up what they caught. But I saw the coyote the next day, and he looked
so very empty that I think that the red fox must have taken all the
rabbit meat for himself. Most likely he left his cousin just the ears
for his part, with a rabbit's foot to carry in his pocket for good
luck.
GLACIAL GEOLOGY IN AMERICA.
BY PROF. DANIEL S. MARTIN.
Under this title the vice-president of Section E (Geology) of the
American Association--Prof. Herman L. Fairchild, of the University of
Rochester, New York--gave an admirable _résumé_ of the whole history,
progress, and scope of the study of ice phenomena in North America, as
the opening address before the section at the recent Boston meeting.
Apart from the interest of the subject in itself considered, this
address was a model of what such addresses should be. While strictly
scientific, without the least attempt at rhetorical effect, it was at
the same time so clear, so well arranged and so simple in language,
that any intelligent auditor could enjoy it and grasp it, and carry
away a distinct impression of the gradual development and present
status of this great department of geological study. Professor
Fairchild's choice of his subject was happy also in its fitness to the
occasion, as covering almost exactly the half century of the life of
the association, though going back indeed a few years further, into
the period of the earlier society which developed into the association
in 1848.
The great body of phenomena comprised under the term "drift," and the
smoothed and scratched surfaces of rock, etc., had been by no means
unnoticed by the early students of American geology, but they were
attributed to violent and widespread water action, and were spoken of
in general as "diluvial" formations. When the agency of ice began to
be recognized, it was regarded as that of floating and stranding
bergs; and this view for a long time contended with the theory of
glacial action, even when the latter had been adopted and advocated by
eminent students of the subject.
The first allusion to drifting ice as the agent of transportation of
bowlders, etc., appears to have been made as early as 1825, by one
Peter Dobson, of Connecticut, in a letter to Prof. Benjamin Silliman,
of Yale College. Sir Roderick Murchison, who became the great champion
of this view, credits Mr. Dobson's letter with giving him the first
suggestion of it. Twelve years later, in 1837, T. A. Conrad made the
earliest reference to land ice as the cause of our drift phenomena; he
does this in very striking words when read in the light of the studies
and determinations of later years, although of course imperfectly and
vaguely.
Meanwhile, however, Agassiz and others had been working among the
glaciers of the Alps, and their views as to a great period of former
extension, in Europe and the British Isles, were finding some
acceptance abroad. In this country, Prof. Edward Hitchcock, in his
address as retiring president of the Association of American
Geologists, in 1841, gave a broad and careful review of the drift
phenomena in eastern North America, and referred to the work of
Agassiz, Buckland, and Lyell with great interest, as having given him
"a new geological sense" in observing these phenomena, and said, with
prophetic foresight, "Henceforth, glacial action must form an
important chapter in geology."
But the time was not ripe for the understanding and acceptance of the
glacial theory as a later generation has come to know it. The studies
of Agassiz and his _confrères_ had been among glaciers upon mountain
slopes, and hence, while many of the drift phenomena were strikingly
accounted for, others were not and could not be. So it came to pass
that, while Professor Hitchcock and others in this country were
strongly impressed, they were not satisfied, and held for years an
uncertain position. The glacial indications conformed in some aspects
to the theory, but not in others; the striæ and groovings, instead of
following valleys, all had a general trend to the southward, and the
bowlders were carried across great depressions and deposited upon
heights. How could these conditions be due to glaciers? Could ice flow
uphill, or move long distances over level areas? These and other
phenomena, such as the peculiar distribution of drift material, in
"drumlin" ridges and the like, had no explanation. Hence,
notwithstanding President Hitchcock's utterances above quoted, and his
similar Postscript on the subject of drift and moraines, appended in
the same year to his volume on the Geology of Massachusetts, we find
him in 1843, when again addressing the Association of Geologists,
adopting a modified tone, dwelling upon these points of difficulty,
and seeking a compromise view, which he called "glacio-aqueous." The
great influence also of Murchison and Lyell had been thrown into the
scale in favor of the iceberg theory, and this fact doubtless had much
to do with the slow development of true conceptions. Lyell visited
America in 1842, and was present at the American Geologists' meeting,
advocating the floating-ice doctrine, to which most of our observers
already leaned; and so the views of Agassiz and the glacial school had
to wait for a decade before they found general acceptance or even
audience.
This, we may note in passing, is but one marked instance out of many
in the history of science, wherein the personal influence of eminent
leaders has obstructed and retarded the advance of true knowledge. The
whole recognition of the Cambrian system, as pre-Silurian and
distinct, was suppressed and prevented for many years by Murchison's
intense opposition to the views of Sedgwick. Similar facts might be
cited in this country, did we care to mention names. Science can not
claim, as is sometimes asserted, that it possesses or imparts any
entire exemption from the influence of authority, and bestows complete
independence from the tendency to "swear to the words of a master."
Of the New York geologists, Vanuxem alone, in his Geology of the Third
District, 1842, inclined to the glacial theory; the others--Emmons,
Mather, and Hall--advocated floating ice, the latter urging as a chief
objection the absence of any great northern highlands from which
glaciers could extend southward. Prof. Henry D. Rogers advocated De la
Beche's view, of great catastrophic waves or _débacles_ of water and
ice, produced by sudden uplifts of the floor of a circumpolar ocean,
and sweeping southward with tremendous power over the middle
latitudes. These views were presented by him in 1844, at the
Washington meeting of the geologists, and are to us a most curious
illustration of the old "cataclysmic" phase of geological conceptions.
Two years later Agassiz came to America, and at once set about
studying the ice evidences here, first in the White Mountains and then
around the Great Lakes. At the first meeting of the American
Association, in 1848, he presented his views as to the identity of our
phenomena with those studied by himself, Desor, and Guyot abroad. His
views were not very warmly received, however, and he did not attempt
their public presentation again for some years, turning his attention
more to the field of zoölogy. In 1850, in a work on Lake Superior, he
refers somewhat sharply to the prejudice that seemed to prevail in
relation to this subject.
From this time, however, the aqueous theories began to be less
strongly presented; and a new generation of geologists was coming on,
largely under the training of Guyot and Agassiz, and more open to
their observed results. C. B. Adams, in 1850, presented a view nearly
akin to that adopted by Dana a few years later, of an elevation of the
high northern latitudes, resulting in a southward-moving glacial
sheet, and a subsequent depression connected with its retreat, to
account for the stratified deposits. Professor Dana accepted this
doctrine in his presidential address before the association in 1855,
adding the "Terrace period" of partial re-elevation. From this time he
became the leader of the American glacialists, and his great Manual,
issued in 1862, carried these views into all the colleges of the
country.
In 1857 Prof. Edward Hitchcock published an important treatise on
Surface Geology, particularly of the Connecticut Valley, in the
Smithsonian Contributions to Knowledge. In this paper he noted the
distinction, so important and now so familiar, between local striæ and
those with the general southward course of the "drift." Two years
later his son, Prof. C. H. Hitchcock, extended this distinction
widely over New England. In 1863 the report of progress of the
Geological Survey of Canada gave an extended review of the surface
geology, by Prof. Robert Bell, in which he fully adopted the glacial
theory. Meantime, also, Professor Ramsay, in England, had abandoned
the iceberg doctrine for that of glaciers.
In 1866 and 1867 important papers appeared by Charles Whittlesey, and
one by Edward Hungerford; this last, read before the association,
adopted the general views of Agassiz, with some important limitations
now generally received. In the same year the revised edition of Dana's
Manual gave yet fuller statement and wider diffusion to the generally
accepted views as held to-day.
Professor Fairchild sums up this historical sketch as comprising four
periods--viz., prior to 1841, undisputed reign of diluvial hypotheses;
1841 to 1848, suggestion and discussion of glacial hypotheses; 1849 to
1866, gradual acceptance of the latter view; from 1867 onward,
development of glacial geology.
From this point, the address was occupied with consideration of the
various aspects of the subject as studied and wrought out during the
past twenty years by numerous observers. These are grouped under four
main heads, each with various subdivisions--viz., (1) the ice sheet,
as to its area, its thickness, its centers of dispersion, its
migration of centers, etc.; (2) the ice period, as to its cause, its
divisions, its duration, its distance in time; (3) the interpretation
of special phenomena, such as moraines, drumlins, eskers, "kettles,"
and the like, valley drift, terraces, loess, etc.; and (4) existing
glaciers, as discovered on our high mountains of the far West, and as
studied in closer relation to the ancient phenomena in the great ice
cap of Greenland and the immense glacier development in Alaska.
It is impossible to go into a detailed review of the numerous points
of interest covered in this discussion. Suffice it to say that one who
heard or who reads it finds an admirably clear and condensed account
of all the problems and phenomena that have been and that are now
encountered in the study of glacial geology on this continent, and of
their gradual interpretation and solution by the combined labors of
many students. The progress of knowledge over this wide field,
advancing step by step, amid conflicting views and perplexing
conditions, is beautifully shown, and leaves a very striking
impression on the mind, of the difficulties and the successes of
scientific research. Nor is Professor Fairchild disposed to claim too
much or assert too strongly. He recognizes that, with all that has
been met and mastered, there are still questions unsolved, and laurels
to be won by others.
Among the facts brought out, a few may be briefly alluded to. The
early abandonment of Agassiz's original view of a vast extension of
the polar snow caps, and the recognition of separate centers of
continental glaciation, now distinctly determined as three in
number--a western, a central, and an eastern--the former being the
earliest, and the others following in succession; the recognition by
the Western geologists of the twofold character of the Glacial epoch,
as also determined in western Europe, but less markedly traceable in
our Eastern States, though now generally admitted; in close relation
to this the determination of the line of the great terminal moraine,
traced by successive observers from the Atlantic seaboard to
Minnesota, and the subsequent recognition of an older, eroded, and
fragmentary morainal "fringe," marking the line of the earlier ice
sheet, somewhat beyond the later. With regard to the actual distance
of the last glacial retreat, as expressed in years, Professor
Fairchild is both cautious and frank. He notes the general consensus
of recent observers toward a much shorter period than was formerly
supposed--from five to ten or perhaps fifteen thousand years. At the
same time, there are many elements of uncertainty involved, and the
problem is by no means settled. The Niagara gorge, so long looked upon
as a possible chronometer, grows more complicated as it is further
studied; the rate of erosion has evidently varied much with the volume
of water carried by the river; and this, in turn, has varied with the
changes of level, and consequently of drainage routes, in the basin of
the Great Lakes. There have been times when only the Erie waters
flowed through the Niagara outlet, the upper lake drainage passing
eastward independently, until a gradual northern rise of the land,
which is proved to be still going on, turned the entire drainage into
the present St. Clair route from Lake Huron into Lake Erie, and so
through Niagara.
This point leads us to digress for a moment from the address under
consideration to allude to a very interesting department of study that
is now growing into prominence--to wit, the restoration of pre-glacial
geography and hydrography, and the genesis of our existing river and
lake systems throughout the northern part of the country. The
discussions and results in regard to Niagara and the Great Lakes are
somewhat familiar, but the work on the rivers and smaller lakes is not
so widely known. Professor Fairchild himself has done much in relation
to the "central lakes" of New York State; and one very interesting
paper of this kind on The Development of the Ohio River was read
before the section by Prof. William G. Light, of Granville, Ohio,
besides many papers by others on similar topics.
The work done within a few years upon the glaciers of Arctic America
has proved peculiarly fruitful in results. Here, again, the whole
subject is reviewed historically, and the name and work of each
observer are impartially noted. Much of the difficulty encountered by
the glacial theory arose, as we have seen, from the fact that only
mountain glaciers had been studied, so that many of the phenomena
produced by continental ice could not be explained. Professor
Fairchild says, as to this aspect: "More has been learned of the
structure, behavior, and work of our ancient ice sheets by the study
of the Alaskan glaciers during the last ten years, and especially by
the study of the Greenland ice cap during the last four years, than by
all the study of the Alpine glaciers for the seventy years since they
have been observed." Prominent among those who have worked in this
field are the names of Professors Chamberlain and Salisbury in
Greenland, and Professors H. F. Reid and I. C. Russell in Alaska;
other important contributors are Prof. W. P. Blake, the pioneer
geologist in Alaska, 1867; Dall and Baker, who discovered and named
the Malaspina Glacier in 1874; and John Muir, 1878, for whom the Muir
Glacier was named; Wright, Baldwin, Schwatka, Libbey, and others, and
Barton and Tarr in Greenland.
Professor Russell, in 1891, recognized and named a type of glacier
that was before unknown. In his studies on the Malaspina he found a
condition that does not occur, so far as yet observed, anywhere else
than on the northwest coast of America; this is where a number of
mountain glaciers debouch upon a low, flat coast plain, and unite to
form a great sluggishly moving sheet of ice. This particular
development he called the Piedmont type.
In closing his address, Professor Fairchild remarks that the word
"theory," as applied to the glacial origin of the drift and its
phenomena, may and should now be abandoned. The subject has passed
beyond the stage of theory, and is as well understood and as clearly
established as the volcanic origin of the cone of Vesuvius or the
sedimentary origin of stratified rocks.
* * * * *
In the center of the artificial platforms or platform
mounds, characteristic of many of the ancient Peruvian
towns, Mr. Bandelier has observed features that recall
forcibly the New Mexican Indian custom of giving to each
inanimate object its heart. In some instances, says Mr. F.
W. Hodge, in his paper, round columns formed a kind of an
interior niche; in others, a small chamber contained urns or
jars with maize meal. A remarkable and very significant
feature was observed by the explorer in a partly ruined
mound at Chanchan. The core of this structure when opened
showed two well-preserved altars of adobe. In such interior
apartments, figurines of metal, clay, or wood are almost
invariably found; and the materially valuable finds made in
Peruvian ruins in earlier times came from the "heart" of one
or the other of the artificial elevations described.
MODERN STUDIES OF EARTHQUAKES.
BY GEORG GERALAND.
The investigation of earthquakes, seismology, has become in the
present day an independent subject of scientific interest. In lands
where earthquakes are frequent, as in Italy and Japan, seismic
observations have been officially systematized over the whole country,
with central and branch stations at which the work is never still. A
net of seismic observations of all nations is being more and more
closely woven over the whole earth, and there are yearly and monthly
collations of observations of even the slightest shocks. Seismic
literature is, therefore, nearly inexhaustible, and theory and praxis
are in constant vogue; in short, seismics has grown to be a separate
branch of science, and to demand independent treatment, calling for
the energy and labor of many students. What gives it so great
importance? What is the condition of our present knowledge and its
history? What will be reached in the future through the competition of
the nations? These questions possess a high scientific as well as
culture-historical interest. We here attempt to answer them.
The first really scientific description of an earthquake--that of
Lisbon--with its far-reaching accompanying phenomena, was the work of
the greatest contemporary thinker, Kant, and it is not too much to say
that his paper opened a new epoch in the knowledge of earthquakes.
That terrible event and the extreme terror which it caused everywhere
were followed in 1783 by the likewise extremely destructive earthquake
of Calabria. The attention of the people was thus directed to this
mysterious mighty activity of the earth, and was kept especially
lively in Italy, the country of Europe most subject to earthquakes.
The newly rising science of geology therefore found in the last third
of the last century in these phenomena a problem of prominent
importance. Geologists were the first to apply themselves to seismic
studies, as the most widely current explanation of the phenomena is
still a geological one. The scientific interest of the question
prevailed over the practical. More attentive observation was given to
earthquakes, the accounts of them scattered through the ancient
chronicles were collated, and the already very numerous seismic notes
of great earthquake manifestations--such as those by Hoff, Perry,
Mallet, Volger, Fuchs, etc.--constituted a very important factor in
the study. One of the earliest results of the inquiry was to show that
directly perceptible earthquakes are not perceptible everywhere; that
they are most common on the great upfoldings of the earth's crust on
the mountain chains, such as the Andes, Alps, and Himalayas; and that,
further, they are connected with the shores of the Pacific, the
Antilles, and the Mediterranean, and with places also where great
breaches and various disturbances are evident; that they are at home
likewise in volcanoes; and that they are most frequent in the northern
hemisphere, and when the earth is nearest to the sun. The descriptions
of powerful shocks furnish us evidence of a double movement of the
earth's crust--an alternate up-and-down vibration and an often very
marked wave motion. The destruction which earthquake shocks and waves
inflict on buildings, and the remarkably rapid and wide spread of the
tremblings over the surface of the earth, have been very diligently
inquired into; and when, in 1856, Naples and Calabria were visited by
a great earthquake, an English investigator, Robert Mallet, made a
full study of it, and believed that by comparing the direction of the
rents in walls and buildings, which were assumed to correspond with
that of the tremblings, he could identify the focus of the shocks in
the earth's interior, and the course of the wave movement over its
surface--a view which has long prevailed in seismology. Still more
important was the work of the geologist Karl von Seebach, of
Göttingen, on the great earthquake in central Germany, which kept the
northern part of the plains of the upper Rhine, around Mayence,
Grossgerau, and Darmstadt, disturbed for several years after 1869. Von
Seebach's chief effort was to obtain the most exact data possible as
to the time of the beginning of the shocks from as many places as
possible, from which he might deduce the spot where the shocks began
and were strongest, the epicenter which lay directly over the point in
the earth's interior where the movement originated. From them he also
deduced a series of localities where the shocks were simultaneous and
of equal intensity, which could be connected by certain nearly
circular lines called _homoseists_. As the distance of these from the
epicenter increases, the undulations take place later and are weaker,
and facts may be thus furnished from the velocity of propagation of
the shocks can be computed. The observations are also important
because von Seebach undertook through a simple mathematical
calculation to determine from them the situation of the forces of the
subterranean point where the undulations originated.
With these investigations, the process of annihilating time and space
by steam and the applications of electricity was also going on. By the
effect of this great event, the conditions of earthquake investigation
were revolutionized. A comparative study of the phenomena, fundamental
and essential to a science of seismology, on the basis of material
furnished from all the regions of the earth, was rendered possible. An
earthquake service was organized in Japan, by J. Milne, of England;
one had already been organized for a considerable time in Italy, and
the results obtained at the two places of observation so widely
separated corresponded. Japanese, Indian, and American earthquakes
could be simultaneously studied in Italy, Russia, Germany, and
England; and thus a new, hitherto undeveloped field was gained, the
scope of which has already extended far beyond its merely geological
aspect.