants of Darien, being found usually in villages along the
valleys of the larger streams. In contrast to the Colombian and Indian
they are large in stature and make excellent laborers.
The principal villages in Darien, as Yovisa, Pinagana and Real de St.
Marie, are inhabited exclusively by the negroes, with the exception of
a Spanish judge in each, who exercises great authority. Besides being a
judge in civil and criminal cases, he practically controls everything
in his particular village, as all contracts for labor are negotiated
with him and settlement for services made through him.
Upon reaching Darien the first work assigned me was the survey and
exploration of the Pyrrhi river. This survey was made for two purposes:
primarily, to determine if any of the country bordering upon it was of
a sufficiently desirable character to include it within the grant, and
secondly, to secure data for the general topographical map. My
instructions were to proceed as far south as latitude 7° 30'. The
ascent of the river was made in canoes until the frequency of rapids
made it necessary to abandon them, and then the journey was continued
on foot, generally wading in the middle of the stream, as the
undergrowth was too thick to admit of progress along the banks.
Sometimes the water was very shallow; at other times, where it had been
backed up by dams of porphyritic rock, it reached above the waist, and
near the end of the journey where the river ran between vertical walls
of great height it was necessary to swim in order to get beyond this
cañon.
The survey of this river was satisfactorily accomplished in about a
week. The method adopted for the survey was to take compass bearings
and to estimate distances. These courses and distances were plotted as
they were taken and thus the topographical and other features could be
readily sketched in connection with them. To check and control this
work, observations were taken every day at noon with a sextant, on the
sun, for latitude and time, and at night circum-meridian altitudes of
stars were obtained when possible.