demonstrated that the system also abounds in Ordovician fossiliferous
formations. Then came the far-reaching work of Charles D. Walcott,
beginning in 1886, which showed that all through eastern New York and
into northern Vermont the Hudson River group and the Taconic system
abound not only in Ordovician but also in Cambrian fossils. Finally in
1888 Dana presented a Brief History of Taconic Ideas, and laid away the
system with these words (=36=, 27):
“It is almost fifty years since the Taconic system made its abrupt
entrance into geological science. Notwithstanding some good points, it
has been through its greater errors, long a hindrance to progress here
and abroad ... But, whether the evil or the good has predominated, we
may now hope, while heartily honoring Professor Emmons for his earnest
geological labors and his discoveries, that Taconic ideas may be
allowed to be and remain part of the past.”
As an epitaph Dana placed over the remains of the Taconic system the
black-faced numerals =1841–1888=. That the remains of the system,
however, and the term Taconic are still alive and demanding a rehearing
is apparent to all interested stratigraphers. This is not the place to
set the matter right, and all that can be done at the present time is to
point out what are the things that still keep alive Emmons’s system.
In the typical area of the Taconic system, i. e., in Rensselaer County,
Emmons in 1844–1846 produced the fossils _Atops trilineatus_ and
_Elliptocephala asaphoides_. S. W. Ford, as stated above, later produced
from the same general area many other fossils that he demonstrated to be
older than the Potsdam sandstone. To this time he gave the name of Lower
Potsdam, thus proving on paleontological grounds that at least some part
of the Taconic system is older than the New York system, and therefore
older than the Hudson River group of Ordovician age.
In 1888 Walcott presented his conclusions in regard to the sequence of
the strata in the typical Taconic area and to the north and south of it.
He collected Lower Cambrian fossils at more than one hundred localities
“within the typical Taconic area,” and said that the thickness of his
“terrane No. 5” or “Cambrian (Georgia),” now referable to the Lower
Cambrian, is “14,000 feet or more.” He demonstrated that the Lower
Cambrian is infolded with the Lower and Middle Ordovician, and confirmed
Emmons’s statement that the former rests upon his Primary or
Pre-Cambrian masses. Elsewhere, he writes: “To the west of the Taconic
range the section passes down through the limestone (3) [of Lower and
Middle Ordovician age] to the hydromica schists (2) [whose age may also
be of early Ordovician], and thence to the great development of slates
and shales with their interbedded sparry limestones, calciferous and
arenaceous strata, all of which contain more or less of the
Olenellus ... fauna.” He then knew thirty-five species in Washington
County, New York (=35=, 401, 1888).
Finally in 1915 Walcott said that in the Cordilleran area of America
there was a movement that brought about changes “in the sedimentation
and succession of the faunas which serve to draw a boundary line between
the Lower and Middle Cambrian series.... The length of this period of
interruption must have been considerable ... and when connection with
the Pacific was resumed a new fauna that had been developing in the
Pacific was then introduced into the Cordilleran sea and constituted the
Middle Cambrian fauna. The change in the species from the Lower to the
Middle Cambrian fauna is very great.” He then goes on to show that in
the Appalachian geosyncline there was another movement that shut out the
Middle Cambrian _Paradoxides_ fauna of the Atlantic realm from this
trough, and all deposition as well.
_Conclusions._—Accordingly it appears that everywhere in America the
Lower Cambrian formations are separated by a land interval of long
duration from those of Middle Cambrian time. These formations therefore
unite into a natural system of rocks or a period of time. Between Middle
and Upper Cambrian time, however, there appears to be a complete
transition in the Cordilleran trough, binding these two series of
deposits into one natural or diastrophic system. Hence the writer
proposes that the Lower Cambrian of America be known as the Taconic
system. The Middle and Upper Cambrian series can be continued for the
present under the term Cambrian system, a term, however, that is by no
means in good standing for these formations, as will be demonstrated
under the discussion of the Silurian controversy.
_The Silurian Controversy._
Just as in America the base of the Paleozoic was involved in a
protracted controversy, so in England the Cambrian-Silurian succession
was a subject of long debate between Sedgwick and Murchison, and among
the succeeding geologists of Europe. The history of the solution is so
well and justly stated in the Journal by James D. Dana under the title
“Sedgwick and Murchison: Cambrian and Silurian” (=39=, 167, 1890), and
by Sir Archibald Geikie in his Text-book of Geology, 1903, that all that
is here required is to briefly restate it and to bring the solution up
to date.
Adam Sedgwick (1785–1873) and R. I. Murchison (1792–1871) each began to
work in the areas of Cambria (Wales) and Siluria (England) in 1831, but
the terms Cambrian and Silurian were not published until 1835. Murchison
was the first to satisfactorily work out the sequence of the Silurian
system because of the simpler structural and more fossiliferous
condition of his area. Sedgwick, on the other hand, had his academic
duties to perform at Cambridge University, and being an older and more
conservative man, delayed publishing his final results, because of the
further fact that his area was far more deformed and less fossiliferous.
In 1834 they were working in concert in the Silurian area, and Sedgwick
said: “I was so struck by the clearness of the natural sections and the
perfection of his workmanship that I received, I might say, with
implicit faith everything which he then taught me.... The whole
‘Silurian system’ was by its author placed _above_ the great undulating
slate-rocks of South Wales.” At that time Murchison told Sedgwick that
the Bala group of the latter, now known to be in the middle of the Lower
Silurian, could not be brought within the limits of the Silurian system,
and added, “I believe it to plunge under the true Llandeilo-flags,” now
placed next below the Bala and above the Arenig, which at the present is
regarded as at the base of the Ordovician.
The Silurian system was defined in print by Murchison in July, 1835, the
Upper Silurian embracing the Ludlow and Wenlock, while the Lower
Silurian was based on the Caradoc and Llandeilo. Murchison’s monumental
work, The Silurian System, of 100 pages and many plates of fossils,
appeared in 1838.
The Cambrian system was described for the first time by Sedgwick in
August, 1835, but the completed work—a classic in geology—Synopsis of
the Classification of the British Palæozoic Rocks, along with M’Coy’s
Descriptions of British Palæozoic Fossils, did not appear until
1852–1855. Sedgwick’s original Upper Cambrian included the greater part
of the chain of the Berwyns, where he said it was connected with the
Llandeilo flags of the Silurian. The Middle Cambrian comprised the
higher mountains of Cærnarvonshire and Merionethshire, and the Lower
Cambrian was said to occupy the southwest coast of Cærnarvonshire, and
to consist of chlorite and mica schists, and some serpentine and
granular limestone. In 1853 it was seen that the fossiliferous Upper
Cambrian included the Arenig, Llandeilo, Bala, Caradoc, Coniston,
Hirnant, and Lower Llandovery. On the other hand, it was not until long
after Murchison and Sedgwick passed away that the Middle and Lower
Cambrian were shown to have fossils, but few of those that characterize
what is now called Lower, Middle, and Upper Cambrian time.
Not until long after the original announcement of the Cambrian system
did Sedgwick become aware “of the unfortunate mischief-involving fact”
that the most fossiliferous portion of the Cambrian—the Upper
Cambrian—and at that time the only part yielding determinable fossils,
when compared with the Lower Silurian was seen to be an equivalent
formation but with very different lithologic conditions. He began to see
in 1842 that his Cambrian was in conflict with the Silurian system, and
four years later there were serious divergencies of views between
himself and Murchison. The climax of the controversy was attained in
1852, when Sedgwick was extending his Cambrian system upwards to include
the Bala, Llandeilo, and Caradoc, a proceeding not unlike that of
Murchison, who earlier had been extending his Silurian downward through
all of the fossiliferous Cambrian to the base of the Lingula flags.
Dana in his review of the Silurian-Cambrian controversy states: “The
claim of a worker to affix a name to a series of rocks first studied and
defined by him cannot be disputed.” We have seen that Murchison had
priority of publication in his term Silurian over Sedgwick’s Cambrian,
but that in a complete presentation, both stratigraphically and
faunally, the former had years of prior definition. What has even more
weight is that geologists nearly everywhere had accepted Murchison’s
Silurian system as founded upon the Lower and Upper Silurian formations.
A nomenclature once widely accepted is almost impossible to dislodge.
However, in regard to the controversy it should not be forgotten that it
was only Murchison’s _Lower_ Silurian that was in conflict with
Sedgwick’s _Upper_ Cambrian. As for the rest of the Cambrian, that was
not involved in the controversy.
Dana goes on to state that science may accept a name, or not, according
as it is, or is not, needed. In the progress of geology, he thought that
the time had finally been reached when the name Cambrian was a
necessity, and he included both Cambrian and Silurian in the geological
record. The “Silurian,” however, included the Lower and Upper
Silurian—not one system of rocks, but two.
It is now twenty-seven years since Dana came to this conclusion, at a
time when it was believed that there was more or less continuous
deposition not only between the formations of a system but between the
systems themselves as well. To-day many geologists hold that in the
course of time the oceans pulsate back and forth over the continents,
and accordingly that the sequence of marine sedimentation in most places
must be much broken, and to-day we know that the breaks or land
intervals in the marine record are most marked between the eras, and
shorter between all or at least most of the periods. Furthermore, in
North America, we have learned that the breaks between the systems are
most marked in the interior of the continent and less so on or toward
its margins.
Hardly any one now questions the fact of a long land interval between
the Lower Silurian and Upper Silurian in England, and it is to
Sedgwick’s credit that he was the first to point out this fact and also
the presence of an unconformity. It therefore follows that we cannot
continue to use Silurian system in the sense proposed by Murchison,
since it includes two distinct systems or periods. Dana, in the last
edition of his Manual of Geology (1895), also recognizes two systems,
but curiously he saw nothing incongruous in calling them “Lower Silurian
era” and “Upper Silurian era.” It certainly is not conducive to clear
thinking, however, to refer to two systems by the one name of Silurian
and to speak of them individually as Lower and Upper Silurian, thus
giving the impression that the two systems are but parts of one—the
Silurian. Each one of the parts has its independent faunal and physical
characters.
We must digress a little here and note the work of Joachim Barrande
(1799–1883) in Bohemia. In 1846 he published a short account of the
“Silurian system” of Bohemia, dividing it into étages lettered C to H.
Between 1852 and 1883 he issued his “Système Silurien du Centre de la
Bohème,” in eighteen quarto volumes with 5568 pages of text and 798
plates of fossils—a monumental work unrivalled in paleontology. In the
first volume the geology of Bohemia is set forth, and here we see that
étages A and B are Azoic or pre-Cambrian, and C to H make up his
Silurian system. Etage C has his “Primordial fauna,” now known to be of
Paradoxides or Middle Cambrian time, while D is Lower Silurian, E is
Upper Silurian, F is Lower Devonian, and G and H are Middle Devonian.
From this it appears that Barrande’s Silurian system is far more
extensive than that of Murchison, embracing twice as many periods as
that of England and Wales.
About 1879 there was in England a nearly general agreement that Cambrian
should embrace Barrande’s Primordial or Paradoxides faunas, and in the
North Wales area be continued up to the top of the Tremadoc slates.
To-day we would include Middle and Upper Cambrian. Lower Cambrian in the
sense of containing the Olenellus faunas was then unknown in Great
Britain.
Lapworth, recognizing the distinctness of the Lower Silurian as a
system, proposed in 1879 to recognize it as such, and named it
Ordovician, restricting Silurian to Murchison’s Upper Silurian. This
term has not been widely used either in Great Britain or on the
Continent, but in the last twenty years has been accepted more and more
widely in America. Even here, however, it is in direct conflict with the
term Champlain, proposed by the New York State Geologist in 1842.
In 1897 the International Geological Congress published E. Renevier’s
Chronographie Géologique, wherein we find the following:
│Upper or Silurian │Ludlowian (Murchison
Silurian Period. │ (Murchison, restricted, │ 1839).
│ 1835). │
„ │ „ │Wenlockian (Murchison
│ │ 1839).
„ │ „ │Landoverian (Murchison).
─────────────────┼──────────────────────────┼──────────────────────────
„ │Middle or Ordovician │Caradocian (Murchison
│ (Lapworth 1879). │ 1839).
„ │ „ │Landeilian (Murchison
│ │ 1839).
„ │ „ │Arenigian (Sedgwick 1847).
─────────────────┼──────────────────────────┼──────────────────────────
│Lower or Cambrian │
„ │ (Sedgwick, restricted, │Potsdamian (Emmons 1838).
│ 1835). │
„ │ „ │Menevian (Salter and Hicks
│ │ 1865).
„ │ „ │Georgian (Hitchcock 1861).
Regarding this period, which, by the way, is not very unlike that of
Barrande, Renevier remarks that it is “as important as the Cretaceous or
the Jurassic. Lapworth even gives it a value of the first order equal to
the Protozoic era.”
In the above there is an obvious objection in the double usage of the
term Silurian, and this difficulty was met later on in Lapparent’s
Traité by the proposal to substitute Gothlandian for Silurian. Of this
change Geikie remarks: “Such an arrangement ... might be adopted if it
did not involve so serious an alteration of the nomenclature in general
use.” On the other hand, if diastrophism and breaks in the stratigraphic
and faunal sequence are to be the basis for geologic time divisions, we
cannot accept the above scheme, for it recognizes but one period where
there are at least four in nature.
_Conclusions._—We have arrived at a time when our knowledge of the
stratigraphic and faunal sequence, plus the orogenic record as
recognized in the principle of diastrophism, should be reflected in the
terminology of the geologic time-table. It would be easy to offer a
satisfactory nomenclature if we were not bound by the law of priority in
publication, and if no one had the geologic chronology of his own time
ingrained in his memory. In addition, the endless literature, with its
accepted nomenclature, bars our way. Therefore with a view of creating
the least change in geologic nomenclature, and of doing the greatest
justice to our predecessors that the present conditions of our knowledge
will allow, the following scheme is offered:
Silurian period. Llandovery to top of Ludlow in Europe.
Alexandrian-Cataract-Medina to top of Manlius in America.
Champlain (1842) or Ordovician (1879) period. Arenig to top of Caradoc
in Europe. Beekmantown to top of Richmondian in America.
Cambrian period. In the Atlantic realm, begins with the Paradoxides,
and in the Pacific, with the Bathyuriscus and Ogygopsis faunas. The
close is involved in Ulrich’s provisionally defined Ozarkian system.
When the latter is established, the Ozarkian period will hold the time
between the Ordovician and the Cambrian.
Taconic period. For the world-wide Olenellus or Mesonacidæ faunas.
_Paleogeography._
When geologists began to perceive the vast significance of Hutton’s
doctrine that “the ruins of an earlier world lie beneath the secondary
strata,” and that great masses of bedded rocks are separated from one
another by periods of mountain making and by erosion intervals, it was
natural for them to look for the lands that had furnished the debris of
the accumulated sediments. In this way paleogeography had its origin,
but it was at first of a descriptive and not of a cartographic nature.
The word paleogeography was proposed by T. Sterry Hunt in 1872 in a
paper entitled “The Paleogeography of the North American Continent,” and
published in the Journal of the American Geographical Society for that
year. It has to do, he says, with the “geographical history of these
ancient geological periods.” It was again prominently used by Robert
Etheridge in his presidential address before the Geological Society of
London in 1881. Since Canu’s use of the term in 1896, it has been
frequently seen in print, and now is generally adopted to signify the
geography of geologic time.
The French were the first to make paleogeographic maps, and Jules Marcou
relates in 1866 that Elie de Beaumont, as early as March, 1831, in his
course in the College of France and at the Paris School of Mines, used
to outline the relation of the lands and the seas in the center of
Europe at the different great geologic periods. His first printed
paleogeographic map appeared in 1833, and was of early Tertiary time.
Other maps by Beaumont were published by Beudant in 1841–1842. The
Sicilian geologist Gemmellaro published six maps of his country in 1834,
and the Englishman De La Beche had one in the same year. In America the
first to show such maps was Arnold Guyot in his Lowell lectures of 1848.
James D. Dana published three in the 1863 edition of his Manual of
Geology. Of world paleogeographic maps, Jules Marcou produced the first
of Jurassic time, publishing it in France in 1866, but the most
celebrated of these early attempts was the one by Neumayr published in
1883 in connection with his Ueber klimatische Zonen während der Jura-
und Kreidezeit.
The first geologist to produce a series of maps showing the progressive
geologic geography of a given area was Jukes-Brown, who in the volume
entitled “The Building of the British Isles,” 1888, included fifteen
such maps. Karpinsky published fourteen maps of Russia, and in 1896 Canu
in his Essai de paléogéographie has fifty-seven of France and Belgium.
Lapparent’s Traité of 1906 is famous for paleogeographic maps, for he
has twenty-three of the world, thirty-four of Europe, twenty-five of
France, and ten taken from other authors. Schuchert in 1910 published
fifty-two to illustrate the paleogeography of North America, and also
gave an extended list of such published maps. Another article on the
subject is by Th. Arldt, “Zur Geschichte der Paläogeographischen
Rekonstructionen,” published in 1914. Edgar Dacqué in 1913 also produced
a list in his Paläogeographischen Karten, and two years later appeared
his book of 500 pages, Grundlagen und Methoden der Paläogeographie,
where the entire subject is taken up in detail.
_Conclusions._—Since 1833 there have been published not less than 500
different paleogeographic maps, and of this number about 210 relate to
North America. Nevertheless paleogeography is still in its infancy, and
most maps embrace too much geologic time, all of them tens of thousands,
and some of them millions of years. The geographic maps of the present
show the conditions of the strand-lines of to-day, and those made fifty
years ago have to be revised again and again if they are to be of value
to the mariner and merchant. Therefore in our future paleogeographic
maps the tendency must ever be toward smaller amounts of geologic time,
if we are to show the actual relation of water to land and the movements
of the periodic floodings. Moreover, the ancient shore lines are all
more or less hypothetic and are drawn in straight or sweeping curves,
unlike modern strands with their bays, deltas, and headlands, and the
ancient lands are featureless plains. We must also pay more attention to
the distribution of brackish- and fresh-water deposits. The periodically
rising mountains will be the first topographic features to be shown upon
the ancient lands, and then more and more of the drainage and the
general climatic conditions must be portrayed. In the seas, depth,
temperature, and currents are yet to be deciphered. Finally, other base
maps than those of the geography of to-day will have to be made,
allowing for the compression of the mountainous areas, if we are to show
the true geographic configurations of the lands and seas of any given
geologic time.
_Paleometeorology._
In accordance with the Laplacian theory, announced at the beginning of
the nineteenth century, all of the older geologists held that the earth
began as a hot star, and that in the course of time it slowly cooled and
finally attained its present zonal cold to tropical climatic conditions.
That the earth had very recently passed through a much colder climate, a
glacial one, came into general acceptance only during the latter half of
the previous century.
_Rise._—Our knowledge of glacial climates had its origin in the Alps,
that wonderland of mountains and glaciers. The rise of this knowledge in
the Alps is told in a charming and detailed manner by that erratic
French-American geologist, Jules Marcou (1824–1898), in his Life,
Letters, and Works of Louis Agassiz, 1896. He relates that the Alpine
chamois hunter Perraudin in 1815 directed the attention of the engineer
De Charpentier to the fact “that the large boulders perched on the sides
of the Alpine valleys were carried and left there by glaciers.” For a
long time the latter thought the conclusion extravagant, and in the
meantime Perraudin told the same thing to another engineer, Venetz. He,
in 1829, convinced of the correctness of the chamois hunter’s views,
presented the matter before the Swiss naturalists then meeting at St.
Bernard’s. Venetz “told the Society that his observations led him to
believe that the whole Valais has been formerly covered by an immense
glacier and that it even extended outside of the canton, covering all
the Canton de Vaud, as far as the Jura Mountains, carrying the boulders
and erratic materials, which are now scattered all over the large Swiss
valley.” Eight years earlier, in 1821, similar views had been presented
by the same modest naturalist before the Helvetic Society, but it was
not until 1833 that De Charpentier found the manuscript and had it
published. Venetz’s conclusions were that all of the glaciers of the
Bagnes valley “have very recognizable moraines, which are about a league
from the present ice.” “The moraines ... date from an epoch which is
lost in the night of time.” Then in 1834 De Charpentier read a paper
before the same society, meeting at Lucerne. “Seldom, if ever, has such
a small memoir so deeply excited the scientific world. It was received
at first with incredulity and even scorn and mockery, Agassiz being
among its opponents.” The paper was published in 1835, first at Paris,
then at Geneva, and finally in Germany. It “attracted much attention,
and the smile of incredulity with which it was received when read at
Lucerne soon changed into a desire to know more about it.”
Louis Agassiz (1807–1873), who had long been acquainted with his
countryman, De Charpentier, spent several months with him in 1836, and
together they studied the glaciers of the Alps. Agassiz was at first
“adverse to the hypothesis, and did not believe in the great extension
of glaciers and their transportation of boulders, but on the contrary,
was a partisan of Lyell’s theory of transport by icebergs and
ice-cakes ... but from being an adversary of the glacial theory, he
returned to Neuchâtel an enthusiastic convert to the views of Venetz and
De Charpentier.... With his power of quick perception, his unmatched
memory, his perspicacity and acuteness, his way of classifying, judging
and marshalling facts, Agassiz promptly learned the whole mass of
irresistible arguments collected patiently during seven years by De
Charpentier and Venetz, and with his insatiable appetite and that
faculty of assimilation which he possessed in such a wonderful degree,
he digested the whole doctrine of the glaciers in a few weeks.”
In July, 1837, Agassiz presented as his presidential address before the
Helvetic Society his memorable “Discours de Neuchâtel,” which was “the
starting point of all that has been written on the Ice-age,”—a term
coined at the time by his friend Schimper, a botanist. The first part of
this address is reprinted in French in Marcou’s book on Agassiz. The
address was received with astonishment, much incredulity, and
indifference. Among the listeners was the great German geologist Von
Buch, who “was horrified, and with his hands raised towards the sky, and
his head bowed to the distant Bernese Alps, exclaimed: ‘O Sancte de
Saussure, ora pro nobis!’” Even De Charpentier “was not gratified to see
his glacial theory mixed with rather uncalled for biological problems,
the connection of which with the glacial age was more than problematic.”
Agassiz was then a Cuvierian catastrophist and creationist, and advanced
the idea of a series of glacial ages to explain the destruction of the
geologic succession of faunas! Curiously, this theory was at once
accepted by the American paleontologist T. A. Conrad (=35=, 239, 1839).
The classics in glacial geology are Agassiz’s Etudes sur les Glaciers,
1840, and De Charpentier’s Essai sur les Glaciers, 1841. Of the latter
book, Marcou states that it has been said: “It is impossible to be truly
a geologist without having read and studied it.” In the English language
there is Tyndall’s Glaciers of the Alps, 1860.
The progress of the ideas in regard to Pleistocene glaciation is
presented in the following chapter by H. E. Gregory.
_Older Glacial Climates._—Hardly had the Pleistocene glacial climate
been proved, when geologists began to point out the possibility of even
earlier ones. An enthusiastic Scotch writer, Sir Andrew Ramsay, in 1855
described certain late Paleozoic conglomerates of middle England, which
he said were of glacial origin, but his evidence, though never
completely gainsaid, has not been generally accepted. In the following
year, an Englishman, Doctor W. T. Blanford, said that the Talchir
conglomerates of central and southern India were of glacial origin, and
since then the evidence for a Permian glacial climate has been steadily
accumulating. Africa is the land of tillites, and here in 1870
Sutherland pointed out that the conglomerates of the Karroo formation
were of glacial origin. Australia also has Permian glacial deposits, and
they are known widely in eastern Brazil, the Falkland Islands, the
vicinity of Boston, and elsewhere. So convincing is this testimony that
all geologists are now ready to accept the conclusion that a glacial
climate was as wide-spread in early Permian time as was that of the
Pleistocene.[3]
In South Africa, beneath the marine Lower Devonian, occurs the Table
Mountain series, 5000 feet thick. The series is essentially one of
quartzites, with zones of shales or slates and with striated pebbles up
to 15 inches long. The latter occur in pockets and seem to be of glacial
origin. There are here no typical tillites, and no striated undergrounds
have so far been found. While the evidence of the deposits appears to
favor the conclusion that the Table Mountain strata were laid down in
cold waters with floating ice derived from glaciers, it is as yet
impossible to assign these sediments a definite geologic age. They are
certainly not younger than the Lower Devonian, but it has not yet been
established to what period of the early Paleozoic they belong.
In southeastern Australia occur tillites of wide distribution that lie
conformably beneath, but sharply separated from the fossiliferous marine
Lower Cambrian strata. David (1907), Howchin (1908), and other
Australian geologists think they are of Cambrian time, but to the writer
they seem more probably late Proterozoic in age. In arctic Norway Reusch
discovered unmistakable tillites in 1891, and this occurrence was
confirmed by Strahan in 1897. It is not yet certainly known what their
age is, but it appears to be late Proterozoic rather than early
Paleozoic. Other undated Proterozoic tillites occur in China (Willis and
Blackwelder 1907), Africa (Schwarz 1906), India (Vredenburg 1907),
Canada (Coleman 1908), and possibly in Scotland.
The oldest known tillites are described by Coleman in 1907, and occur at
the base of the Lower Huronian or in early Proterozoic time. They extend
across northern Ontario for 1000 miles, and from the north shore of Lake
Huron northward for 750 miles.
_Fossils as Climatic Indexes._—Paleontologists have long been aware that
variations in the climates of the past are indicated by the fossils, and
Neumayr in 1883 brought the evidence together in his study of climatic
zones mentioned elsewhere. Plants, and corals, cephalopods, and
foraminifers among marine animals, have long been recognized as
particularly good “life thermometers.” In fact, all fossils are climatic
indicators to some extent, and a good deal of evidence concerning
paleometeorology has been discerned in them. This evidence is briefly
stated in the paper by Schuchert already alluded to, and in W. D.
Matthew’s Climate and Evolution, 1915.
_Sediments as Climatic Indexes._—Johannes Walther in the third part of
his Einleitung—Lithogenesis der Gegenwart, 1894—is the first one to
decidedly direct attention to the fact that the sediments also have
within themselves a climatic record. In America Joseph Barrell has since
1907 written much on the same subject. On the other hand, the periodic
floodings of the continents by the oceans, and the making of mountains,
due to the periodic shrinkage of the earth, as expressed in T. C.
Chamberlin’s principle of diastrophism and in his publications since
1897, are other criteria for estimating the climates of the past.
_Conclusions._—In summation of this subject Schuchert says:
“The marine ‘life thermometer’ indicates vast stretches of time of
mild to warm and equable temperatures, with but slight zonal
differences between the equator and the poles. The great bulk of
marine fossils are those of the shallow seas, and the evolutionary
changes recorded in these ‘medals of creation’ are slight throughout
vast lengths of time that are punctuated by short but decisive periods
of cooled waters and great mortality, followed by quick evolution, and
the rise of new stocks. The times of less warmth are the _miotherm_
and those of greater heat the _pliotherm_ periods of Ramsay.
On the land the story of the climatic changes is different, but in
general the equability of the temperature simulates that of the
oceanic areas. In other words, the lands also had long-enduring times
of mild to warm climates. Into the problem of land climates, however,
enter other factors that are absent in the oceanic regions, and these
have great influence upon the climates of the continents. Most
important of these is the periodic warm-water inundation of the
continents by the oceans, causing insular climates that are milder and
moister. With the vanishing of the floods somewhat cooler and
certainly drier climates are produced. The effects of these periodic
floods must not be underestimated, for the North American continent
was variably submerged at least seventeen times, and over an area of
from 154,000 to 4,000,000 square miles.
When to these factors is added the effect upon the climate caused by
the periodic rising of mountain chains, it is at once apparent that
the lands must have had constantly varying climates. In general the
temperature fluctuations seem to have been slight, but geographically
the climates varied between mild to warm pluvial, and mild to cool
arid. The arid factor has been of the greatest import to the organic
world of the lands. Further, when to all of these causes is added the
fact that during emergent periods the formerly isolated lands were
connected by land bridges, permitting intermigration of the land
floras and faunas, with the introduction of their parasites and
parasitic diseases, we learn that while the climatic environment is of
fundamental importance it is not the only cause for the more rapid
evolution of terrestrial life....
Briefly, then, we may conclude that the markedly varying climates of
the past seem to be due primarily to periodic changes in the
topographic form of the earth’s surface, plus variations in the amount
of heat stored by the oceans. The causation for the warmer
interglacial climates is the most difficult of all to explain, and it
is here that factors other than those mentioned may enter.
Granting all this, there still seems to lie back of all these theories
a greater question connected with the major changes in
paleometeorology. This is: What is it that forces the earth’s
topography to change with varying intensity at irregularly rhythmic
intervals?... Are we not forced to conclude that the earth’s shape
changes periodically in response to gravitative forces that alter the
body-form?”
_Evolution._
Modern evolution, or the theory of life continuously descending from
life with change, may be said to have had its first marked development
in Comte de Buffon (1707–1788), a man of wealth and station, yet an
industrious compiler, a brilliant writer, and a popularizer of science.
He was not, however, a true scientific investigator, and his monument to
fame is his Histoire Naturelle, in forty-four volumes, 1749–1804. A. S.
Packard in his book on Lamarck, his Life and Work, 1901, concludes in
regard to Buffon as follows:
“The impression left on the mind, after reading Buffon, is that even
if he threw out these suggestions and then retracted them, from fear
of annoyance or even persecution from the bigots of his time, he did
not himself always take them seriously, but rather jotted them down as
passing thoughts.... They appeared thirty-four years before Lamarck’s
theory, and though not epoch-making, they are such as will render the
name of Buffon memorable for all time.”
Chevalier de Lamarck (1744–1829) may justly be regarded as the founder
of the doctrine of modern evolution. Previous to 1794 he was a believer
in the fixity of species, but by 1800 he stood definitely in favor of
evolution. Locy in his Biology and its Makers, 1908, states his theories
in the following simplified form:
“Variations of organs, according to Lamarck, arise in animals mainly
through use and disuse, and new organs have their origin in a
physiological need. A new need felt by the animal [due to new
conditions in its life, or the environment] expresses itself on the
organism, stimulating growth and adaptations in a particular
direction.”
To Lamarck, “inheritance was a simple, direct transmission of those
superficial changes that arise in organs within the lifetime of an
individual owing to use and disuse.” This part of his theory has come to
be known as “the inheritance of acquired characters.”
Georges Cuvier (1769–1832), a peer of France, was a decided believer in
the fixity of species and in their creation through divine acts. In 1796
he began to see that among the fossils so plentiful about Paris many
were of extinct forms, and later on that there was a succession of
wholly extinct faunas. This at first puzzling phenomenon he finally came
to explain by assuming that the earth had gone through a series of
catastrophes, of which the Deluge was the most recent but possibly not
the last. With each catastrophe all life was blotted out, and a new
though improved set of organisms was created by divine acts. The
Cuvierian theory of catastrophism was widely accepted during the first
half of the nineteenth century, and in America Louis Agassiz was long
its greatest exponent. It was this theory and the dominance of the
brilliant Cuvier, not only in science but socially as well, that blotted
out the far more correct views of the more philosophical Lamarck, who
held that life throughout the ages had been continuous and that through
individual effort and the inheritance of acquired characters had evolved
the wonderful diversity of the present living world.
In 1830 there was a public debate at Paris between Cuvier and Geoffroy
Saint-Hilaire, the one holding to the views of the fixity of species and
creation, the other that life is continuous and evolves into better
adapted forms. Cuvier, a gifted speaker and the greatest debater zoology
ever had, with an extraordinary memory that never failed him, defeated
Saint-Hilaire in each day’s debate, although the latter was in the
right.
A book that did a great deal to prepare the English-speaking people for
the coming of evolution was “Vestiges of Creation,” published in 1844 by
an unknown author. In Darwin’s opinion, “the work, from its powerful and
brilliant style ... has done excellent service ... in thus preparing the
ground for the reception of analogous views.” This book was recommended
to the readers of the Journal (=48=, 395, 1845) with the editorial
remark that “we cannot subscribe to all of the author’s views.”
We can probably best illustrate the opinions of Americans on the
question of evolution just before the appearance of Darwin’s great work
by directing attention to James D. Dana’s Thoughts on Species (=24=,
305, 1857). After reading this article and others of a similar nature by
Agassiz, one comes to the opinion that unconsciously both men are
proving evolution, but consciously they are firm creationists. It is
astonishing that with their extended and minute knowledge of living
organisms and their philosophic type of mind neither could see the true
significance of the imperceptible transitions between some species,
which if they do not actually pass into, at least shade towards, one
another.
Dana speaks of “the endless diversities in individuals” that compose a
species, and then states that a living species, like an inorganic one,
“is based on a specific amount or condition of concentered force defined
in the act or law of creation.” Species, he says, are permanent, and
hybrids “cannot seriously trifle with the true units of nature, and at
the best, can only make temporary variations.” “We have therefore reason
to believe from man’s fertile intermixture, that he is one in species:
and that all organic species are divine appointments which cannot be
obliterated, unless by annihilating the individuals representing the
species.”
Through the activities of the French the world was prepared for the
reception of evolution, and now it was already in the minds of many
advanced thinkers. In 1860 Asa Gray sent to the editor of the Journal
(=29=, 1) an article by the English botanist, Joseph D. Hooker, entitled
“On the Origination and Distribution of Species,” with these significant
remarks:
“The essay cannot fail to attract the immediate and profound attention
of scientific men.... It has for some time been manifest that a
re-statement of the Lamarckian hypothesis is at hand. We have this, in
an improved and truly scientific form, in the theories which, recently
propounded by Mr. Darwin, followed by Mr. Wallace, are here so ably
and altogether independently maintained. When these views are fully
laid before them, the naturalists of this country will be able to take
part in the interesting discussion which they will not fail to call
forth.”
Hooker took up a study of the flora of Tasmania, of which the above
cited article is but a chapter, with a view to trying out Darwin’s
theory, and he now accepts it. He says, “Species are derivative and
mutable.” “The limits of the majority of species are so undefinable that
few naturalists are agreed upon them.”
Asa Gray had received from Darwin an advance copy of the book that was
to revolutionize the thought of the world, and at once wrote for the
Journal a Review of Darwin’s Theory on the Origin of Species by means of
Natural Selection (=29=, 153, 1860). This is a splendid, critical but
just, scientific review of Darwin’s epoch-making book. Evidently views
similar to those, of the English scientist had long been in the mind of
Gray, for he easily and quickly mastered the work. He is easy on Dana’s
Thoughts on Species, which were idealistic and not in harmony with the
naturalistic views of Darwin. On the other hand, he contrasts Darwin’s
views at length with those of the creationists as exemplified by Louis
Agassiz, and says “The widest divergence appears.”
Gray says in part:
“The gist of Mr. Darwin’s work is to show that such varieties are
gradually diverged into species and genera through natural selection;
that natural selection is the inevitable result of the struggle for
existence which all living things are engaged in; and that this
struggle is an unavoidable consequence of several natural causes, but
mainly of the high rate at which all organic beings tend to increase.
Darwin is confident that intermediate forms must have existed; that in
the olden times when the genera, the families and the orders diverged
from their parent stocks, gradations existed as fine as those which
now connect closely related species with varieties. But they have
passed and left no sign. The geological record, even if all displayed
to view, is a book from which not only many pages, but even whole
alternate chapters have been lost out, or rather which were never
printed from the autographs of nature. The record was actually made in
fossil lithography only at certain times and under certain conditions
(i.e., at periods of slow subsidence and places of abundant sediment);
and of these records all but the last volume is out of print; and of
its pages only local glimpses have been obtained. Geologists, except
Lyell, will object to this,—some of them moderately, others with
vehemence. Mr. Darwin himself admits, with a candor rarely displayed
on such occasions, that he should have expected more geological
evidence of transition than he finds, and that all the most eminent
paleontologists maintain the immutability of species.
The general fact, however, that the fossil fauna of each period as a
whole is nearly intermediate in character between the preceding and
the succeeding faunas, is much relied on. We are brought one step
nearer to the desired inference by the similar ‘fact,’ insisted on by
all paleontologists, that fossils from two consecutive formations are
far more closely related to each other, than are the fossils of two
remote formations.
It is well said that all organic beings have been formed on two great
laws; Unity of type, and Adaptation to the conditions of existence....
Mr. Darwin harmonizes and explains them naturally. Adaptation to the
conditions of existence is the result of Natural Selection; Unity of
type, of unity of descent.”
Gray’s article was soon followed by another one from Agassiz on
Individuality and Specific Differences among Acalephs, but the running
title is “Prof. Agassiz on the Origin of Species” (=30=, 142, 1860).
Agassiz stoutly maintains his well known views, and concludes as
follows:
“Were the transmutation theory true, the geological record should
exhibit an uninterrupted succession of types blending gradually into
one another. The fact is that throughout all geological times each
period is characterized by definite specific types, belonging to
definite genera, and these to definite families, referable to definite
orders, constituting definite classes and definite branches, built
upon definite plans. Until the facts of Nature are shown to have been
mistaken by those who have collected them, and that they have a
different meaning from that now generally assigned to them, I shall
therefore consider the transmutation theory as a scientific mistake,
untrue in its facts, unscientific in its method, and mischievous in
its tendency.”
Dana, in reviewing Huxley’s well known book, Man’s Place in Nature
(=35=, 451, 1863), holds that man is apart from brute nature because man
exhibits “extreme cephalization” in that he has arms that no longer are
used in locomotion but go rather with the head, and because he has a far
higher mentality and speech. As for the Darwinian theory, the evidence,
he says, “comes from lower departments of life, and is acknowledged by
its advocates to be exceedingly scanty and imperfect.”
The growth of evolution is set forth in the Journal in Asa Gray’s
article on Charles Darwin (=24=, 453, 1882), which speaks of the latter
as “the most celebrated man of science of the nineteenth century,” and,
in addition, as “one of the most kindly and charming, unaffected,
simple-hearted, and lovable of men.” In regard to the rise of evolution
in America, more can be had from Dana’s paper on Asa Gray (=35=, 181,
1888). Here we read, as a sequel to his Thoughts on Species, that the
“paper may be taken, perhaps, as a culmination of the past, just as the
new future was to make its appearance.” Finally, in this connection
there should be mentioned O. C. Marsh’s paper on Thomas Henry Huxley
(=50=, 177, 1895), wherein is recorded the latter’s share in the
upbuilding of the evolutionary theory.
We have seen that originally Dana was a creationist, but in the course
of his long and fruitful life he gradually became an evolutionist, and
rather a Neo-Lamarckian than a Darwinian. This change may be traced in
the various editions of his Manual of Geology, and in the last edition
of 1895 he says his “speculative conclusions” of 1852 in regard to the
origin of species are not in “accord with the author’s present
judgment.” “The evidence in favor of evolution by variation is now
regarded as essentially complete.” On the other hand, while man is
“unquestionably” closely related in structure to the man-apes, yet he is
not linked to them but stands apart, through “the intervention of a
Power above Nature.... Believing that Nature exists through the will and
ever-acting power of the Divine Being, and ... that the whole Universe
is not merely dependent on, but actually is, the Will of one Supreme
Intelligence, Nature, with Man as its culminant species, is no longer a
mystery.”
In America most of the paleontologists are Neo-Lamarckian, a school that
was developed independently by E. D. Cope (1840–1897) through the
vertebrate evidence, and by Alpheus Hyatt (1838–1902) mainly on the
evidence of the ammonites. They hold that variations and acquired
characters arise through the effects of the environment, the mechanics
of the organism resulting from the use and disuse of organs, etc. One of
the leading exponents of this school is A. S. Packard, whose book on
Lamarck, His Life and Work, 1901, fully explains the doctrines of the
Neo-Lamarckians.
_The Growth of Invertebrate Paleontology._
How and by whom paleontology has been developed has been fully stated in
the Journal in a very clear manner by Professor Marsh in his memorable
presidential address of 1879, History and Methods of Palæontological
Discovery (=18=, 323, 1879), and by Karl von Zittel in his most
interesting book, History of Geology and Palæontology, 1901. In this
discussion we shall largely follow Marsh.
The science of paleontology has passed through four periods, the first
of them the long _Mystic period_ extending up to the beginning of the
seventeenth century, when the idea that fossils were once living things
was only rarely perceived. The second period was the _Diluvial period_
of the eighteenth century, when nearly everyone regarded the fossils as
remains of the Noachian deluge. With the beginnings of the nineteenth
century there arose in western Europe the knowledge that fossils are the
“medals of creation” and that they have a chronogenetic significance;
also that life had been periodically destroyed through world-wide
convulsions in nature. From about 1800 to 1860 was the time of the
creationists and catastrophists, which may be known as the _Catastrophic
period_. The fourth period began in 1860 with Darwin’s Origin of
Species. Since that time the theory of evolution has pervaded all work
in paleontology, and accordingly this time may be known as the
_Evolutionary period_.
_Mystic Period._—The Mystic period in paleontology begins with the
Greeks, five centuries before the present era, and continues down to the
beginning of the seventeenth century of our time. Some correctly saw
that the fossils were once living marine animals, and that the sea had
been where they now occur. Others interpreted fossil mammal bones as
those of human giants, the Titans, but the Aristotelian view that they
were of spontaneous generation through the hidden forces of the earth
dominated all thought for about twenty centuries.
In the sixteenth century canals were being dug in Northern Italy, and
the many fossils so revealed led to a fierce discussion as to their
actual nature. Leonardo da Vinci (1452–1519) opposed the commonly
accepted view of their spontaneous generation and said that they were
the remains of once living animals and that the sea had been where they
occur. “You tell me,” he said, “that Nature and the influence of the
stars have formed these shells in the mountains; then show me a place in
the mountains where the stars at the present day make shelly forms of
different ages, and of different species in the same place.” However,
nothing came of his teachings and those of his countryman Fracastorio
(1483–1553), who further ridiculed the idea that they were the remains
of the deluge. The first mineralogist, Agricola, described them as
minerals—fossilia—and said that they arose in the ground from fatty
matter set in fermentation by heat. Others said that they were freaks of
nature. Martin Lister (1638–1711) figured fossils side by side with
living shells to show that they were extinct forms of life. In the
seventeenth century, and especially in Italy and Germany, many books
were published on fossils, some with illustrations so accurate that the
species can be recognized to-day. Finally, toward the close of this
century the influence of Aristotle and the scholastic tendency to
disputation came more or less to an end. Fossils were already to many
naturalists once living plants and animals. Marsh states: “The many
collections of fossils that had been brought together, and the
illustrated works that had been published about them, were a foundation
for greater progress, and, with the eighteenth century, the second
period in the history of paleontology began.”
_Diluvial Period._—During the eighteenth century many more books on
fossils were published in western Europe, and now the prevalent
explanation was that they were the remains of the Noachian deluge. For
nearly a century theologians and laymen alike took this view, and some
of the books have become famous on this account, but the diluvial views
sensibly declined with the close of the eighteenth century.
The true nature of fossils had now been clearly determined. They were
the remains of plants and animals, deposited long before the deluge,
part in fresh water and part in the sea. “Some indicated a mild climate,
and some the tropics. That any of these were extinct species, was as yet
only suspected.” Yet before the close of the century there were men in
England and France who pointed out that different formations had
different fossils and that some of them were extinct. These views then
led to many fantastic theories as to how the earth was formed—dreams,
most of them have been called. Marsh says:
“The dominant idea of the first sixteen centuries of the present era
was, that the universe was made for Man. This was the great obstacle
to the correct determination of the position of the earth in the
universe, and, later, of the age of the earth.... In a superstitious
age, when every natural event is referred to a supernatural cause,
science cannot live.... Scarcely less fatal to the growth of science
is the age of Authority, as the past proves too well. With freedom of
thought, came definite knowledge, and certain progress;—but two
thousand years was long to wait.”
One of the most significant publications of this period was Linnæus’s
Systema Naturæ, which appeared in 1735. In this work was introduced
binomial nomenclature, or the system of giving each plant and animal
species a generic and specific name, as _Felis leo_ for the lion. The
system was, however, not established until the tenth edition of the work
in 1758, which became the starting point of zoological nomenclature.
Since then there has been added another canon, the law of priority,
which holds that the first name applied to a given form shall stand
against all later names given to the same organism.
_Catastrophic Period._—With the beginning of the nineteenth century
there started a new era in paleontology, and this was the time when the
foundations of the science were laid. The period continued for six
decades, or until the time of the Origin of Species. Marsh says that now
“method replaced disorder, and systematic study superseded casual
observation.” Fossils were accurately determined, comparisons were made
with living forms, and the species named according to the binomial
system. However, every species, recent and extinct, was regarded as a
separate creation, and because of the usually sharp separation of the
superposed fossil faunas and floras, these were held to have been
destroyed through a series of periodic catastrophes of which the
Noachian deluge was the last.
Lamarck between 1802 and 1806 described the Tertiary shells of the Paris
basin. Comparing them with the living forms, he saw that most of the
fossils were of extinct species, and in this way he came to be the
founder of modern invertebrate paleontology. He also maintained after
1801 that life has been continuous since its origin and that nature has
been uniform in the course of its development. Marsh adds:
“His researches on the invertebrate fossils of the Paris Basin,
although less striking, were not less important than those of Cuvier
on the vertebrates; while the conclusions he derived from them form
the basis of modern biology.”
“Lamarck was the prophetic genius, half a century in advance of his
time.”
Cuvier established comparative anatomy and vertebrate paleontology, and
was one of the first to point out that fossil animals are nearly all
extinct forms. He came to the latter conclusion in 1796 through a study
of fossil elephants found in Europe. “Cuvier enriched the animal kingdom
by the introduction of fossil forms among the living, bringing all
together into one comprehensive system.” This opened to him entirely new
views respecting the theory of the earth, and he devoted more than
twenty-five years to developing the theories of special creation and
catastrophism, described in his Discourse on the Revolutions of the
Surface of the Globe. “With all his knowledge of the earth, he could not
free himself from tradition, and believed in the universality and power
of the Mosaic deluge. Again, he refused to admit the evidence brought
forward by his distinguished colleagues against the permanence of
species, and used all his great influence to crush out the doctrine of
evolution, then first proposed” (Marsh).
In England it was William Smith (1769–1839) who independently discovered
the chronogenetic significance of fossils, and in their stratigraphic
superposition indicated the way for the study of historical geology. He
first published on this matter in 1799, but his completed statements
came in works entitled “Strata identified by Organized Fossils,”
1816–1820, and “Stratigraphical System of Organized Fossils,” 1817.
Invertebrate paleontology in America during the Catastrophic period had
its beginning in Lesueur, who in 1818 described the Ordovician gastropod
_Maclurites magna_. All of the paleontologists of this time were
satisfied to describe species and genera and to ascertain in a broad way
the stratigraphic significance of the fossil faunas and floras. James
Hall in 1854 (=17=, 312) knew of 1588 species, described and
undescribed, in the New York system, while in England Morris listed in
that year 8300 Paleozoic forms. In 1856 Dana recites the known fossil
species as follows (=22=, 333): The whole number of known American
species of animals of the Permian to Recent is about 2000; while in
Britain and Europe, there were over 20,000 species. In the Permian we
have none, while Europe has over 200 species. In the Triassic we have
none, Europe 1000 species; Jurassic 60, Europe over 4000; Cretaceous 350
to 400, Europe about 6000; Tertiary hardly 1500, Europe about 8000.
Since that time nearly all of the larger American Paleozoic faunas have
been developed, but there are thousands of species yet to be described.
Who the more prominent American paleontologists of this period were has
been told in the section on the development of the geological column.
The grander paleontologic results of the Catastrophic period have been
so well stated by Marsh that it is worth our while to repeat them here:
“It had now been proved beyond question that portions at least of the
earth’s surface had been covered many times by the sea, with
alternations of fresh water and of land; that the strata thus
deposited were formed in succession, the lowest of the series being
the oldest; that a distinct succession of animals and plants had
inhabited the earth during the different geological periods; and that
the order of succession found in one part of the earth was essentially
the same in all. More than 30,000 new species of extinct animals and
plants had now been described. It had been found, too, that from the
oldest formations to the most recent, there had been an advance in the
grade of life, both animal and vegetable, the oldest forms being among
the simplest, and the higher forms successively making their
appearance.
It had now become clearly evident, moreover, that the fossils from the
older formations were all extinct species, and that only in the most
recent deposits were there remains of forms still living.... Another
important conclusion reached, mainly through the labors of Lyell, was,
that the earth had not been subjected in the past to sudden and
violent revolutions; but the great changes wrought had been gradual,
differing in no essential respect from those still in progress.
Strangely enough, the corollary to this proposition, that life, too,
had been continuous on the earth, formed at that date no part of the
common stock of knowledge. In the physical world, the great law of
‘correlation of forces’ had been announced, and widely accepted; but
in the organic world, the dogma of the miraculous creation of each
separate species still held sway.”
_Evolutionary Period._—This period begins with 1860 and the publication
of Darwin’s Origin of Species (late in 1859). It is the period of modern
paleontology, and is dominated by the belief that universal laws pervade
not only inorganic matter, but all life as well. Louis Agassiz had been
in America fourteen years when Darwin’s book appeared, and his wonderful
influence in bringing the zoology of our country to a high stand and the
further influence he exerted through his students was bound to react
beneficially on invertebrate paleontology. Shortly after the beginning
of this period, or in 1867, Alpheus Hyatt, one of Agassiz’s students,
began to apply the study of embryology to fossil cephalopods, showing
clearly that these shells retain a great deal of their growth stages or
ontogeny. This method of study was then followed by R. T. Jackson, C. E.
Beecher, and J. P. Smith, and has been productive of natural
classifications of the Cephalopoda, Brachiopoda, Trilobita, and
Echinoidea.
The dominant invertebrate paleontologist of this period was of course
James Hall, who described about 5000 species of American Paleozoic
fossils. He also built up the New York State Museum, while around his
private collections of fossils have been developed the American Museum
of Natural History in New York City and the Walker Museum at the
University of Chicago. In his most important laboratory of paleontology
at Albany, there have been trained either wholly or in part the
following paleontologists: F. B. Meek, C. A. White, R. P. Whitfield, C.
D. Walcott, C. E. Beecher, John M. Clarke, and Charles Schuchert.
In Canada, through the work of the Geological Survey of the Dominion,
came the paleontologists Elkanah Billings and, later on, J. F.
Whiteaves. The “father of Canadian paleontology,” Sir William Dawson,
who developed independently, was active in all branches of the science
and did much to unravel the geology of eastern Canada. No organism has
been more discussed and more often rejected and accepted as a fossil
than his “dawn animal of Canada,” _Eozoon canadense_, first described in
1865. His son, George M. Dawson, was one of the directors of the
Geological Survey of Canada. Finally the extensive paleontology of the
Cambrian of Canada was worked out by another self-made paleontologist,
G. F. Matthew.
_Paleobotany._—American paleobotany was developed during this, the
fourth period, through the state and national surveys, first in Leo
Lesquereux, a Swiss student induced by Agassiz to come to America, and
in J. S. Newberry. The second generation of paleobotanists is
represented by Lester F. Ward and W. N. Fontaine, and the third
generation, the present workers, includes F. H. Knowlton, David White,
Arthur Hollick, and E. W. Berry. A new line of paleobotanical work, the
histology of woody but pseudomorphous remains, has been developed by G.
R. Wieland.
The grander results of the study of paleontology during the evolutionary
period may be summed up with the conclusions of Marsh:
“One of the main characteristics of this epoch is the belief that all
life, living and extinct, has been evolved from simple forms. Another
prominent feature is the accepted fact of the great antiquity of the
human race. These are quite sufficient to distinguish this period
sharply from those that preceded it.”
Charles Darwin’s work at once aroused attention, and brought about in
scientific thought a revolution which “has influenced paleontology as
extensively as any other department of science.... In the [previous
period] species were represented independently by parallel lines; in
the present period, they are indicated by dependent, branching lines.
The former was the analytic, the latter is the synthetic period.”
_Synthetic Period._—What is to be the next trend in paleontology?
Clearly it is to be the Synthetic period, one that Marsh in 1879
indicated in these words: “But if we are permitted to continue in
imagination the rapidly converging lines of research pursued to-day,
they seem to meet at the point where organic and inorganic nature become
one. That this point will yet be reached, I cannot doubt.”
This Synthetic period, foreshadowed also in Herbert Spencer’s Synthetic
Philosophy, has not yet arrived, but before long another great leader
will appear. We have the prophecy of his coming in such books as The
Fitness of the Environment, by Lawrence J. Henderson, 1913; The Origin
and Nature of Life, by Benjamin Moore, 1913; The Organism as a Whole, by
Jacques Loeb, 1916; and The Origin and Evolution of Life, by Henry F.
Osborn, 1917.
In all nature, inorganic and organic, there is continuity and
consistency, beauty and design. We are beginning to see that there are
eternal laws, ever interacting and resulting in progressive and
regressive evolutions. The realization of these scientific revelations
kindles in us a desire for more knowledge, and the grandest revelations
are yet before us in the synthesis of the sciences.
_Notes._
Footnote 3:
For more detail in regard to these tillites and the older ones see
Climates of Geologic Time, by Charles Schuchert, being Chapter XXI in
Huntington’s Climatic Factor as Illustrated in Arid America,
Publication No. 192 of the Carnegie Institution of Washington, 1914.
Also Arthur P. Coleman’s presidential address before the Geological
Society of America in 1915, Dry Land in Geology, published in the
Society’s Bulletin, 27, 175, 1916.
III
A CENTURY OF GEOLOGY.—STEPS OF PROGRESS IN THE INTERPRETATION OF LAND
FORMS