The essence of physiography is the belief that land forms represent
merely a stage in the orderly development of the earth’s surface
features; that the various dynamic agents perform their characteristic
work throughout all geologic time. The formulation of principle and
processes of earth sculpture was, therefore, impossible on the
hypothesis of a ready-made earth whose features were substantially
unchangeable, except when modified by catastrophic processes. In 1821,
J. W. Wilson wrote in the Journal: “Is it not the best theory of the
earth, that the Creator, in the beginning, at least at the general
deluge, formed it with all its present grand characteristic
features?”[4] If so, a search for causes is futile, and the study of the
work performed by streams and glaciers and wind is unprofitable. The
belief in the Deluge as the one great geological event in the history of
the earth has brought it about that the speculations of Aristotle,
Herodotus, Strabo, and Ovid, and the illustrious Arab, Avicenna
(980–1037), unchecked by appeal to facts but also unopposed by
priesthood or popular prejudice, are nearer to the truth than the
intolerant controversial writings of the intellectual leaders whose
touchstone was orthodoxy. A few thinkers of the sixteenth century
revolted against the interminable repetition of error, and Peter
Severinus (1571) advised his students: “Burn up your books ... buy
yourselves stout shoes, get away to the mountains, search the valleys,
the deserts, the shores of the seas.... In this way and no other will
you arrive at a knowledge of things.” But the thoroughgoing
“diluvialist” who believed that a million species of animals could
occupy a 450–foot Ark, but not that pebbles weathered from rock or that
rivers erode, had no use for his powers of observation.
Sporadic germs of a science of land forms scattered through the
literature of the seventeenth and eighteenth centuries found an
unfavorable environment and produced inconspicuous growths. Even their
sponsors did little to cultivate them. Steno (1631–1687) mildly
suggested that surface sculpturing, particularly on a small scale, is
largely the work of running water, and Guettard (1715–1786), a truly
great mind, grasped the fundamental principles of denudation and
successfully entombed his views as well as his reputation in scores of
books and volumes of cumbrous diffuse writing.
At the beginning of the nineteenth century a sufficient body of
principles had been established to justify the recognition of an earth
science, geology, and the 195 volumes of the Journal thus far published
carry a large part of the material which has won approval for the new
science and given prominence to American thought. From the pages in the
Journal, the progress of geology may be illustrated by tracing the
fluctuation in the development of fact and theory as relates to valleys
and glacial features, the subjects to which this chapter is devoted.
_The Interpretation of Valleys._
_The Pioneers._
Desmarest (1725–1815) might be styled the father of physiography. By
concrete examples and sound induction he established (1774) the doctrine
that the valleys of central France are formed by the streams which
occupy them. He also made the first attempt to trace the history of a
landscape through its successive stages on the basis of known causes.
His methods and reasoning are practically identical with those of Dutton
working in the ancient lavas of New Mexico; and Whitney’s description of
the Table Mountains of California might well have appeared in
Desmarest’s memoirs.[5] The teachings of Desmarest were strengthened and
expanded by DeSaussure (1740–1799), the sponsor for the term, “Geology,”
(1779) who saw in the intimate relation of Alpine streams and valleys
the evidence of erosion by running water (1786).
The work of these acknowledged leaders of geological thought attracted
singularly little attention on the Continent, and Lamarck’s volume on
denudation (Hydrogéologie), which appeared in 1802, although an
important contribution, sank out of sight. But the seed of the French
school found fertile ground in Edinburgh, the center of the geological
world during the first quarter of the nineteenth century. Hutton’s
“Theory of the Earth, with Proofs and Illustrations,” in which the
guidance of DeSaussure and Desmarest is gratefully acknowledged,
appeared in 1795. The original publication aroused only local interest,
but when placed in attractive form by Playfair’s “Illustrations of the
Huttonian Theory” (1802), the problem of the origin and development of
land forms assumed a commanding position in geological thought. Hutton
was peculiarly fortunate in his environment. He had the support and
assistance of a group of able scientific colleagues as well as the
bitter opposition of Jameson and of the defenders of orthodoxy. His
views were discussed in scientific publications and found their way to
literary and theological journals. Hutton’s conception of the processes
of land sculpture—slow upheaving and slow degradation of mountains,
differential weathering, and the carving of valleys by streams—has a
very modern aspect. Playfair’s book would scarcely be out of place in a
twentieth century class room. The following paragraphs are quoted from
it:[6]
“... A river, of which the course is both serpentine and deeply
excavated in the rock, is among the phenomena, by which the slow waste
of the land, and also the cause of that waste, are most directly
pointed out.
The structure of the vallies among mountains, shews clearly to what
cause their existence is to be ascribed. Here we have first a large
valley, communicating directly with the plain, and winding between
high ridges of mountains, while the river in the bottom of it descends
over a surface, remarkable, in such a scene, for its uniform
declivity. Into this, open a multitude of transverse or secondary
vallies, intersecting the ridges on either side of the former, each
bringing a contribution to the main stream, proportioned to its
magnitude; and, except where a cataract now and then intervenes, all
having that nice adjustment in their levels, which is the more
wonderful, the greater the irregularity of the surface. These
secondary vallies have others of a smaller size opening into them;
and, among mountains of the first order, where all is laid out on the
greatest scale, these ramifications are continued to a fourth, and
even a fifth, each diminishing in size as it increases in elevation,
and as its supply of water is less. Through them all, this law is in
general observed, that where a higher valley joins a lower one, of the
two angles which it makes with the latter, that which is obtuse is
always on the descending side; ... what else but the water itself,
working its way through obstacles of unequal resistance, could have
opened or kept up a communication between the inequalities of an
irregular and alpine surface....
... The probability of such a constitution [arrangement of valleys]
having arisen from another cause, is, to the probability of its having
arisen from the running of water, in such a proportion as unity bears
to a number infinitely great.
... With Dr. Hutton, we shall be disposed to consider those great
chains of mountains, which traverse the surface of the globe, as cut
out of masses vastly greater, and more lofty than any thing that now
remains.
From this gradual change of lakes into rivers, it follows, that a lake
is but a temporary and accidental condition of a river, which is every
day approaching to its termination; and the truth of this is attested,
not only by the lakes that have existed, but also by those that
continue to exist.”
_Steps Backward._
Even Hutton’s clear reasoning, firmly buttressed by concrete examples,
was insufficient to overcome the belief in ready-made or violently
formed valleys and original corrugations and irregularities of mountain
surface. The pages of the Journal show that the principles laid down by
Playfair were too far in advance of the times to secure general
acceptance. In the first volume of the Journal, the gorge of the French
Broad River is assigned by Kain to “some dreadful commotion in nature
which probably shook these mountains to their bases,”[7] and the gorge
of the lower Connecticut is considered by Hitchcock (1824)[8] as a
breach which drained a series of lakes “not many centuries before the
settlement of this country.” The prevailing American and English view
for the first quarter of the nineteenth century is expressed in the
reviews in this Journal, where the well-known conclusions of Conybeare
and Phillips that streams are incompetent to excavate valleys are quoted
with approval and admiration is expressed for Buckland’s famous
“Reliquiæ Diluvianæ,” a 300–page quarto volume devoted to proof of a
deluge. The professor at Yale, Silliman, and the professor at Oxford,
Buckland, saw that an acceptance of Hutton’s views involved a
repudiation of the Biblical flood, and much space is devoted to
combating these “erroneous” and “unscientific” views. For example,
Buckland says:[9]
“... The general belief is, that existing streams, avalanches and
lakes, bursting their barriers, are sufficient to account for all
their phenomena, and not a few geologists, especially those of the
Huttonian school, at whose head is Professor Playfair, have till
recently been of this opinion.... But it is now very clear to almost
every man, who impartially examines the facts in regard to existing
vallies, that the causes now in action, mentioned above, are
altogether inadequate to their production; nay, that such a
supposition would involve a physical impossibility. We do not believe
that one-thousandth part of our present vallies were excavated by the
power of existing streams.... In very many cases of large rivers, it
is found, that so far from having formed their own beds, they are
actually in a gradual manner filling them up.
Again; how happens it that the source of a river is frequently below
the head of a valley, if the river excavated that valley?
The most powerful argument, however, in our opinion, against the
supposition we are combating, is the phenomena of transverse and
longitudinal valleys; both of which could not possibly have been
formed by existing streams.”
Phillips writes in 1829:[10] “The excavation of valleys can be ascribed
to no other cause than a great flood of water which overtopped the
hills, whose summits those vallies descend.”
Faith in Noah’s flood as the dominant agent of erosion rapidly lost
ground through the teaching of Lyell after 1830, but the theory of
systematic development of landscapes by rivers gained little. In fact,
Scrope in 1830,[11] in showing that the entrenched meanders of the
Moselle prove gradual progressive stream work, was in advance of his
English contemporary. Judged by contributions to the Journal, Lyell’s
teaching served to standardize American opinion of earth sculpture
somewhat as follows: The ocean is the great valley maker, but rivers
also make them; the position of valleys is determined by original or
renewed surface inequalities or by faulting; exceptional
occurrences—earthquakes, bursting of lakes, upheavals and
depressions—have played an important part. Hayes (1839)[12] thought that
the surface of New York was essentially an upraised sea-bottom modified
by erosion of waves and ocean currents. Sedgwick (1838)[13] considered
high-lying lake basins proof of valleys which were shaped under the sea.
Many of the valleys in the Chilian Cordillera were thought by Darwin
(1844) to have been the work of waves and tides, and water gaps are
ascribed to currents “bursting through the range at those points where
the strata have been least inclined and the height consequently is
less.” Speaking of the magnificent stream-cut canyons of the Blue
Mountains of New South Wales, gorges which lead to narrow exits through
monoclines, Darwin says: “To attribute these hollows to alluvial action
would be preposterous.”[14]
The influence of structure in the formation of valleys is emphasized by
many contributors to the Journal. Hildreth in 1836, in a valuable
paper,[15] which is perhaps the first detailed topographic description
of drainage in folded strata, expresses the opinion that the West
Virginia ridges and valleys antedated the streams and that water gaps
though cut by rivers involve pre-existing lakes. Geddes (1826)[16]
denied that Niagara River cut its channel and speaks of valleys which
“were valleys e’er moving spirit bade the waters flow.” Conrad
(1839)[17] discussed the structural control of the Mohawk, the Ohio, and
the Mississippi, and Lieutenant Warren (1859)[18] concluded that the
Niobrara must have originated in a fissure. According to Lesley
(1862)[19] the course of the New River across the Great Valley and into
the Appalachians “striking the escarpment in the face” is determined by
the junction of anticlinal structures on the north with faulted
monoclines toward the south; a conclusion in harmony with the views of
Edward Hitchcock (1841)[17] that major valleys and mountain passes are
structural in origin and that even subordinate folds and faults may
determine minor features. “Is not this a beautiful example of
prospective benevolence on the part of the Deity, thus, by means of a
violent fracture of primary mountains, to provide for easy
intercommunication through alpine regions, countless ages afterwards!”
The extent of the wandering from the guidance of DeSaussure and Playfair
after the lapse of 50 years is shown by students of Switzerland. Alpine
valleys to Murchison (1851) were bays of an ancient sea; Schlaginweit
(1852) found regional and local complicated crustal movements a
satisfactory cause, and Forbes (1863) saw only glaciers.
_Valleys Formed by Rivers._
One strong voice before 1860 appears to have called Americans back to
truths expounded by Desmarest and Hutton. Dana in 1850[20] amply
demonstrated that valleys on the Pacific Islands owe neither their
origin, position or form to the sea or to structural factors. They are
the work of existing streams which have eaten their way headwards. Even
the valleys of Australia cited by Darwin as type examples of ocean work
are shown to be products of normal stream work. Dana went further and
gave a permanent place to the Huttonian idea that many bays, inlets, and
fiords are but the drowned mouths of stream-made valleys. In the same
volume in which these conclusions appeared, Hubbard (1850)[21] announced
that in New Hampshire the “deepest valleys are but valleys of erosion.”
The theory that valleys are excavated by streams which occupy them was
all but universally accepted after F. V. Hayden’s description[22] of
Rocky Mountain gorges (1862) and Newberry’s interpretation of the
canyons of Arizona (1862); but the scientific world was poorly prepared
for Newberry’s statement:[23]
“Like the great canons of the Colorado, the broad valleys bounded by
high and perpendicular walls _belong to a vast system of erosion, and
are wholly due to the action of water_.... The first and most
plausible explanation of the striking surface features of this region
will be to refer them to that embodiment of resistless power—the sword
that cuts so many geological knots—volcanic force. The Great Canon of
the Colorado would be considered a vast fissure or rent in the earth’s
crust, and the abrupt termination of the steps of the table lands as
marking lines of displacement. This theory though so plausible, and so
entirely adequate to explain all the striking phenomena, lacks a
single requisite to acceptance, and that is _truth_.”
With such stupendous examples in mind, the dictum of Hutton seemed
reasonable: “there is no spot on which rivers may not formerly have
run.”
_Denudation by Rivers._
The general recognition of the competency of streams to form valleys was
a necessary prelude to the broader view expressed by Jukes (1862)[24]
“The surfaces of our present lands are as much carved and sculptured
surfaces as the medallion carved from the slab, or the statue
sculptured from the block. They have been gradually reached by the
removal of the rock that once covered them, and are themselves but of
transient duration, always slowly wasting from decay.”
Contributions to the Journal between 1850 and 1870 reveal a tendency to
accept greater degrees of erosion by rivers, but the necessary
end-product of subaërial erosion—a plain—is first clearly defined by
Powell in 1875.[25] In formulating his ideas Powell introduced the term
“base-level,” which may be called the germ word out of which has grown
the “cycle of erosion,” the master key of modern physiographers. The
original definition of base-level follows:
“We may consider the level of the sea to be a grand base-level, below
which the dry lands cannot be eroded; but we may also have, for local
and temporary purposes, other base-levels of erosion, which are the
levels of the beds of the principal streams which carry away the
products of erosion. (I take some liberty in using the term ‘level’ in
this connection, as the action of a running stream in wearing its
channel ceases, for all practical purposes, before its bed has quite
reached the level of the lower end of the stream. What I have called
the base-level would, in fact, be an imaginary surface, inclining
slightly in all its parts toward the lower end of the principal stream
draining the area through which the level is supposed to extend, or
having the inclination of its parts varied in direction as determined
by tributary streams.)”
Analysis of Powell’s view has given definiteness to the distinction
between “base-level,” an imaginary plane, and “a nearly featureless
plain,” the actual land surface produced in the last stage of subaërial
erosion.
Following their discovery in the Colorado Plateau Province, denudation
surfaces were recognized on the Atlantic slope and discussed by McGee
(1888),[26] in a paper notable for the demonstration of the use of
physiographic methods and criteria in the solution of stratigraphic
problems. Davis (1889)[27] described the upland of southern New England
developed during Cretaceous time, introducing the term “peneplain,” “a
nearly featureless plain.” The short-lived opposition to the theory of
peneplanation indicates that in America at least the idea needed only
formulation to insure acceptance.
It is interesting to note that surfaces now classed as peneplains were
fully described by Percival (1842),[28] who assigned them to structure,
and by Kerr (1880),[29] who considered glaciers the agent. In Europe
“plains of denudation” have been clearly recognized by Ramsay (1846),
Jukes (1862), A. Geikie (1865), Foster and Topley (1865), Maw (1866),
Wynne (1867), Whitaker (1867), Macintosh (1869), Green (1882),
Richthofen (1882), but all of them were looked upon as products of
marine work, and writers of more recent date in England seem reluctant
to give a subordinate place to the erosive power of waves. Americans, on
the other hand, have been thinking in terms of rivers, and the great
contribution of the American school is not that peneplains exist, but
that they are the result of normal subaërial erosion. More precise field
methods during the past decade have revealed the fact that no one agent
is responsible for the land forms classed as peneplains; that not only
rivers and ocean, but ice, wind, structure, and topographic position
must be taken into account.
The recognition of rivers as valley-makers and of the final result of
stream work necessarily preceded an analysis of the process of subaërial
erosion. The first and last terms were known, the intermediate terms and
the sequence remained to be established. A significant contribution to
this problem was made by Jukes (1862).[34]
“... I believe that the lateral valleys are those which were first
formed by the drainage running directly from the crests of the chains,
the longitudinal ones being subsequently elaborated along the strike
of the softer or more erodable beds exposed on the flanks of those
chains.”
Powell’s discussion of antecedent and consequent drainage (1875) and
Gilbert’s chapter on land sculpture in the Henry Mountain report (1880)
are classics, and McGee’s contribution[30] contains significant
suggestions, but the master papers are by Davis,[31] who introduces an
analysis of land forms based on structure and age by the statement:
“Being fully persuaded of the gradual and systematic evolution of
topographical forms it is now desired ... to seek the causes of the
location of streams in their present courses; to go back if possible
to the early date when central Pennsylvania was first raised from the
sea, and trace the development of the several river systems then
implanted upon it from their ancient beginning to the present time.”
That such a task could have been undertaken a quarter of a century ago
and to-day considered a part of everyday field work shows how completely
the lost ground of a half century has been regained and how rapid the
advance in the knowledge of land sculpture since the canyons of the
Colorado Plateau were interpreted.
_Features Resulting from Glaciation._
_The Problem Stated._
Early in the nineteenth century when speculation regarding the interior
of the earth gave place in part to observations of the surface of the
earth, geologists were confronted with perhaps the most difficult
problem in the history of the science. As stated by the editor of the
Journal in 1821:[32]
“The almost universal existence of rolled pebbles, and boulders of
rock, not only on the margin of the oceans, seas, lakes, and rivers;
but their existence, often in enormous quantities, in situations quite
removed from large waters; inland,—in high banks, embedded in strata,
or scattered, occasionally, in profusion, on the face of almost every
region, and sometimes on the tops and declivities of mountains, as
well as in the vallies between them; their entire difference, in many
cases, from the rocks in the country where they lie—rounded masses and
pebbles of primitive rocks being deposited in secondary and alluvial
regions, and vice versa; these and a multitude of similar facts have
ever struck us as being among the most interesting of geological
occurrences, and as being very inadequately accounted for by existing
theories.”
The phenomena demanding explanation—jumbled masses of “diluvium,”
polished and striated rock, bowlders distributed with apparent disregard
of topography—were indeed startling. Even Lyell, the great exponent of
uniformitarianism, appears to have lost faith in his theories when
confronted with facts for which known causes seemed inadequate. The
interest aroused is attested by 31 titles in the Journal during its
first two decades, articles which include speculations unsupported by
logic or fact, field observation unaccompanied by explanation, field
observation with fantastic explanation, _ex-cathedra_ pronouncements by
prominent men, sound reasoning from insufficient data, and unclouded
recognition of cause and effect by both obscure and prominent men. With
little knowledge of glaciers, areal geology, or of structure and
composition of drift, all known forces were called in: normal
weathering, catastrophic floods, ocean currents, waves, icebergs,
glaciers, wind, and even depositions from a primordial atmosphere
(Chabier, 1823). Human agencies were not discarded. Speaking of a
granite bowlder at North Salem, New York, described by Cornelius
(1820)[33] as resting on limestone, Finch (1824)[34] says: “it is a
magnificent cromlech and the most ancient and venerable monument which
America possesses.” In the absence of a known cause, catastrophic
agencies seem reasonable.
_The Deluge._
In the seventh volume of the Journal (1824)[35] we read:
“After the production of these regular strata of sand, clay,
limestone, &c. came a terrible irruption of water from the north, or
northwest, which in many places covered the preceding formations with
diluvial gravel, and carried along with it those immense masses of
granite, and the older rocks, which attest to the present day the
destruction and ruin of a former world.”
Another author remarks:
“We find a mantle as it were of sand and gravel indifferently covering
all the solid strata, and evidently derived from some convulsion which
has lacerated and partly broken up those strata....”
The catastrophe favored by most geologists was floods of water violently
released—“we believe,” says the editor, “that all geologists agree in
imputing ... the diluvium to the agency of a deluge at one period or
another.”[36] Such conclusions rested in no small way upon Hayden’s
well-known treatise on surficial deposits (1821),[37] a volume which
deserves a prominent place in American geological literature. Hayden
clearly distinguished the topographic and structural features of the
drift but found an adequate cause in general wide-spread currents which
“flowed impetuously across the whole continent ... from north east to
south west.” In reviewing Hayden’s book Silliman remarks:
“The general cause of these currents Mr. Hayden concludes to be the
deluge of Noah. While no one will object to the propriety of ascribing
very many, probably most of our alluvial features, to that
catastrophe, we conceive that neither Mr. Hayden, nor any other man,
is bound to prove the immediate physical cause of that vindictive
infliction.
We would beg leave to suggest the following as a cause which _may_
have aided in deluging the earth, and which, were there occasion,
_might_ do it again.
The existence of enormous caverns in the bowels of the earth, (so
often imagined by authors,) appears to be no very extravagant
assumption. It is true it cannot be proved, but in a sphere of eight
thousand miles in diameter, it would appear in no way extraordinary,
that many cavities might exist, which collectively, or even singly,
might well contain much more than all our oceans, seas, and other
superficial waters, none of which are probably more than a few miles
in depth. If these cavities communicate in any manner with the oceans,
and are (as if they exist at all, they probably are,) filled with
water, there exist, we conceive, agents very competent to expel the
water of these cavities, and thus to deluge, at any time, the dry
land.”
The teachings of Hayden were favorably received by Hitchcock, Struder,
and Hubbard, and many Europeans. They found a champion in Jackson, who
states (1839):[38]
“From the observations made upon Mount Ktaadn, it is proved, that the
current did rush over the summit of that lofty mountain, and
consequently the diluvial waters rose to the height of more than 5,000
feet. Hence we are enabled to prove, that the ancient ocean, which
rushed over the surface of the State, was at least a mile in depth,
and its transporting power must have been greatly increased by its
enormous pressure.”
Gibson, a student of western geology, reaches the same conclusion
(1836):[39]
“That a wide-spread current, although not, as imagined, fed from an
inland sea, once swept over the entire region between the Alleghany
and the Rocky Mountains is established by plenary proof.”
Professor Sedgwick (1831) thought the sudden upheaval of mountains
sufficient to have caused floods again and again. The strength of the
belief in the Biblical flood, during the first quarter of the 19th
century, may be represented by the following remarks of Phillips
(1832):[40]
“Of many important facts which come under the consideration of
geologists, the ‘Deluge’ is, perhaps, the most remarkable; and it is
established by such clear and positive arguments, that if any one
point of natural history may be considered as proved, the deluge must
be admitted to have happened, because it has left full evidence in
plain and characteristic effects _upon the surface of the earth_.”
However, the theory of deluges, whether of ocean or land streams, did
not hold the field unopposed. In 1823, Granger,[41] an observer whose
contributions to science total only six pages, speaks of the striæ on
the shore of Lake Erie as
“having been formed by the powerful and continued attrition of some
hard body.... To me, it does not seem possible that water under any
circumstances, could have effected it. The flutings in width, depth,
and direction, are as regular as if they had been cut out by a
grooving plane. This, running water could not effect, nor could its
operation have produced that glassy smoothness, which, in many parts,
it still retains.”
Hayes and also Conrad expressed similar views in the Journal 16 years
later.
The idea that ice was in some way concerned with the transportation of
drift has had a curious history. The first unequivocal statement, based
on reading and keen observation, was made in the Journal by Dobson in
1826:[42]
“I have had occasion to dig up a great number of bowlders, of red
sandstone, and of the conglomerate kind, in erecting a cotton
manufactory; and it was not uncommon to find them worn smooth on the
under side, as if done by their having been dragged over rocks and
gravelly earth, in one steady position. On examination, they exhibit
scratches and furrows on the abraded part; and if among the minerals
composing the rock, there happened to be pebbles of feldspar, or
quartz, (which was not uncommon,) they usually appeared not to be worn
so much as the rest of the stone, preserving their more tender parts
in a ridge, extending some inches. When several of these pebbles
happen to be in one block, the preserved ridges were on the same side
of the pebbles, so that it is easy to determine which part of the
stone moved forward, in the act of wearing.
These bowlders are found, not only on the surface, but I have
discovered them a number of feet deep, in the earth, in the hard
compound of clay, sand, and gravel....
I think we cannot account for these appearances, unless we call in the
aid of ice along with water, and that they have been worn by being
suspended and carried in ice, over rocks and earth, under water.”
In Dobson’s day the hypothesis of “gigantic floods,” “debacles,”
“resistless world-wide currents,” was so firmly entrenched that the
voice of the observant layman found no hearers, and a letter from Dobson
to Hitchcock written in 1837 and containing additional evidence and
argument remained unpublished until Murchison, in 1842,[43] paid his
respects to the remarkable work of a remarkable man.[44]
“I take leave of the glacial theory in congratulating American science
in having possessed the original author of the best glacial theory,
though his name had escaped notice; and in recommending to you the
terse argument of Peter Dobson, a previous acquaintance with which
might have saved volumes of disputation on both sides of the
Atlantic.”
_Glaciers vs. Icebergs._
The glacial theory makes its way into geological literature with the
development of Agassiz (1837) of the views of Venetz (1833) and
Charpentier (1834), that the glaciers of the Alps once had greater
extent. The bold assumption was made that the surface of Europe as far
south as the shores of the Mediterranean and Caspian seas was covered by
ice during a period immediately preceding the present. The kernel of the
present glacial theory is readily recognizable in these early works, but
it is wrapped in a strange husk: it was assumed that the Alps were
raised by a great convulsion under the ice and that the erratics slid to
their places over the newly made declivities. The publication of the
famous “Etudes sur les Glaciers” (1840), remarkable alike for its
clarity, its sound inductions, and wealth of illustrations, brought the
ideas of Agassiz more into prominence and inaugurated a 30–years’ war
with the proponents of currents and icebergs. The outstanding objections
to the theory were the requirement of a frigid climate and the demand
for glaciers of continental dimensions; very strong objections, indeed,
for the time when fossil evidence was not available, the great polar ice
sheets were unexplored, and the distinction between till and waterlaid
drift had not been established.
The glacial theory was cordially adopted by Buckland (1841)[45] and in
part by Lyell in England but viewed with suspicion by Sedgwick, Whewell,
and Mantell. In America the response to the new idea was immediate.
Hitchcock (1841)[46] concludes an able discussion with the statement:
“So remarkably does it solve most of the phenomena of diluvial action,
that I am constrained to believe its fundamental principles to be
founded in truth.”
The theory formed the chief topic of discussion at the third and fourth
meetings of the Association of American Geologists and Naturalists
(1842, 1843) under the lead of a committee on drift consisting of
Emmons, W. B. Rogers, Vanuxem, Nicollet, Jackson, and J. L. Hayes. The
result of these discussions was a curious reaction. Hitchcock complained
that he “had been supposed to be an advocate for the unmodified glacial
theory, but he had never been a believer in it,” and Jackson spoke for a
number of men when he stated:[47]
“This country exhibits no proofs of the glacial theory as taught by
Agassiz but on the contrary the general bearing of the facts is
against that theory.... Many eminent men incautiously embraced the new
theory, which within two or three years from its promulgation, had
been found utterly inadequate, and is now abandoned by many of its
former supporters.”
Out of this symposium came also the strange contribution of H. D. Rogers
(1844),[48] who cast aside the teachings of deduction and observation
and returned to the views of the Medievalists.
“If we will conceive, then, a wide expanse of waters, less perhaps
than one thousand feet in depth, dislodged from some high northern or
circumpolar basin, by a general lifting of that region of perhaps a
few hundred feet, and an equal subsidence of the country south, and
imagine this whole mass converted by earthquake pulsations of the
breadth which such undulations have, into a series of stupendous and
rapid-moving waves of translation, helped on by the still more rapid
flexures of the floor over which they move, and then advert to the
shattering and loosening power of the tremendous jar of the
earthquake, we shall have an agent adequate in every way to produce
the results we see, to float the northern ice from its moorings, to
rip off, assisted with its aid, the outcrops of the hardest strata, to
grind up and strew wide their fragments, to scour down the whole rocky
floor, and, gathering energy with resistance, to sweep up the slopes
and over the highest mountains.”
Because of the prominence of their author, Rogers’s views exerted some
influence and seemingly received support from England through the
elaborate mathematic discussions of Whewell (1848), who considered the
drift as “irresistible proof of paroxysmal action,” and Hopkins (1852),
who contended for “currents produced by repeated elevatory movements.”
After his arrival in America (1846), Agassiz’s influence was felt, and
his paper on the erratic phenomena about Lake Superior (1850),[49] in
which he called upon the advocates of water-borne ice to point out the
barrier which caused the current to subside, produced a salutary effect;
yet Desor (1852)[50] states that in the region described by Agassiz “the
assumption [of a general ice cap] is no longer admissible,” and that the
bowlders on Long Island “were transported on ice rafts along the sea
shore and stranded on the ridges and eminences which were then shoals
along the coast.” Twenty years of discussion were insufficient to
establish the glacial theory either in Europe or America. The consensus
of opinion among the more advanced thinkers in 1860 is expressed by
Dana:[51]
“In view of the whole subject, it appears reasonable to conclude that
the Glacier theory affords the best and fullest explanation of the
phenomena over the general surface of the continents, and encounters
the fewest difficulties. But icebergs have aided beyond doubt in
producing the results along the borders of the continents, across
ocean-channels like the German Ocean and the Baltic, and possibly over
great lakes like those of North America. Long Island Sound is so
narrow that a glacier may have stretched across it.”
Papers in the Journal of 1860–70 show a prevailing belief in icebergs,
but the evidence for land ice was accumulating as the deposits became
better known, and in 1871 field workers speak in unmistakable tones:[52]
“It is still a mooted question in American geology whether the events
of the Glacial era were due to _glaciers_ or _icebergs_.... American
geologists are still divided in opinion, and some of the most eminent
have pronounced in favor of icebergs.
Since, then, icebergs cannot pick up masses tons in weight from the
bottom of a sea, or give a general movement southward to the loose
material of the surface; neither can produce the abrasion observed
over the rocks under its various conditions; and inasmuch as all
direct evidence of the submergence of the land required for an iceberg
sea over New England fails, the conclusion appears inevitable that
icebergs had nothing to do with the drift of the New Haven region, in
the Connecticut valley; and, therefore, that the Glacial era in
central New England was a _Glacier_ era.”
Matthew (1871)[53] reached the same conclusion for the Lower Provinces
of Canada. In spite of the increasing clarity of the evidence, the
battle for the glacial theory was not yet won. The remaining opponents
though few in number were distinguished in attainments. Dawson clung to
the outworn doctrine until his death in 1899.
An interesting feature of the history of glacial theories is the
calculation by Maclaren (1842)[54] that the amount of water abstracted
from the seas to form the hypothetical ice sheet would lower the ocean
level 350 feet—an early form of the glacial control hypothesis (see
Daly[55]).
_Extent of Glacial Drift._
By the middle of the nineteenth century, it was recognized that the
“drift,” whatever its origin, was not of world-wide extent. In America
its characteristic features were found best developed north of latitude
40 degrees; in Europe, the Alps, the Scottish Highlands, and Scandinavia
were recognized as type areas. The limits were unassigned, partly
because the field had not been surveyed, but largely because criteria
for the recognition of drift had not been established. The well-known
hillocks and ridges of “diluvium” and “alluvium” and “drift” of New
Jersey and Ohio, and the mounds of the Missouri Cotou elaborately
described by Catlin (1840)[56] bore little resemblance to the walls of
unsorted rock which stand as moraines bordering Alpine glaciers. The
Orange sand of Mississippi was included in the drift by Hilgard
(1866),[57] and the gravels at Philadelphia by Hall (1876).[58] Stevens
(1873)[59] described trains of glacial erratics at Richmond, Virginia,
and William B. Rogers (1876)[60] accounts for certain deposits in the
Potomac, James, and Roanoke rivers by the presence of Pleistocene ice
tongues or swollen glacial rivers, and remarks: “It is highly probable
that glacial action had much to do with the original accumulation of the
rocky debris on the flanks of the Blue Ridge, and in the Appalachian
valleys beyond.” Kerr (1881)[61] referred the ancient erosion surface of
the Piedmont belt in North Carolina to glacial denudation, De la Beche
compared the drift of Jamaica with that of New England, and Agassiz
interpreted soils of Brazil as glacial.
The first detailed description and unequivocal interpretation of either
terminal or recessional moraines is from the pen of Gilbert (1871),[62]
geologist of the Ohio Survey. In discussing the former outlet of Lake
Erie through the Fort Wayne channel, Gilbert writes:
“The page of history recorded in these phenomena is by no means
ambiguous. The ridges, or, more properly, the ridge which determines
the courses of the St. Joseph and St. Marys rivers is a buried
terminal moraine of the glacier that moved southwestward through the
Maumee valley. The overlying Erie Clay covers it from sight, but it is
shadowed forth on the surface of that deposit, as the ground is
pictured through a deep and even canopy of snow. Its irregularly
curved outline accords intimately with the configuration of the
valley, and with the direction of the ice markings; its concavity is
turned toward the source of motion; its greatest convexity is along
the line of least resistance.
South of the St. Marys river are other and numerous moraines
accompanied by glacial striæ. Their character and courses have not yet
been studied; but their presence carries the mind back to an epoch of
the cold period, when the margin of the icefield was farther south,
and the glacier of the Maumee valley was merged in the general mass.
As the mantle of ice grew shorter—and, in fact, at every stage of its
existence—its margin must have been variously notched and lobed in
conformity with the contour of the country, the higher lands being
first laid bare by the encroaching secular summer. Early in the
history of this encroachment the glacier of the Maumee valley
constituted one of these lobes, and has recorded its form in the two
moraines that I have described.”
Three years after the recognition of moraines in the Maumee valley,
Chamberlin (1874)[63] showed that the seemingly disorganized mounds and
basins and ridges known as the Kettle range of Wisconsin is the terminal
moraine of the Green Bay glacier. At an earlier date (1864) Whittlesey
interpreted the kettles of the Wisconsin moraine as evidence of ice
blocks from a melting glacier and presented a map showing the “southern
limit of boulders and coarse drift.” In 1876 attention was called to the
terminal moraine of New England by G. Frederick Wright, who assigns the
honor of discovery to Clarence King.
[Illustration: G K Gilbert]
With the observations of Gilbert, Chamberlin, and King in mind, the
terminal moraine was traced by various workers across the United States
and into Canada and the extent of glacial cover revealed. Following 1875
the pages of the Journal contain many contributions dealing with the
origin and structure of moraines, eskers, kames, and drumlins. Before
1890 twenty-eight papers on the glacial phenomena of the Erie and Ohio
basin alone had appeared. By 1900 substantial agreement had been reached
regarding the significant features of the drift, the outline history of
the Great Lakes had been written, and the way had been paved for
stratigraphic studies of the Pleistocene, which bulk large in the pages
of the Journal for the last two decades.
_Epochs of Glaciation._
For a decade following the general acceptance of the glacial origin of
“diluvium,” the deposits were embraced as “drift” and treated as the
products of one long period of glacial activity, and throughout the
controversy of iceberg and glacier the unity of the glacial period was
unquestioned. Beds of peat and fossiliferous lacustrine deposits in
Switzerland, England, and in America and the recognition of an “upper”
and a “lower” diluvium by Scandinavian geologists suggested two epochs,
and as the examples of such deposits increased in number and it became
evident that the plant fossils represented forms demanding a genial
climate and that the phenomena were seen in many countries, the belief
grew that minor fluctuations or gradual recession of an ice sheet were
inadequate to account for the phenomena observed.
It is natural that this problem should have found its solution in
America, where the Pleistocene is admirably displayed, and where the
State and Federal surveys were actively engaged in areal mapping. In
1883 Chamberlin[64] presented his views under the bold title,
“Preliminary Paper on the Terminal Moraine of the Second Glacial Epoch,”
and the existence of deposits of two or more ice sheets and the features
of interglacial periods were substantially established by the
interesting debate in the Journal led by Chamberlin, Wright, Upham and
Dana.[65] Contributions since 1895 have been concerned with the degree
rather than the fact of complexity, and continued study has resulted in
the general recognition of five glacial stages in North America and four
in Europe.
_The Loess as a Glacial Deposit._
A curious side-product of the study of glaciation in North America is
the controversy over the origin of loess. The interest aroused is
indicated by scores of papers in American periodicals and State reports
of the last quarter of the 19th century—papers which bear the names of
prominent geologists.
The “loess” in the valley of the Rhine had long been known, but the
subject assumed prominence by the publication in 1866 of Pumpelly’s
Travels in China.[66] Wide-spread deposits 200 to 1,000 feet thick were
described as very fine-grained yellowish earth of distinctive structure
without stratification but penetrated by innumerable tubes and
containing land or fresh-water shells. Pumpelly considered these
deposits lacustrine, a view which found general acceptance though
combated by Kingsmill (1871),[67] who argued for marine deposition.
Baron Von Richthofen’s classic on China, which appeared in 1877,
amplifies the observations of Pumpelly and marshals the evidence to
support the hypothesis that the loess is wind-laid both on dry land and
within ancient salt lakes. The conclusions of Von Richthofen were
adopted by Pumpelly whose knowledge of the Chinese deposits,
supplemented by studies in Missouri, of which State he was director of
the Geological Survey in 1872–73, placed him in position to form a
correct judgment. He says:[68]
“Recognizing from personal observation the full identity of character
of the loess of northern China, Europe and the Missouri Valley, I am
obliged to reject my own explanation of the origin of the Chinese
deposits, and to believe with Richthofen that the true loess, wherever
it occurs, is a sub-aerial deposit, formed in a dry central region,
and that it owes its structure to the formative influence of a steppe
vegetation.
The one weak point of Richthofen’s theory is in the evident inadequacy
of the current disintegration as a source of material. When we
consider the immense area covered by loess to depths varying from 50
to 2,000 feet, and the fact that this is only the very finest portion
of the product of rock-destruction, and again that the accumulation
represents only a very short period of time, geologically speaking,
surely we must seek a more fertile source of supply than is furnished
by the current decomposition of rock surface.
It seems to me that there are two important sources: I. The silt
brought by rivers, many of them fed by the products of glacial
attrition flowing from the mountains into the central region. Where
the streams sink away, or where the lakes which receive them have
dried up, the finer products of the erosion of a large territory are
left to be removed in dust storms.
II. The second ... source is the residuary products of a secular
disintegration.”
The evidence presented by Pumpelly for the eolian origin of
loess—structure, texture, composition, fossil content and topographic
position—is complete, and to him belongs the credit for the correct
interpretation of the Mississippi valley deposits. Unfortunately his
contribution came at a time when the geologists of the central States
were intent on tracing the paths and explaining the work of Pleistocene
glaciers, and the belief was strong that loess was some phase of glacial
work. Its position at the border of the Iowan drift so obviously
suggests a genetic relation that the fossil evidence of steppe climate
suggested by Binney in 1848[69] was minimized. Students of Pleistocene
geology in Minnesota, Iowa, Nebraska, Missouri, although less vigorous
in expression, were substantially in agreement with Hilgard (1879).[70]
“The sum total of anomalous conditions required to sustain the eolian
hypothesis partakes strongly of the marvellous.” The last edition of
Dana’s Manual, 1894, and of LeConte’s Geology, 1896, the two most widely
used text-books of their time, oppose the eolian theory, and Chamberlin,
in 1897,[71] states: “the aqueous hypothesis seems best supported so far
as concerns the deposits of the Mississippi Valley and western Europe”
(p. 795). Shimek, in papers published since 1896 has shown that aquatic
and glacial conditions can not account for the loess fossils, and the
return to the views of Pumpelly that the loess was deposited on land by
the agency of wind in a region of steppe vegetation is now all but
universal.
_Glacial Sculpture._
Within the present generation sculpture by glaciers has received much
attention and has involved a reconsideration of the ability of ice to
erode which in turn involves a crystallization of views of the mechanics
of moving ice. The evidence for glacier erosion has remained largely
physiographic and rests on a study of land forms. In fact, the
inadequacy of structural features or of river corrasion to account for
flat-floored, steep-walled gorges, hanging valleys, and many lake
basins, rather than a knowledge of the mechanics of ice has led to the
present fairly general belief that glaciers are powerful agents of rock
sculpture. The details of the process are not yet understood.
Erosion by glaciers enters the arena of active discussion in 1862–63.
The possibility had been suggested by Esmark (1827) and by Dana (1849)
in the description of fiords and by Hind (1855) with reference to the
origin of the Great Lakes. It appears full-fledged in Ramsay’s classic,
which was published simultaneously in England and in America.[72] The
argument runs as follows: There is a close association of ancient
glaciers and lakes especially in mountains; glaciers are amply able to
erode; evidences of faulting, special subsidence, river erosion, and
marine erosion are absent from the lake basins of Switzerland and Great
Britain. To quote Ramsay:
“It required a solid body grinding steadily and powerfully in direct
and heavy contact with and across the rocks to scoop out deep hollows,
the situations of which might either be determined by unequal hardness
of the rocks, by extra weight of ice in special places, or by
accidental circumstances, the clue to which is lost from our inability
perfectly to reconstruct the original forms of the glaciers.”
“I believe with the Italian geologists, that all that the glaciers as
a whole effected was only slightly to deepen these valleys and
materially to modify their general outlines, and, further (a theory I
am alone responsible for), to deepen them in parts more considerably
when, from various causes, the grinding power of the ice was unusually
powerful, especially where, as in the lowlands of Switzerland, the
Miocene strata are comparatively soft.”
Whittlesey (1864)[73] considered that the rock-bound lakes and narrow
bays near Lake Superior were partly excavated by ice. LeConte (1875)[74]
records some significant observations in a pioneer paper on glacier
erosion which has not received adequate recognition. He says:
“... I am convinced that a glacier, by its enormous pressure and
resistless onward movement, is _constantly breaking off large blocks_
from its bed and bounding walls. Its erosion is not only a grinding
and scoring, but also a _crushing and breaking_. It makes by its
erosion not only rock-meal, but also large _rock-chips_.... Its
erosion is a constant process of alternate _rough hewing_ and
_planing_.
If Yosemite were unique, we might suppose that it was formed by
violent cataclysms; but _Yosemite is not unique_ in _form_ and
therefore probably not in _origin_. There are many Yosemites. It is
more philosophical to account for them by the _regular_ operation of
known causes. I must believe that all these deep perpendicular slots
have been sawn out by the action of glaciers; the _peculiar
verticality of the walls having been determined by the perpendicular
cleavage structure_.”... A lake in Bloody Canyon “is a _pure rock
basin scooped out by the glacier_ at this place.... These ridges
[separating Hope, Faith, and Charity valleys] are in fact the lips of
consecutive lake basins scooped out by ice.
... Water tends to form deep V-shaped canons, while ice produces broad
valleys with lakes and meadows.... I know not how general these
distinctions may be, but certainly the Coast range of this State is
characterized by rounded summits and ridges, and deep V-shaped canons,
while the high Sierras are characterized on the contrary by sharp,
spire-like, comb-like summits, and broad valleys; and this difference
I am convinced is due in part at least to the action of water on the
one hand, and of ice on the other.”
King (1878)[75] assigned to glacial erosion a commanding position in
mountain sculpture. In regard to the Uintas, he says:
“Glacial erosion has cut almost vertically down through the beds
carving immense amphitheatres with basin bottoms containing numerous
Alpine lakes.... Post-glacial erosion has done an absolutely trivial
work. There is not a particle of direct evidence, so far as I can see,
to warrant the belief that these U-shaped canons were given their
peculiar form by other means than the actual ploughing erosion of
glaciers....”
These contributions from the Cordilleras corroborating the conclusions
of Ramsay (1862), Tyndall (1862), Jukes (1862), Hector (1863), Logan
(1863), Close (1870), and James Geikie (1875), made little impression.
The views of Lyell (1833), Ball (1863), J. W. Dawson (1864), Falconer
(1864), Studer (1864), Murchison (1864, 1870), Ruskin (1865), Rutimeyer
(1869), Whymper (1871), Bonney (1873), Pfaff (1874), Gurlt (1874), Judd
(1876), prevailed, and the conclusions of Davis in 1882[76] fairly
expressed the prevailing belief in Europe and in America:
“The amount of glacial erosion in the central districts has been very
considerable, but not greatly in excess of pre-glacial soils and old
talus and alluvial deposits. Most of the solid rock that was carried
away came from ledges rather than from valleys; and glaciers had in
general a smoothing rather than a roughening effect. In the outer
areas on which the ice advanced it only rubbed down the projecting
points; here it acted more frequently as a depositing than as an
eroding agent.”
During the past quarter-century the cleavage in the ranks of geologists,
brought about by Ramsay’s classic paper, has remained. Fairchild and
others in America, Heim, Bonney, and Garwood in Europe argue for
insignificant erosion by glaciers; and Gannet, Davis, Gilbert, Tarr in
America followed by Austrian workers present evidence for erosion on a
gigantic scale. A perusal of the voluminous literature in the Journal
and elsewhere shows that the difference of opinion is in part one of
terms, the amount of erosion rather than the fact of erosion; it also
arises from failure to differentiate the work of mountain glaciers and
continental ice sheets, of Pleistocene glaciers and their present
diminished representatives. The irrelevant contribution of physicists
has also made for confusion.
It is interesting to note that the criteria for erosion of valleys by
glaciers has long been established and by workers in different
countries. Ramsay (1862) in England outlined the problem and presented
generalized evidence. Hector (1863) in New Zealand pointed out the
significance of discordant drainage, the “hanging valleys” of Gilbert.
The U-form, the broad lake-dotted floor, and the presence of cirques and
the process of plucking were probably first described by LeConte (1873)
in America. The truncation of valley spurs by glaciers pointed out by
Studer in the Kerguelen Islands (1878) was used by Chamberlin (1883) as
evidence of glacial scouring.
_Conclusion._
During the past century many principles of land sculpture have emerged
from the fog of intellectual speculation and unorganized observation and
taken their place among generally accepted truths. Many of them are no
longer subjects of controversy. Erosion has found its place as a major
geologic agent and has given a new conception of natural scenery. Lofty
mountains are no longer “ancient as the sun,” they are youthful features
in process of dissection; valleys and canyons are the work of streams
and glaciers; fiords are erosion forms; waterfalls and lakes are
features in process of elimination; many plains and plateaus owe their
form and position to long-continued denudation. Modern landscapes are no
longer viewed as original features or the product of a single agent
acting at a particular time, but as ephemeral forms which owe their
present appearance to their age and the particular forces at work upon
them as well as to their original structure.
It is interesting to note the halting steps leading to the present
viewpoint, to find that decades elapsed between the formulation of a
theory or the recording of significant facts and their final acceptance
or rejection, and to realize that the organization of principles and
observations into a science of physiography has been the work of the
present generation. Progress has been conditioned by a number of factors
besides the intellectual ability of individual workers.
The influence of locality is plainly seen. Convincing evidence of river
erosion was obtained in central France, the Pacific Islands, and the
Colorado Plateau—regions in which other causes were easily eliminated.
Sculpture by glaciers passed beyond the theoretical stage when the
simple forms of the Sierras and New Zealand Alps were described. The
origin of loess was first discerned in a region where glacial phenomena
did not obscure the vision. The complexity of the Glacial period
asserted by geologists of the Middle West was denied by eastern
students. The work of waves on the English coast impressed British
geologists to such an extent that plains of denudation and inland
valleys were ascribed to ocean work.
In the establishment of principles, the friendly interchange of ideas
has yielded large returns. Many of the fundamental conceptions of earth
sculpture have come from groups of men so situated as to facilitate
criticism. It is impossible, even if desirable, to award individual
credit to Venetz, Charpentier, and Agassiz in the formulation of the
glacial theory; and the close association of Agassiz and Dana in New
England and of Chamberlin and Irving in Wisconsin was undoubtedly
helpful in establishing the theory of continental glaciation. From the
intimate companionship in field and laboratory of Hutton, Playfair and
Hope, arose the profound influence of the Edinburgh school, and the
sympathetic cooperation of Powell, Gilbert, and Dutton has given to the
world its classics in the genetic study of land forms.
The influence of ideas has been closely associated with clarity,
conciseness, and attractiveness of presentation. Hutton is known through
Playfair, Agassiz’s contributions to glacial geology are known to every
student, while Venetz, Charpentier, and Hugi are only names. Cuvier’s
discourses on dynamical geology were reprinted and translated into
English and German, but Lamarck’s “Hydrogéologie” is known only to book
collectors. The verbose works of Guettard, although carrying the same
message as Playfair’s “Illustrations” and Desmarest’s “Memoirs,” are
practically unknown, as is also Horace H. Hayden’s treatise (1821) on
the drift of eastern North America. It has been well said that the
world-wide influence of American physiographic teaching is due in no
small part to the masterly presentations of Gilbert and Davis.
It is surprising to note the delays, the backward steps, and the
duplication of effort resulting from lack of familiarity with the work
of the pioneers. Sabine says in 1864:[77]
“It often happens, not unnaturally, that those who are most occupied
with the questions of the day in an advancing science retain but an
imperfect recollection of the obligations due to those who laid the
first foundations of our subsequent knowledge.”
The product of intellectual effort appears to be conditioned by time of
planting and character of soil as well as by quantity of seed. For
example: Erosion by rivers was as clearly shown by Desmarest as by Dana
and Newberry 50 years later. Criteria for the recognition of ancient
fluviatile deposits were established by James Deane in 1847 in a study
of the Connecticut Valley Triassic. Agassiz’s proof that ice is an
essential factor in the formation of till is substantially a duplication
of Dobson’s observations (1826).
The volumes of the Journal with their very large number of articles and
reviews dealing with geology show that the interpretation of land forms
as products of subaërial erosion began in France and French Switzerland
during the later part of the eighteenth century as a phase of the
intellectual emancipation following the Revolution. Scotland and England
assumed the leadership for the first half of the nineteenth century, and
the first 100 volumes of the Journal show the profound influence of
English and French teaching. In America, independent thinking, early
exercised by the few, became general with the establishment of the
Federal survey, the increase in university departments, geological
societies and periodicals, and has given to Americans the
responsibilities of teachers.
_Bibliography._
(In the following list “this Journal” refers to the American Journal of
Science.)
Footnote 4:
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Footnote 5:
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Footnote 6:
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Footnote 7:
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Footnote 8:
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Footnote 9:
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Footnote 10:
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Footnote 12:
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Footnote 13:
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Footnote 14:
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Footnote 15:
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Footnote 16:
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Footnote 18:
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Footnote 19:
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Footnote 17:
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Footnote 20:
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Footnote 21:
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Footnote 22:
Hayden, F. V., Some remarks in regard to the period of elevation of
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Footnote 23:
Newberry, J. S., Colorado River of the West, this Journal, =33=,
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Footnote 24:
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Footnote 25:
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Footnote 26:
McGee, W. J., Three formations of the Middle Atlantic slope, this
Journal, =35=, 120, 328, 367, 448, 1888.
Footnote 27:
Davis, W. M., Topographic development of the Triassic formation of the
Connecticut Valley, this Journal, =37=, 423–434, 1889.
Footnote 28:
Percival, J. G., Geology of Connecticut, 1842.
Footnote 29:
Kerr, W. C., Origin of some new points in the topography of North
Carolina, this Journal, =21=, 216–219, 1881.
Footnote 30:
McGee, W. J., The classification of geographic forms by genesis, Nat.
Geogr. Mag., =1=, 27–36, 1888.
Footnote 31:
Davis, W. M., The rivers and valleys of Pennsylvania, Nat. Geogr.
Mag., =1=, 183–253, 1889.
——, The rivers of northern New Jersey with notes on the classification
of rivers in general, ibid., =2=, 81–110, 1890.
Footnote 32:
Silliman, Benjamin, Notice of Horace H. Hayden’s geological essays,
this Journal, =3=, 49, 1821.
Footnote 33:
Cornelius, Elias, Account of a singular position of a granite rock,
this Journal, =2=, 200–201, 1820.
Footnote 34:
Finch, John, On the Celtic antiquities of America, this Journal, =7=,
149–161, 1824.
Footnote 35:
Finch, John, Geological essay on the Tertiary formations in America,
this Journal, =7=, 31–43, 1824.
Footnote 36:
Conybeare and Phillips, Outlines of the geology of England and Wales,
this Journal, =7=, 210, 211, 1824.
Footnote 37:
Hayden, Horace H., Geological essays, 1–412, 1821, this Journal, =3=,
47–57, 1821.
Footnote 38:
Jackson, C. T., Reports on the geology of the State of Maine, and on
the public lands belonging to Maine and Massachusetts, this Journal,
=36=, 153, 1839.
Footnote 39:
Gibson, J. B., Remarks on the geology of the lakes and the valley of
the Mississippi, this Journal, =29=, 201–213, 1836.
Footnote 40:
Phillips, John, Geology of Yorkshire, this Journal, =21=, 14–15, 1832.
Footnote 41:
Granger, Ebenezer, Notice of a curious fluted rock at Sandusky Bay,
Ohio, this Journal, =6=, 180, 1823.
Footnote 42:
Dobson, Peter, Remarks on bowlders, this Journal, =10=, 217–218, 1826.
Footnote 43:
Murchison, R. I., Address at anniversary meeting of the Geological
Society of London, this Journal, =43=, 200–201, 1842.
Footnote 44:
Peter Dobson (1784–1878) came to this country from Preston, England,
in 1809 and established a cotton factory at Vernon, Conn.
Footnote 45:
Buckland, W., On the evidence of glaciers in Scotland and the north of
England, Proc. London Geol. Soc., =3=, 1841.
Footnote 46:
Hitchcock, Edward, First anniversary address before the Association of
American Geologists, this Journal, =41=, 232–275, 1841.
Footnote 47:
Third annual meeting of the Association of American Geologists and
Naturalists, this Journal, =43=, 154, 1842; Abstract of proceedings of
the fourth session of the Association of American Geologists and
Naturalists, ibid., =45=, 321, 1843.
Footnote 48:
Rogers, H. D., Address delivered before Association of American
Geologists and Naturalists, this Journal, =47=, 275, 1844.
Footnote 49:
Agassiz, Louis, The erratic phenomena about Lake Superior, this
Journal, =10=, 83–101, 1850.
Footnote 50:
Desor, E., On the drift of Lake Superior, this Journal, 13, 93–109,
1852; Post-Pliocene of the southern States, etc., =14=, 49–59, 1852.
Footnote 51:
Dana, J. D., Manual of geology, 546, Philadelphia, 1863.
Footnote 52:
Dana, J. D., on the Quaternary, or post-Tertiary of the New Haven
region, this Journal, =1=, 1–5, 1871.
Footnote 53:
Matthew, G. F., Surface geology of New Brunswick, this Journal, =2=,
371–372, 1871.
Footnote 54:
Maclaren, Charles, The glacial theory of Prof. Agassiz, this Journal,
=42=, 365, 1842.
Footnote 55:
Daly, R. A., Problems of the Pacific Islands, this Journal, =41=,
153–186, 1916.
Footnote 56:
Catlin, George, Account of a journey to the Côteau des Prairies, this
Journal, =38=, 138–146, 1840.
Footnote 57:
Hilgard, E. W., Remarks on the drift of the western and southern
States and its relation to the glacier and iceberg theories, this
Journal, =42=, 343–347, 1866.
Footnote 58:
Hall, C. E., Glacial phenomena along the Kittatinny or Blue Mountain,
Pennsylvania, this Journal, =11=, review, 233, 1876.
Footnote 59:
Stevens, R. P., On glaciers of the glacial era in Virginia, this
Journal, =6=, 371–373, 1873.
Footnote 60:
Rogers, W. B., On the gravel and cobble-stone deposits of Virginia and
the Middle States, Proc. Boston Soc. Nat. Hist., 18, 1875; this
Journal, =11=, 60–61, 1876.
Footnote 61:
Kerr, W. C, Origin of some new points in the topography of North
Carolina, this Journal, =21=, 216–219, 1881.
Footnote 62:
Gilbert, G. K., On certain glacial and post-glacial phenomena of the
Maumee valley, this Journal, =1=, 339–345, 1871.
Footnote 63:
Chamberlin, T. C., On the geology of eastern Wisconsin, Geol. of
Wisconsin, =2=, 1877; this Journal, 15, 61, 406, 1878.
Footnote 64:
Chamberlin, T. C, Preliminary paper on the terminal moraine of the
second glacial epoch, U. S. Geol. Survey, Third Ann. Rept., 291–402,
1883.
Footnote 65:
Wright, G. F., Unity of the glacial epoch, this Journal, =44=,
351–373, 1892.
Upham, Warren, The diversity of the glacial drift along its boundary,
ibid., =47=, 358–365, 1894.
Wright, G. F., Theory of an interglacial submergence in England,
ibid., =43=, 1–8, 1892.
Chamberlin, T. C., Diversity of the glacial period, ibid., =45=,
171–200, 1983
Dana, J. D., On New England and the upper Mississippi basin in the
glacial period, ibid., =46=, 327–330, 1893.
Wright, G. F., Continuity of the glacial period, ibid., =47=, 161–187,
1894.
Chamberlin, T. C. and Leverett, F., Further studies of the drainage
features of the upper Ohio basin, ibid., =47=, 247–282, 1894.
Footnote 66:
Pumpelly, Raphael, Geological researches in China, Japan, and
Mongolia, Smithsonian Contributions, No. 202, 1866.
Footnote 67:
Kingsmill, T. W., The probable origin of “loess” in North China and
eastern Asia, Quart. Jour. Geol. Soc., =27=, No. 108, 1871.
Footnote 68:
Pumpelly, Raphael, The relation of secular rock-disintegration to
loess, glacial drift and rock basins, this Journal, =17=, 135, 1879.
Footnote 69:
Binney, A., Some geologic features at Natchez on the Mississippi
River, Proc. Boston Soc. Nat. Hist., =2=, 126–130, 1848.
Footnote 70:
Hilgard, E. W., The loess of Mississippi Valley, and the eolian
hypothesis, this Journal, =18=, 106–112, 1879.
Footnote 71:
Chamberlin, T. C, Supplementary hypothesis respecting the origin of
the loess of the Mississippi Valley, Jour. Geol., =5=, 795–802, 1897.
Footnote 72:
Ramsay, A. C., On the glacial origin of certain lakes in Switzerland,
the Black Forest, Great Britain, Sweden, North America, and elsewhere,
Quart. Jour. Geol. Soc., 1862; this Journal, =35=, 324–345, 1863.
Preliminary statements of this theory appeared in 1859 and 1860.
Footnote 73:
Whittlesey, Charles, Smithsonian Contributions, No. 197, 1864.
Footnote 74:
LeConte, Joseph, On some of the ancient glaciers of the Sierras, this
Journal, =5=, 325–342, 1873, 10, 126–139, 1875.
Footnote 75:
King, Clarence, U. S. Geol. Expl. 40th Par., 1, 459–529, 1878.
Footnote 76:
Davis, W. M., Glacial erosion, Proc. Boston Soc. Nat. Hist., =22=,
=58=, 1882.
Footnote 77:
Sabine, Sir Edward, Address of the president of the Royal Society,
this Journal, =37=, 108, 1864.
IV
A CENTURY OF GEOLOGY.—THE GROWTH OF KNOWLEDGE OF EARTH STRUCTURE