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northwest coasts large bays are not prominent and are rather
irregular in their shape and alignment.

Among the large peninsulas of the west coast those of Port
au Choix, Cow Head, and Port au Port are the most irregular,
the last having a long northern prolongation which finds its
continuation in the submerged Long Ledge, a few miles beyond.
Each of these headlands is connected with the mainland by a
low and narrow neck of accumulated sands and nmds which
an elevation of the sea-level of but about 25 feet would sub-
merge, converting the peninsula into an island.

Tlie more important bays of the west and northwest coasts
are Bonne, St. George, and St. Barbe Bays, the Bay of Islands,
and the double reentrant made by Port Sandei-s and Hawke
Harbor. With the exception of St. Greorge Bay, each of these
extends far into the land with deep waters almost to the head.
The Bay of Islands and Bonne Bay branch just a short dis-
tance from the sea, and then each branch extends back into
the land for many miles. Across the mouth of the former
there is a string of high islands which are formed of the same
kind of rock as exists on each side of the bay. Port au Choix
Bay may also be mentioned ; not because of its size, but by
reason of its-narrow entrance and the enormous depth of water
within a stone's throw of the shore.

Islands. — Along the coasts of Newfoundland there are many
islands, of which only those of the west coast have been seen
and to which the remarks that follow alone apply. Those
about the western extremity of Belle Isle Strait are very low
and of most extravagant shapes. In the broad indentation
extending from St. Barbe Bay to Port au Choix there is a suc-
cession of low islands and long peninsulas, one of which. Point
Ferolle, divides the indentation into almost equal parts. The
islands of the northern part are separated from the mainland,
here low, by very shallow water. The southern embayment
contains sixteen islands, of which the largest is St. John.
Deep water lies between this group and the mainland, here
formed of the St. John Mountains, an outlier of the Long
Range. South from Port au Choix islands are uncommon, if
those at the mouth of the Bay of Islands be excepted.

Off setting of the west coast. — The west coast of Newfound-
land shows at four localities, — Point Ferolle, Port au Choix,
Table Point, and St. George Bay, — rather striking offsettings,
or inland sags of the coast. At each of these places the shore
makes a very abrupt bend in an easterly direction, southward
from which it continues parallel to the original coastal line.
The three northern offsets are parallel to each other, with a
southeasterly trend ; but the St. George Bay offset trends almost
due east and finds its continuation inland in the valley of St.



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14 W. II. Twenhofel — Physiography of Newfoundland,

George River, an almost straight line. The Table Point sag
has a thousand-foot fanlt at its back, Logan has described a fault
at the back of the Port au Choix oflEset, while numerous faults
are known about St. George Bay, at the back of which is the
great displacement described by Murray. Of Point Ferolle
nothing is known.

EviDKNCE OF Uplift.

In shaping the surface of Newfoundland, relative elevation
has been an extremely important factor, and the evidence for
this is given in the paragraphs that follow.

Youthful aspect of the streams. — The rivers of the west
coast present a rather striking aspect of youth. Except where
the mouths are drowned, all that were seen consist in their
lower courses of a series of rapids and falls and flow as a rule
in steep-walled gorges. Inland the waters move more slowly,
but the numerous lakes with rapid w^aters between, as described
by Murray and Howley, prove the immaturity of drainage.

Tei^aces, — From tlie Straits of Belle Isle to the southwest
corner of the island, systems of terraces rise like giant staircases

Fig. 6.



Fig. 6. Elevated terraces cut in igDeons rock at Beverly Head, north of
the Bay of Islands. The nppermo&t is abont 400 feet, the lowest abont 20
feet, the very marked one about 75 feet. Photograph by Charles Schuchert.

from the sea. The lowest of these is less than a dozen feet
above high water, the highest observed rises above 400 feet.
Finely pi-eserved examples of a 25-foot terrace, backed by a 25-
foot cliflE, exist on the islands north of the Port au Choix penin-
sula, on the peninsula itself, and at numerous places south
therefrom to tne Bay of Islands, particularly in the islands at



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W. H. Twenlwfd — Physiography of Newfoundland. 15

the mouth. The flat-topped " barrens " of the foreland rising
to elevations of about 75 feet or less, are remnants of terraces
that are devoid of trees by reason of their 8wan;ipiness. Around
Alall Bay south of Hawke Harbor, three beautifully preserved
terraces occur at elevations of about 15, 25, and 40 feet, while
still higher may be seen remnants of others,, and at Romaine
River, near Port au Port, there are five, the .highest about 70
feet above the sea.

In the interior, terraces exist around Grand and Deer Lakes,
there being at least three at the former at about 5, 15, and 60
feet above lake level, which is 255 feet above the sea ; and in
the Humber gorge there are also at least three.* There seems
no reason for doubting that these inland terraces can be readily
correlated with those of the shore.

Barrier heaches, — At several places barriers extend along
the sides of shore slopes like windrows of hay in a meadow.
Two places in particular where such are rather marked are
Current Island, south of St. Barbe Bay, where there are eight,
the highest being between 20 and 25 feet above sea-level, and
each elevated about 2 to 3 feet above the other ; and at Trap-
per Cove, south of Hawke Harbor, where there are six, with
the highest about 20 feet above sea-level, with about 3 feet ver-
tically between one and the next above. These barriers are
bare of vegetation and are composed of fresh rock derived from
the limestone of the coast, and have, moreover, been there a
number of years, appearing to have been formed by successive
relative elevations and not by a succession of storms, each of
less magnitude than the preceding, as at the latter point they
are in a protected place and in the former on the land side of
the island.

Delta deposits. — At the mouth of almost every stream on the
west coast there is aflat-topped alluvial deposit with the upper sur-
face now standing at an elevation of 60 to 75 feet. The depos-
its consist of coarse and fine alluvium, the particles rounded, and
derived in most cases from the neighboring elevations. They
cannot be interpreted as other than delta deposits formed at a
time when the strand-line stood relatively higher by at least 60
feet. At many places on each side of the delta flat a terrace
continues the level, winding in and out of the reentrants of the
coast (see view 4).

Marine shells. — My a arenaria was observed in clays and
sand at two localities on the west coast of Newfoundland, — the
modern seacliflE on the west side of Port Sanders and in the
cliffs of glacial material five or six miles south of Hawke Har-
bor, being in each case but a few feet above high-tide level.
Rock surfaces riddled by lithodomous shells exist at many
* Schnchert, Note book, September 4, 1910.



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16 W. H, Twenhofel — Physiography of Nexofoundland,

points on the west coast of Newfoundland to elevations as great
as 75 feet, and at Bell Burns Cove, just south of Table Point,
Mr. Thomas House stated that in digging a well* on the edge
of the raarsh, about one-half mile from the shore and 40-50
feet above high tide, he had passed through a bed of "clams.''

Fig. 7.



Fig. 7. Trout River, south of Bonne Bay. The 60-75 foot elevated beach
and delta are shown with the elevated peneplain in the background. The
houses stand on the lowest terrace. Photograph by Charles Schuchert.

Constructions, — No evidence based on human constructions
was seen, nor did anyone appear to have any information lead-
ing to any conclusions. It is, however, stated by Dalyf that
along the coasts of Labrador and Newfoundland the fish stages
have had to be lengthened a^in and again, while among the
shoals new passages have had to be sought due to the shoaling
of the old.

Evidence op Submebgence.

Drowned goraes, — St. Barbe Bay, Port Sanders, Bonne Bay,
and the Bay oi Islands are drowned gorges, the submerged
lower courses of once swiftly flowing mountain streams. Each
shows all the characters of a river system, — St. Barbe with three
main branches and some smaller ones. Port Sanders with two
main arms and each with smaller ones. Bonne Bay with three
branching arms, and the Bay of Islands with an equal number,
each of which fingers out near its head. Each branch of an

* The inhabitants of some of the villages on the west coast migrate annu-
ally to the woods on the edge of the marsh fronting the Long Range in order
to escape the winds, hence the well.

t Daly, Bull. Mus. Comp. Zool., xxxviii, p. 261, 1902.



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W. S. Twenhofel — Physiography of Newfoundland, IT

arm receives its tributary, a remnant of a dismembered river
system. At Bonne Bay and the Bay of Islands the mountains
tower over the water with elevations of 2000 feet a mile from
the shore, and cliffs rise from the water's edge to nearly a
thousand feet, while in the bays the slope descends precipi-
tously from a shallow shelf, where ships may anchor, to deptns
greater than 700 feet.* The other bays do not have such
igh margins, though almost equally precipitous, nor do they
descend so deep; but depths of 500 feet are not exceptional.

Low islands, — Attention has been called to the numerous
low islands on that portion of the coast extending from Belle
Isle Strait to Port au Choix. North of St. Barbe Bay these are
quite low, many barely rising above the surface of the water,
yet with relatively deep water on their inland sides. South
from St. Barbe Bay the islands are a little higher and the coast
line of the north, if projected south, would rest on the surface of
the outer islands and again touch the mainland at Point Eich,
the outer extremity of the Port au Choix peninsula. The fore-
land almost ceases to exist on this portion of the coast, but in
its place appear numerous islands with passages between them
and the mainland of suiEcient depth to float large steamers.
The islands are thought to represent the submerged foreland.
Between the Bay of Islands and Port au Port the general
line of the coast is continued by the submerged Long Ledge
and Long Point and the outer margin of the peninsula. The
enclosed waters are, in general, quite shallow. An exception
is a long narrow trough of 20 fathoms depth that very closely
follows the main shore. This bay with its low islands and sub-
merged ledges is also thought to be a part of the submerged
foreland.

Suhmerqed folds off the Avalon peninsula. — That the east
side of Newfoundland is in a drowned condition appears
equally certain. Nearly every river in its lower course enters
in a deep bay and the headlands rise precipitously from the
water's edge. The parallelism of the peninsulas and bays on
this portion of the coast is one of its remarkable features ; but
equally striking is the submerged topography immediate to the
shore with peninsulas essentially similar to those above the
water and bays little different from those of the present coast.

Effects of Glaciation. ^

Along the west coasts erratics are quite common and deposits ^
of till and bowlders exist at several places in considerable thick-

* A part of this depth maj be due to glacial overdeepening. How nmoh,
however, there are no means of determining, but it is to be noted that the
water is more shallow at the entrances than in the interior of the bays. The
channels, however, could readily have been filled by the currents that drift
along the coast.

Am. Jour. Sci.— Fourth Skribs, Vol. XXXIII, No. 198.— January, 1912.
2



\^



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18 W. H, Twenhofd — Physiography of Newfoundland.

nesses, notably in the cliffs about ten miles south of Hawke
Harbor. In the interior, along the line of the railroad, glacial
debris appears to be more abundant, the mountain slopes being
cloaked with material, morainic in character.*

Striae were seen at numerous localities, generally with a direc-
tion closely approximating the trend of the valleys of the place
in question. Their presence was noted on top of Table Moun-
tain, at Bonne Bay, in the elevated valleys, and numerous
places on the foreland.

The upper system of valleys in the Long Range are decid-
edly U-shaped while the flared-out heads of some of them
strongly resemble the descriptions given of cirques, which resem-
blance is intensified by the lakes and ponds found in these val-
leys and held in rock basins. Nearly every one of the valleys
shows by the polished rock surfaces that at one time it was
filled with the ice, and their precipitous margins are no doubt,
in part, due to its work. The surface at many points has a
rounded aspect, seen to good advantage near the mouth of the
Bay of Islands in the foothills of Mount Blomidon« and to the
work of ice may perhaps be ascribed, in part, the gouging out
of the deep bays existing around the entire coast although those
of the west side are decidedly canyon-like.

That glaciers covered the western side of the island to the
highest summits is certain and the same was probably true in
respect to the other parts of Newfoundland. The direction of
the striae on the western foreland leads to the conclusion that
the ice movement was controlled by the topography, which is
in harmony with the belief that " Newfoundland seems to have
been a separate area of glaciation. "f

Origin of thb Surface Features.

Parallel features. — The presence of great structural lines
with a northeastwardly trend finds expression on the surface
in control of erosion resulting in parallel ridges and valleys
having the same direction as th.e fold and faults, the softer
beds and zones of weakness having been eroded out.

Upland surf ace. — The accordance of the summit levels of
the highlands, the systematic decrease of the elevations east-
ward, the presence of well preserved flat-topped mountains at
many localities with the projected plane of their summits trun-
cating all kinds of structure and rock, the course of the Hum-
ber Kiver with its source less than a score of miles from the
eastern shore at an elevation of less than 700 feet and its mouth
on the opposite side of a mountain range 2000 feet high : these

• Schuchert, Note book. August and September, 1910.
tChamberlin and Saliebury, Earth History, vol. iii, p. 336, 1907.



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W. H. Twenhofel — Physiography of Newfoundland, 19

are considered evidence of the present dissection, but one
time perfection of a peneplain, a plain of erosion of remark-
able perfection extending over the whole of Newfoundland.*
If the valleys were filled to the level of the average mountain
summits the resulting plain would be strikingly perfect, would
be 2000 feet high on its western border and pass beneath the
sea on its eastern with an elevation of about 700 feet at the
shore. This slope probably represents the tilting that has
occurred with uplift, which, however, does not appear to have
been a simple warping uplift, but by different blocks acting as
units, of which the Long Kange is pei:haps the most conspicu-
ous. On this ancient plain the rivers were free to wander
where they would, structure and texture of rock being mini-
mized as "factors of stream control. They probably crossed
the site of the present mountain ranges and, when the land
arose, each stream struggled to maintain its position. The
Humber alone carved its way through the rising Long Eange
blocks and by developing northern and southern tnbutaries
took from other western streams their sources, but thus pre-
served their waters for the western sea.

Attempts to fix the time of the close of the cycle of erosion in
which this peneplain was carved meet with difficulty. The
latest rocks involved in the folding that probably initiated the
erosion cycle are of Pennsylvanian age and the upper wide and
flat-floored valleys are pre-glacial.

In the eastern United States throughout the Appalachians,
the existence of an extensive peneplam, completed before the
end of Cretaceous time, is now universally admitted and with
this base level that of Newfoundland is tentatively correlated,
and the period of development and close of the cycle assumed
to be the same.

Elevated valleys. — These valleys, situated at altitudes of
from 800 to 1200 feet, were probably carved during a period
of temporary stability when tne land was lower by an amount
almost equal to their present elevation. The evidences of an
older topography at this level are so evident that any possi-
bility of ascribing them wholly to the work of ice is elifninated
and to the work of this agent can merely be assigned their
U-shape and greater width. Except that they are pre-glacial
their time of origin cannot at present be determined in New-
foundland, but tne observations of numerous workers in many
parts of the Appalachians have proven the development of a
partial peneplain during Tertiary time and these elevated val-
leys were perhaps a part of that level. There are not sufficient

* Withoat discussion the writer assumes that this plain owes its origin to
mibaMal erosion and not marinei considering that the numei'oas conical
residuals and the extensive area support the assumption.



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20 W, H. Twenhofel — Physiography of Newfoundland.

data to discuss the occurrence of this level in other parts of
Newfoundland.

Scarp of the Long Range and the foreland. — These two
features seem to be causally related in their method of orip^in
and so are considered together. The absence of detailed facts
relating to the sediments along the entire base of the cliff
renders any conclusion merely tentative. The facts at present
known to the writer suggest an origin for each in two possible
ways, one far more plausible than the other. These are dis-
cussed in succeeding paragraphs.

(1) It may be assumed that the foreland is a plain resulting
from marine erosion. The presence of terraces up to 400 feet
shows that at one time sea waters covered such portions as are
below this elevation. These waters were, however, post-glacial
while the foreland's surface existed in pre-glacial time. The
general limitation of the foreland to the sediments and its
absence when the crystallines are reached favor the idea of its
production by marine erosion, which is not supported, however,
by the fact that at least three large blocks of the sediments —
Anguille Mountains, St. John Mountains, and Portland Head —
are left standing on the plain and reach the sea. Its extreme
variability in width and almost total absence where the line of
cliff reaches the sea, no matter of what kind of rock it be com-
posed, and the steepnesn and well preserved character of the
cliff face in view of the great age required on the assumption
of marine erosion render the hypothesis untenable.*

(2) It may be assumed that the scarp is a fault face along
which the present Long Kange has been elevated. The facts
practically proving this idea are : the localization of numerous
intrusions along the foot of its southern extension, its remark-
able integrity, the actual presence of great faulting near its
base at several widely removed localities, and the upturning of
the beds where these have been observed at the base of the
cliff. The horizontality of the beds, except in the immediate
vicinity of the intrusive masses, and their occasional dip
toward the mountains find in this idea a ready explanation.
On this idea the elevated blocks on the foreland and its varia-
tion in altitude are merely due to differential subsidence and
elevation, while the bays of St. George and St. John are
masses in which the depression was somewhat greater than
the rest of the surface, the straight northern coast of St. George
being the bounding fault of this bay, which, continued inland,
fixed the course of the St. George River. The upper portion
of the cliff face, that in which the elevated valleys have been

* This hypothesiB permits the assumption that the Long; Range may be
anticUnal in character. A search for data supporting this assumption
yielded negative results.



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W. H. Twenhofel — Physiography of Newfoundland. 31

carved, is the older, while the lower portion may be immediately
pre-glacial or even younger, thus explaining its well preserved
character. This hypothesis gives to the foreland surface and
that of the upraised peneplain a community of origin — both
formed when the land was a peneplain and since separated by
the faulting up of the Long Kange.

J V Physiographic History.

^j- The present physiography probably took its birth at the
\ <? close of the period of folding in which the Pennsylvanian
V i sediments were the latest involved. Then was initiated that
^ "^ cycle of erosion resulting in the peneplain, the numerous rem-
;^ nants of which are so well preserved on the flat-topped uplands
of the west coast. On the lowland thus created, made almost
perfect by the end of the Cretaceous, the rivers, free to wander,
ploughed their channels across the site of the present moun-
tains. The close of Cretaceous time is thought to have witnessed
the uplift of the highlands of the west coast to an amount
equal to about 800 feet, in which movement it is not believed
that the foreland participated to a great extent. That it was
below the wide upper valleys appears certain, otherwise they
should be found engraved on its surface. This uplift inaugu-
rated a new cycle in which these valleys were carved and the
rivers once more became adjusted to the structure and assumed
their northeast-southwest alignment. Before the completion
of this cycle it was interrupted by renewed uplift ; but suffi-
cient time had elapsed to bring the topography well on the
way toward maturity. When the movement had reached com-
pletion, the highlands of the west coast stood about 600 feet
above their present altitude, this figure being derived from
the depth of the drowned valleys :* and the distance between
their summits and the surface of the foreland was increased by
an average of about 1000 feet, the latter not participating to a
great extent in the elevation. To what extent the east side was
affected is not known but that it once was much higher appears
certain. Following the elevation the deeply submerged val-
leys of the west coast were cut. The striking U-shape of
the upper valleys and the presence of striae on the foreland
fix the time of uplift as pre-glacial.

Glacial time saw the island under a sheet of ice and then
were developed the U-shapes to the upper valleys and the
flaring out of the small vallevs cut in the cliflf face. The
topography was softened by the chiseling exerted by the ice
on its salients, and many rock basins — the beds of existing
lakes —were carved.

* It IB poBBible that a part of this depth may be dae to ice catting below'
Bea-level, although more than 100 feet has been aUowed.



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22 W. H. Tweiihofel — Physiography of Newfoundland.

Cbamplain submergence brought a loss of about 1000 feet
in the relative elevation of the west coast (the depth of the
drowning of the valleys plus the elevation of the highest
terrace) and an equivalent amount is assumed for the east.
Since that time the island has experienced relative uplift,
intermittent in its nature, to an amount equal on the west
coast to at least 400 feet. On the east coast the elevation has
been differential in character, Daly* stating that the altitude
of the highest beach (507 feet on Signal Hill, St. John)
decreases northward.

Rblation op Settlements to Coastal Physiography.

An extremely close relation exists between the location of
the settlements of the west coast and the coastal physiography.
The larger settlements owe their existence to the presence of a
land-locked harbor, and unless two such harbors are very close
together a rather large settlement may be looked for in every
one entered. Fish, alluvial deposits, and coves have been the
conditioning factoids in the location of the smaller settlements



Online LibraryJohn Elihu HallThe American journal of science → online text (page 3 of 61)