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necessary for interpretation. The chief factors concerned in

* For the opportunity of assisting in this interesting work, undertaken in
the sammer of 1910, the writer is indebted to Professor Schuchert, for whom
he acted as assistant, and Doctor Charles D. Walcott ; the work being done
under the auspices of the Peabody Museum of Yale University and the
Smithsojiian Institution. The writer is further indebted to Professors
Schuchert and Barrell for having read the paper.

Am. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 193.— January, 1912.
1



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2 W. JET. Tvmihqfel — Physiography of ]Vewfoundland.



Fig. 1.




Fig. 1. Map of Newfoundland from Rev. M. Harvey's Text Book of
Newfoundland History (1890). The northern tributaries of the Humber
should extend farther to the north and west.



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W. H, Twenhofel — Physiography of Newfoundland, 3

the production of the surface are examined and the conclusion
is reached that the uplands of Newfoundland are the remnants
left by dissection of a once almost perfect peneplain. Finally,
the relation of the western settlements to the coastal physiog-
raphy is briefly stated and a few notes are added on the
physiography of the Belle Isle coast of Labrador.

General Outline of the Island.

The general outline of Newfoundland is very irregular, the
coast being diversified by many bays and headlands, with the
result that its length is tripled if not quadrupled. For descrip-
tive purposes the island may be divided into three parts : (1)
the main body elongated east and west along the parallel of
48° 30', terminating on the west in the Long Range Mountains ;
(2) the northern peninsula, formed for the most part of the
Long Range mountains and the foreland to the west ; and (3)
the peninsula of Avalon on the southeast, almost cut oflE from
the rest of the island by Trinity and Placentia Bays. Possibly
a fourth part may be considered as made by the peninsula
lying between Placentia Bay and Fortune Bay farther to the
west; of which St. Pierre and Great and Little Miquelon
Islands may be considered the extension.

Thoroughly land-locked harbors, extending, in the case of
many, miles into the land, are common features, some of them,
ten to fifteen miles from the sea, having depths of water in
their middle portions not permitting the anchorage of ordinary
vessels.

Chakacteb of the Rocks.

The variations of the rocks in texture, hardness, and solu-
bility have been important factors of physiographic control in
the development of the Newfoundland surface, and their
regional distribution is as follows :

The northern penin^sula of Newfoundland consists of an
interior axis formed of metamorphic and igneous crystalline
rocks of Laurentian or undetermined age (Howley, Map of
Newfoundland). The axis is bordered on the northwest, from
Cape Norman to Table Point, by a belt of limestones, gen-
erally magnesian, which begin in the Lower Cambrian and
extend to about the middle of the Ordovician, having in some
places a width of twenty miles and upward. South from
Table Point to the Bay of Islands the belt is continued by thick
beds of fine-grained shale to coarse sandstone and the coarsest
of limestone conglomerate, in which blocks of interstratified
limestone and shale with lengths exceeding 260 feet are not
uncommon. The bold and rugged coast between Bonne Bay
and the north end of Port au Port Bay is composed of basic



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4 W. ST. Tioenhqfel — Physiography of Newfoundland.

igneous rocks, probably intrusive in the sediments. Where
these terminate, the limestones, shales, and conglomerates of
the north reappear, repeating the sequence but in a reverse
direction. From St. George Bay to the southwest corner of the
island the rocks are of Carboniferous age, consisting of gypsum,
thin coal beds, shale, sandstone, conglomerate, and limestone.

On the east side of the northern peninsula the section, begin-
ning in the pre-Cambrian and extending into the Silurian, con-
sists of alternating zones of limestones, slates, sandstones, and
conglomerates,* the belt varying in width from nothing at the
souSi to ten miles and upward at the north.

On the southeastern peninsula the youngest strata are of
Cambrian time, consisting of conglomerates, shales, and lime-
stones.f Beneath is the Avalonian series (Proterozoic) of
slates, sandstones, quartzites, and conglomerates.^

The interior is underlain by more or less alternating bands
of Paleozoic and Huronian sediments of varied character,
Laurentian crystallines, and great masses of post-Ordovician
intrusives, consisting of granite, diorite, and trap.§

It is readily seen from this brief description of the rocks
that they vary widely, which in consequence leads to decided
variations in topographic expression.

Stbuctube of Newfoundland.

No factor has made a more decided impress on Newfound-
land topography than that of structure, which in its broader
outlines is as follows :

On the coasts of the northern peninsula the beds depart
little from the horizontal, Logan | stating that ''in the great
northern peninsula of Newfoundland, instead of undulations,
great lines of fracture and dislocations are observed while the
strata are but little tilted " and only locally does the dip rise
to high angles. On the northern half of the west coast the
beds are generally inclined southwestward and the inclination
may rise to as high as 30^, while on the opposite side the dip
varies around 20° and is south of east.^^ On the east side the
faults, with trends approximately parallel to the Long Kange,
have displacements exceeding 1000 feet and usually the
western blocks have been elevated.** On the west side faults
strike inland from Hawke Harbor, ft Table Point, and Port-
land Head,tt the displacement at Table Point being known

♦Murray, Can. Geol. Snrv., 1865.

t Walcott, 10th Ann. Rep., U. S. Geol. Surv., p. 554, 1890.

i Walcott, BnU. Geol. Soc. America, x, pp. 219-220, 1898.

g Murray and Howley, Geol. Surv. Newfoundland, 1881.

ILogan, Can. Geol. Surv., Appendix to paper by A. Murray, p. 45, 1865.

T[ Murray, Can. Geol. Surv.. pp. 9-44, 1865.

** Logan, Ibid., pp. 872-876, 1863.

tt Logan, Ibid., pp. 292, 877, 1863.



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W. H. Twenhofel — Physiography of Newfoundland. 6

to be greater than 1000 feet. In every case the eastern mass
has been elevated and at Table Point this block has been
shoved to the north (relatively), as shown by the bending of
the beds on the downthrown mass. The trend is parallel to
the Long Range.

. At Bonne Bay and the Bay of Islands of the west coast, the
beds are in great confusion through fracturing, faulting, and
folding. Many of the folds are closed and overturned and to
add to the complexities of structure, great masses of basic
rocks are intruded into the midst of the sediments. At the
former locality, however, the original texture is not greatly
modified, for many of the fossils are still present. At the
Bay of Islands the forces were of greater magnitude, changing
the shales to slates and the limestones to marbles — a change
attended by the complete obliteration of all organic remains.

From Port au Port Bay to the southwest corner the strata
in places are quite highly disturbed. The dip shows many
variations, faulting is not uncommon, and there has been much
intrusion of basic igneous rock.*

In respect to the other parts of Newfoundland, Murrayf
states that the Avalon peninsula and " probably the whole
island . . . seems to be ranged in an alternation of great anti-
clinal and synclinal lines, independent of innumerable minor
folds, which present throughout a remarkable degree of paral-
lelism, pointing generally about N.N.E. and S.S.W. from the
true meridian, corresponding with the marked indentations of
the coast as well as the topographical features of the interior."
A great fault " intersects flie island diagonally from shore to
shore, running in an almost straight line from near the entrance
of the Little Codroy Eiver to White Bay.":|: This fault gives
off a branch northeast of Bay St. George which courses
through Grand Lake to Hall Bay, the southwest arm of Notre
Dame Bay.§

It is readily seen from this brief description that Newfound-
land structure is extremely varied and should be an important
factor of surface control.

Major Features op the Topography.

General surface. — There is no more striking feature in the
topography of Newfoundland than the marked parallelism of
the peninsulas, reentrants, lakes, rivers, ridges, and outcrops,
which in nearly every case approximate a direction about N.
28° E. Some of the most prominent of the examples are St.

♦Murray and Howley, Geol. Surv. Newfoundland, 1873, 1874; Map of
Newfonniand, 1904.

t Murray and Howley, Geol. Surv. Newfoundland, p. 139, 1868.

t Murray and Howley, Ibid., p. 90, 1866.

§ Murray and Howley, Ibid., pp. 330-332, 1873.



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6 IF. H, Twenhofel — Physiography of Newfoundland,

Mary's Bay, continued northeastwardly by Conception Bay ;
Placentia and Trinity Bays, and Fortune and Bonavista Bays,
similarly aligned ; the west and northwest coast, offset and
broken at St. George, but still essentially parallel ; the east
coast of the northern peninsula; the coast of the Avalon
peninsula ; the intrusive masses, the outcrop of the sedimep-
taries; the Long Kange; the course of the Huniber Eiver;
Grand and Eed Indian Lakes ; and Glover Island in Grand
Lake.

In general, the surface slopes southeastward. The average
elevation of the west coast is about 2000 feet, the northern
portion approximating 2100 feet or less, which rises to 2300
near the middle and decreases to 1700 feet nearOape Ray. On
the east side of the northern peninsula there do not appear to
be any elevations greater than 1200 feet. Along the south
coast the height decreases from 1700 feet at Table Mountain
to about 1350 feet north of Fortune Bay, and on the peninsula
of Avalon the highest point is 1100 feet. An axis of some-
what higher elevations extends from the neighborhood of the
Bay of Islands through the middle of the Avalon peninsula
from which the peaks decrease in height northeastward and
southwestward, but are about equal for any particular locality.
These figures of altitude, though significant, do not emphasize
the real facts, as they are taKen from conspicuous elevations
rising above the average highland surface. The decrease in
elevation of the highlands southeastward is fairly systematic,
averaging a little less than 10 feet to the mile, and two planes
placed on the western upland and meeting along a line extend-
ing from the Bay of Islands to the Avalon peninsula, if given
the average slope of the surface, would very nearly coincide
with the summits of the average highlands of Newfoundland ;
and if projected beneath the sea they would rest on, or slightly
above, the immediate sea bottom off the east coast. Through
this plane would project numerous conical peaks 100 to 400
feet high, usually formed of igneous rocks. On the west coast
the regularity and horizontality of the sky line is striking, but
on the east greater irregularity appears to exist, the country
being more dissected.

The Long Range. — The Long Range, situated along the
entire west coast, with an average elevation of 2000 feet, is the
highest range of mountains in Newfoundland. At St. George
Bay, where the Codroy- White Bay fault strikes into the land,
it is broken and offset to the southeast. Its greatest elevation
is in the Lewis Hills, about halfway between the Bay of Islands
and St. George Ba}-, where 2700 feet is reached, an elevation
purely local and exceeding by nearly 400 feet the height of
any other portion of the range. The range faces the west



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TT. H. Twenhofel — Physiography of Newfoundland. 7



with an almost vertical front, in some places
reaching the sea ; but usually with an inter-
vening foreland. To one approaching New-
foundland from Sidney to I^ort aux Basques,
the most impressive feature is the high flat-
topped upland, here rising almost vertically
from the sea — the southern extremity of the
Long Eange. If Newfoundland be observed
from the Labrador side, one feature will
attract and maintain the attention : the flat-
topped upland, standing boldly and promi-
nently in view with a low plain on either
side, widest toward Cape Norman way — the
northern extremity of the Long Range. The
sky line of the Long Kange is strikingly hori-
zontal and the appearance of an equS neight
in all its parts is not a fiction resulting from a
distant view, for it remains the same near as
well as far, while a very cursory study of
Howley's map confirms the evidence of direct
observation. At manv points in this range
are " table mountains.' Such is that forming
its terminus on the southwest and rising to an
elevation of 1700 feet. Here for fully fifty
miles parallel to the railroad, which follows
the west coast, is the steep western front, ris-
ing like a wall, little cut up by erosion and
with the top of the wall reaching to one level.
On the west side of the railroad, opposite this
table mountain, is the triangular block of the
Anguille Mountains, built upon the older
Paleozoic sediments and rising to a height of
1832 feet, more than 100 feet higher than the
mountain to the east. The name of Table
Mountain might with justice be applied to
this block. At the Bay of Islands is Mount
Blomidon, 2125 feet high, with a table tojp, in
the central portion of which is a lake. Table
Mountain at Bonne Bay, 2336 feet high, is
almost as flat on its summit as a western
prairie, the surface rising gently from the
margin toward the middle. It has been thor-
oughly shattered by the movements to which
it has been subjected, favoring the formation
of angular gravel through sun and frost action,
and were it not for a mantle of such gravel a



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8 W, H, Twenhofel — Physiography of Newfoundland.

bicycle could be ridden with ease on the top of the mountain,
a surface stated to have a length of six miles parallel to the
coast and four miles in the opposite direction. Its sides are very
steep and there are few places where it may be ascended
except with difficulty. The summit is almost bare of vegeta-
tion and that present consists of dwarfed plants occurring in a
few wet places or shallow bogs. The plane of this Bonne Bay

Fig. 3.



Fig. 8. Table Mountain, Bonne Bay, 2836 feet high. Photograph by
Charles Schuchert.

'^ table " truncates the rock of all the systems in the region, no
matter what their structure or character, the elevations rising to,
or almost to, its level and there stopping either as peaks,
ridges, or " tables."

The Long Range scarp with its elevated valleys, — The slope
of the surface of Newfoundland rises toward the west till the
summit of the Long Range is reached, where an abrupt drop
of between 1500 and 2000 feet takes place. The line of west-
ward-facing cliffs, for the most part composed of crystalline
rocks, is almost a straight one, but is broken and offset to the
southeast at St. George Bay, south of which it continues in the
same direction as a straight line. West of the cliff face the
rocks are almost wholly sedimentary and, in general, do not



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W. If. Twenhofel — Physiography of Newfoundland. 9

depart greatly from a horizontal attitude ; the general dip is
away from the cliff face, but at some localities, as the St. John
Mountains and St. George Bay, the beds dip toward the cliflE.*
In most places, the beds if projected towards the mountains
with the dip they have at the sea, would abut against the cliff
face ; but it is very probable that at its base the strata have an
entirely different attitude. Such is the case at Bonne Bay and
the Bay of Islands, and Murrayf found similar conditions
about St. George, where at the foot of the mountains the beds
" are usually very highly tilted, inclining in the opposite direc-
tion {away from the mountains) or vertical."

Erosion has done extremely little to destroy or modify this
precipitous westward-facing scarp, its integrity being well pre-
served. In but a few places like the Bay o^ Islands and St.
George Bay has a large river cut its way to the sea or pushed
its head far beyond the mountain face ; but many small valleys
have been cut in the upper portion of the wall at elevations
varying with the region, but averaging one-half to two-thirds
the height of the cliff. Most of them flare out near their
heads and flow on levels having a lesser gradient than lower
down in their courses and nearly all of them appear to head in
a wall. At Bonne Bay, where some of these valleys were
studied in detail, they present a protile similar to that which
follows (fig. 3). The upper level is flat-floored, quite wide, in
a few cases one-half mile or more, and at an elevation of about
1200 feet above the sea, or about 900 to 1000 feet below the
top of the Table Mountain wall. At Bonne Bay and the Bay
of Islands many of the lower elevations rise to about the level of
these upper valleys, where they, while not flat-topped, show an
older topography on their summits, and at least one table
mountain, that at Port au Port, rises to a level slightly less.

Their widtli is out of all proportion to the small streams
flowing in them, which move slowly from one to another of
the ponds and lakes commonly present. Lower down in their
courses they become a series of rapids and cataracts, enclosed
in steep-walled narrow gorges, the descent of which, actual
experience teaches is not only difficult but dangerous.

At Bonne Bay the upper valley level affords an easy route
of travel from that place to Trout River, a fishing settlement
about ten miles farther south on the coast. This route, after
the ascent to the upper level has been made, is a really excel-
lent one for vehicles, and the only one that is at all practicable
(see fig. 4).

*The dip at the St. John Monntains was judged from the deck of a
schooner, bat appears so plain that it can hardly be questioned,
t Murray, Geol. Surv. Newfoundland, p. 88, 1866.



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10 W. H. Twenhofd — Physiography of Newfoundland.

Foreland of the Long Range. — Along the northern and
western sides of the island, the Long KaTige is fringed by a
foreland of greater or less width. It is widest along the Strait
of Belle Isle, approaching twenty miles, but decreases to about
ten miles at Port Sanders and holds this width nearly to Bonne
Bay. From Bonne Bay to Port au Port Bay the Long Range
reaches the sea and the foreland vanishes, but reappears at St.

Fia. 4.




Fig. 4. Profiles of valleys and upland at Bonne Bay. (IMagrammatic.J

George Bay, where both shore and Long Kange are offset to
the southeast.

The surface of this lower level gives to the observer a
decided impression of flatness. Near the sea it is carved into
wide and narrow terraces, making the elevation immediate to the
shore quite variable, the average being about 75 feet. Inland,
elevations rise above 150 feet with many much higher, there
being at least three very high blocks of sediments, — Angnille
Mountains, St. John Mountains, and Portland Head. Many
parts are also low, and it is said that tidal waters go nearly to
the mountains at Paul Inlet, Parson's Pond and Portland Creek,
at each of which the shores are very low. There also appear
to be places where the land is higher on the shore than in the
backland, Mr. Thomas House, a fisherman at Table Point,
stating that the rear of the foreland in that locality is a marsh
considerably lower tlian is the shore. The presence of glacial
striee at many localities fixes the time of the carving of the
surface as pre-glacial.

Uplands of the east and' central parts. — Of the east and
central parts the writer has no first-hand knowledge, but a
study of the published maps and sections and the literature
shows that the surface consists of a series of parallel valleys
lying in the softer sediments, separated by flat-topped ridges



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W. S. TwenhofeL — Physiography of Newfoundland. 11

on which rise local elevations. Professor Schuchert, who
visited this part of the island after the writer had left for home,
states that " what we saw [on the west] was confirmed in the
eastern part of the island and the interior, although the physio-
graphic aspect is a very different one. One sees no such
foreland as we saw in western Newfoundland. The nearer one
is to the coast the more fiord-like it is " ;* but even here a
section published by Walcott in 1899,t extending from Signal
Hill, St. John's Harbor, to Portugal Cove, Conception Bay,
shows well preserved flat-topped hills.

On the granite hills of the interior, where crossed by the
railroad, " the surface is not a plane ; but a gently undulatory
one with pointed conical residual hills standing several hun-
dred feet higher,"^ a description, judging from the reports of
Murray and Howley, apparently applicable to most of the inte-
rior upland.

Murray states that two great depressions extend across the
island, one from St. George Bay through the Huraber Valley
and Deer Lake to White Bay, the other from St. George Bay
through Grand Lake to Hall Bay, their location coinciding with
the two great faults described by him.

Rivers and lakes, — The rivers and lakes of Newfoundland
are in no respect striking or peculiar with the exception of the
Humber and its tributaries. In general, the rivers flow north-
east or southwest, parallel to the ridges, along the outcrops of
the sedimentary formations. The lakes have their greatest
elongation in the same direction. Near the shore the general
aspect of the rivers is that of youth, falls and rapids being met
with at nearly every turn, with lakes in many places inter-
rupting the course of rapid flow. In the interior the rivers
flow in wide, sediment-cloaked valleys, carved in the softer
sediments, most of them consisting of chains of lakes separated
by intervals of rapid water.

The Humber Kiver with its tributaries, however, more than
atones for whatever simplicity is exhibited by its fellows. It
has two main branches, one rising far to the south, about twelve
miles from the head of St. George Bay, the other about nine
miles from the head of White Bay, at an elevation of less than
700 feet. The former flows for about fifty miles in a north-
northeast direction, where it meets the latter, which has followed
a south-southwest course for more than twenty miles. After
the junction the united stream flows almost due west for about
ten miles, where another tributary enters from the north-north-
east which has two branches ; one believed to head less than

* Schnchert, Personal letter dated October 3, 1910.

f Walcott, BuU. Geol. Soc. America, x, p. 221, fig. 6, 1899.

t Schuchert, Note book, August 26, 1910.



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12 W, n. Twenhofd — Physiography of Newfoundland,

five miles from the bottom of a western reentrant from White
Bay, while the other has its source about twelve miles from the
liead of Deer arm of Bonne Bay. Briefly stated, the Humber
in two of its tributaries rises less than a dozen miles from the
eastern sea at elevations less than 700 feet, with two other
tributaries rising but twelve miles from the sea into which it

Fig. 5.




Fig. 5. The Humber drainage. The Long Range lies between the npper
river and the coast. 1. Bay of Islands ; 2. Bonne Bay ; 8. White Bay ; 4. St.
George Bay. Bednced with some omissions from Howley's map of New-
foundland.

empties, flows entirely across the southern end of the northern
peninsula, and then in a steep V-shaped gorge dashes through
a mountain range which gradually rises toward the sea and
reaches a height of over 2000 feet where the waters of the
Humber join with those of the Gulf. In this course the river
flows across nearly every character of rock possessed by the
island and across such structural features as faults, folds, and
igneous contacts. That it is an antecedent river can hardly be
questioned.

Peninsulas and hays. — The coast of Newfoundland is
diversified by extremely deep bays and bold headlands which
on the south and north coasts are elongated in the direction of
the structural features already outlined ; but on the west and



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W. H, Twenhofel — Physiography of Newfoundland. 13



Online LibraryJohn Elihu HallThe American journal of science → online text (page 2 of 61)