_Introduction._
The American Journal of Science, “one of the greatest influences in
American geology,” founded in 1818, has published a little more than
92,000 pages of scientific matter. Of geology, including mineralogy,
there appear to be upward of 20,000 pages. What a vast treasure house of
geologic knowledge is stored in these 194 volumes, and how well the
editors have lived up to their proposed “plan of work” as stated in the
opening volume, where Silliman says: “It is designed as a deposit for
original American communications” in “the physical sciences ... and
especially our mineralogy and geology” (=1=, v, 1818)! Not only is it
the oldest continuously published scientific journal of this country,
but it has proved itself to be “perhaps the most important geological
periodical in America” (Merrill). It is impossible to adequately present
in this memorial volume of the Journal the contents of the articles on
the geological sciences.
Editor Silliman was not only the founder of the Journal, but the
generating center for the making of geologists and promoting geology
during the rise of this science in America. For nearly three decades,
the workers came to him for counsel and help, and he had a kind paternal
word for them all. This influence is also shown in the many letters
which were addressed to him, and which he published in the Journal. A
similar influence, paternal care, and constructive criticism were
continued by James D. Dana, and especially in his earlier career as
editor.
Not including mineralogy, there are in the Journal upward of 1500
distinct articles on geology. Of these, over 400 are on vertebrate
paleontology, about 325 on invertebrate paleontology, and 90 on
paleobotany. Of articles bearing on historical geology there are about
160, and on stratigraphic geology more than 360. In addition to all
this, there are more than 2000 pages of geologic matter relating to
books and of letters communicated to the editors Silliman and Dana. We
may summarize with Doctor Merrill’s statement in his well-known
Contributions to the History of American Geology:
“From its earliest inception geological notes and papers occupied a
prominent place in its pages, and a perusal of the numbers from the
date of issue down to the present time will, alone, afford a fair idea
of the gradual progress of American geology.”
Before presenting a synopsis of the more important steps in the progress
of historical geology in America, it will be well to introduce a rapid
survey of the rise of geology in Europe, for, after all, American
geology grew out of that of England, France and Germany. This dependence
was conspicuously true during the first four decades of the previous
century. With the rise of the first New York State Survey (1836–1843)
and that of Pennsylvania (1836–1844, 1858), American geology became more
or less independent of Europe. Finally, this article will conclude with
a survey of the rise of paleometeorology, paleogeography, evolution, and
invertebrate paleontology.
_The Rise of Geology in Europe._
_Mineral Geology._—The geological sciences had their rise in the study
of minerals as carried on by the German chemist and physician George
Bauer (1494–1555), better known as Agricola. Bauer originated the
critical study of minerals, but did not distinguish his “fossilia,” the
remains of organisms, from the inorganic crystal forms. Mineral geology
endured until the close of the eighteenth century.
_Cosmogonists._—Then came the expounders of the earth’s origin, the
cosmogonists of the sixteenth to the end of the eighteenth centuries.
The fashion of this time was to write histories of the earth derived out
of the imagination.
_Earliest Historical Geology._—Even though Giovanni Arduino (1713–1795)
of Padua was not the first to classify the rocks into three series
according to their age, he did this more clearly than any one else
before his time. The rocks about Verona he grouped in 1759 into Primary,
Secondary, Tertiary, and Volcanic. This three-fold classification came
into general use, though modified with time.
Early in the nineteenth century it had become plain that formations of
very varying ages were included in each one of the three series. Through
the study of the fossils and the recognition of the fact that mountain
ranges have been raised at various times, causing younger fossiliferous
strata to take on the characters of the Primary, it was seen that these
terms of Arduino had lost their original significance.
The first one to describe in detail a local stratigraphic sequence was
Johann Gottlob Lehmann (died 1767). In 1756 he published “one of the
classics of geological literature,” distinguishing clearly thirty
successive sedimentary deposits, some of which he said had fossils, but
he did not use them to distinguish the strata.
What Lehmann did for the Permian system, George Christian Füchsel
(1722–1773) did even better for the Triassic of Thuringia, in 1762 and
1773. He pointed out not only the sequence, but also how the gently
inclined strata rest upon the older upturned masses of the mountains;
also that some formations have only marine fossils, while others have
only terrestrial forms and thus indicate the proximity of land. The
deformed strata he thought had fallen into the hollows within the earth,
great caverns that had also consumed much of the oceanic waters and had
in so doing greatly lowered the sea-level. It was Füchsel who first
introduced the theory of universal formations, and who defined the term
formation, using it as we now do, system or period. Even though Lehmann
and Füchsel showed that there was a definite order and process in the
formation of the earth’s crust, their example was barren of followers
until the beginning of the eighteenth century.
_Wernerian Geology or Geognosy._—We come now to the time of Abraham
Gottlob Werner (1749–1817), who from 1775 to 1817 was professor of
mining and mineralogy in the Freiberg Academy of Mines. Geikie, in his
most interesting Founders of Geology, says that Werner “bulks far more
largely in the history of geology than any of those with whom up to the
present we have been concerned—a man who wielded an enormous authority
over the mineralogy and geology of his day.” “Although he did great
service by the precision of his lithological characters and by his
insistence on the doctrine of geological succession, yet as regards
geological theory, whether directly by his own teaching, or indirectly
by the labors of his pupils and followers, much of his influence was
disastrous to the higher interests of geology.”
Werner arranged the crust of the earth into a series of formations, as
had been done previously by Lehmann and Füchsel, and one of his
fundamental postulates was that all rocks were chemically precipitated
in the ocean as “universal formations.” For this reason Werner’s school
were called the Neptunists. Nowhere, however, did he explain how and
where the deep and primitive ocean had disappeared.
According to Werner, the first formed or oldest rocks were the
chemically deposited Primitive strata, including granite and other
igneous and metamorphic rocks. On these followed the Transition rocks,
the earliest sediments of mechanical origin, and above them the Floetz
rocks, a term for the horizontal stratified rocks. These last he said
were partly of chemical but chiefly of mechanical origin. Last of all
came the Alluvial series.
The existence of volcanoes had been pointed out long before Werner’s
time by the Italian school of geologists, but as for “the universality
and potency of what is now termed igneous action,” all was “brushed
aside by the oracle of Freiberg.” Reactions between the interior and
exterior of our earth “were utterly antagonistic to Werner’s conception
of the structure and history of the earth.” To him, volcanoes were
“burning mountains” that arose from the combustion of subterranean beds
of coal, spontaneously ignited.
The breaking down of the Wernerian doctrines began with two of Werner’s
most distinguished pupils, D’Aubuisson de Voisins (1769–1819) and Von
Buch. The former in 1803 had accepted Werner’s aqueous origin of basalt,
but after studying the celebrated and quite recent volcanic area of
Auvergne he recanted in 1804. Here he saw the basaltic rocks lying upon
and cutting through granite, and in places more than 1200 feet thick.
“If these basaltic rocks were lavas,” says Geikie, “they must, according
to the Wernerian doctrine, have resulted from the combustion of beds of
coal. But how could coal be supposed to exist under granite, which was
the first chemical precipitate of a primeval ocean?”
Leopold von Buch (1774–1853), “the most illustrious geologist that
Germany has produced,” after two years spent in Norway was satisfied
“that the rocks in the Christiania district could not be arranged
according to the Wernerian plan, which there completely broke down. Von
Buch found a mass of granite lying among fossiliferous limestones which
were manifestly metamorphosed, and were pierced by veins of granite,
porphyry, and syenite.” Even so, he was not ready to abandon the
teachings of his master. After a study of the mountain systems of
Germany, however, “he declared that the more elevated mountains had
never been covered by the sea, as Werner had taught, but were produced
by successive ruptures and uplifts of the terrestrial crust” (Geikie).
_Rise of Geology and Conformism._—Modern geology has its rise in James
Hutton (1726–1797) of Edinburgh, Scotland. In 1785 and 1795, Hutton
published his Theory of the Earth, with Proofs and Illustrations. His
“immortal theory” is his only work on geology. “Fortunately for Hutton’s
fame and for the onward march of geology, the philosopher numbered among
his friends the illustrious mathematician and natural philosopher, John
Playfair (1748–1819), who had been closely associated with him in his
later years, and was intimately conversant with his geological
opinions.” In 1802, Playfair published his Illustrations of the
Huttonian Theory of the Earth, of which Geikie says, “Of this great
classic it is impossible to speak too highly,” as it is at the basis of
all modern geology.
One of Hutton’s fundamental doctrines is that the earth is internally
hot and that in the past large masses of molten material, the granites,
have been intruded into the crust. It was these igneous views that led
to his followers being called the Plutonists. Another of his great
doctrines was that “the ruins of an earlier world lie beneath the
secondary strata,” and that they are separated by what is now known as
unconformity. He clearly recognized a lost interval in the broken
relation of the structures, and that the ruins, the detrital materials,
of one world after another are superposed in the structure of the earth.
Hutton also held that the deformation of once horizontally deposited
strata was probably brought about at different periods by great
convulsions that shook the very foundations of the earth. After a
convulsion, there was a long time of erosion, represented by the
unconformity. Geikie says, “The whole of the modern doctrine of earth
sculpture is to be found in the Huttonian theory.”
The Lyellian doctrine of metamorphism had its origin in Hutton, for he
showed that invading igneous granite had altered, through its heat and
expanding power, the originally waterlaid sediments, and that the
schists of the Alps had been born of the sea like other stratified
rocks.
Hutton is the father of the Uniformitarian principle, for he “started
with the grand conception that the past history of our globe must be
explained by what can be seen to be happening now, or to have happened
only recently. The dominant idea in his philosophy is that the present
is the key to the past.” This principle has been impressed on all later
geologists by Sir Charles Lyell, and is the chief cornerstone of modern
geology.
The principle of uniformitarianism has underlain geologic interpretation
since the days of Hutton, Playfair, and Lyell. However, it is often
applied too rigidly in interpretations based upon the present
conditions, because in the past there were long times when the
topographic features of the earth were very different from those of
to-day. Throughout the Paleozoic, and, less markedly, the Mesozoic, the
oceans flooded the lands widely (at times over 60 per cent of the total
area), highlands were inconspicuous, sediments far scarcer, and climates
warm and equable throughout the world. Highland conditions, and
especially the broadly emergent continents of the present, were only
periodically present in the Paleozoic and then for comparatively short
intervals between the periods. Therefore rates of denudation, solution,
sedimentation, and evolution have varied greatly throughout the
geological ages. These differences, however, relate to degrees of
operation, and not to kinds of processes; but the differences in degree
of operation react mightily on our views as to the age of the earth.
Geologic time had, for Hutton, no “vestige of a beginning, no prospect
of an end.” In other words, geologic time is infinite. He did not,
however, discover a method by which the chronology of the earth could be
determined.
_First Important Text-books._—In 1822 appeared the ablest text-book so
far published, and the pattern for most of the later ones, Outlines of
the Geology of England and Wales, by W. D. Conybeare (1787–1857) and W.
Phillips (1775–1828). “In this excellent volume all that was then known
regarding the rocks of the country, from the youngest formations down to
the Old Red Sandstone, was summarized in so clear and methodical a
manner as to give a powerful impulse to the cultivation of geology in
England” (Geikie). This book is reviewed at great length by Edward
Hitchcock in the Journal (=7=, 203, 1824).
To indicate how far historical geology had progressed up to 1822 in
England, a digest of the geological column as presented in this
text-book is given in the following table, along with other information.
A text-book writer of yet greater influence was Charles Lyell
(1797–1875), whose Principles of Geology appeared in three volumes
between 1830 and 1833. This and his other books were kept up to date
through many editions, and his Elements of Geology is, as Geikie says,
“the hand book of every English geologist” working with the
fossiliferous formations.
_The Rise of Geology in North America._
_The Generating Centers._—In America, geology had its rise independently
in three places: in the two scientific societies of Boston and
Philadelphia, and dominantly in Benjamin Silliman of Yale College.
Stated in another way, we may say that geology in America had its origin
in the following pioneers and founders: first, in William Maclure at
Philadelphia, and next in Benjamin Silliman at New Haven. Through the
influence of the latter, Amos Eaton, the botanist, became a geologist
and taught geology at Williams College and later at the Rensselaer
School in Troy, New York. Through the same influence Rev. Edward
Hitchcock also became a geologist and taught the subject after 1825 at
Amherst College.
Silliman was the first to take up actively the teaching of mineralogy
and geology based on collections of specimens. He spread the knowledge
in popular lectures throughout the Eastern States, graduated many a
student in the sciences, making of some of them professional teachers
and geologists, provided all with a journal wherein they could publish
their research, organized the first geological society and through his
students the first official geological surveys, and by kind words and
acts stimulated, fostered, and held together American scientific men for
fifty years. Of him it has been truly said that he was “the guardian of
American science from its childhood.”
_The American Academy in Boston._—The second oldest scientific society,
but the first one to publish on geological subjects, was the American
Academy of Arts and Sciences of Boston, instituted and publishing since
1780. Up to the time of the founding of this Journal, there had appeared
in the publications of the American Academy about a dozen papers of a
geologic character, none of which need to be mentioned here excepting
one by S. L. and J. F. Dana, entitled “Outlines of the Mineralogy and
Geology of Boston,” published in 1818. This is an early and important
step in the elucidation of one of the most intricate geologic areas, and
is further noteworthy for its geologic map, the third one to appear, the
older ones being by Maclure and Hitchcock (Merrill).