Chapter V: Antiquity of the Paleolithic Age.1

Interest in the Antiquity of man—Connected with the Glacial
Age—The Subject Difficult—Proofs of a Glacial Age—State of
Greenland to-day—The Terminal Moraine—Appearance of the North
Atlantic—Interglacial Age—Causes of the Glacial Age—Croll’s
Theory—Geographical causes—The two theories not Antagonistic—The
date of the Glacial Age—Probable length of the Paleolithic
Age—Time since the close of the Glacial Age—Summary of results.

As we have already remarked, geological periods give us no
insight as to the actual passage of years. To say that man lived
in the Glacial Age, and that we have some faint traces of his
presence in still earlier periods, after all conveys to our minds
only vague ideas of a far-away time. The more a geologist studies
the structure of the earth, the more impressed is he with the
magnitude of the time that must have passed since “The
Beginning.” At present, however, there are no means known of
accurately measuring the time that has passed. It is just as well
that it is so, since, were it known, the human mind would be
utterly incapable of comprehending it. But as to the antiquity of
man, it is but natural that we should seek more particularly to
solve the problem and express our answer in some term of years.

Now, we have seen that the question of the antiquity of man is
intimately connected with that of the Glacial Age. That is to
say, the relics of man as far as we know them in Europe, are
found under such circumstances that we feel confident they are
not far removed from the period of cold. For it will be found
that those conservative scholars who do not think that man
preceded the Glacial Age, or inhabited Europe during the long
course of years included in that period, do think he came into
Europe as soon as it passed away. So, in any case, if we can
determine the date of the Glacial Age, we shall have made a most
important step in advance in solving the problem of the antiquity
of man himself. So it seems to us best to go over the subject of
the Glacial Age again, and see what conclusions some of our best
thinkers have come to as to its cause, when it occurred, and
other matters in relation to it.

It is best to state frankly at the outset that this topic is one
of the great battle-grounds of science to-day, and that there are
as yet but few points well settled in regard to it. One needs but
attempt to read the literature on this subject to become quickly
impressed with the necessity of making haste slowly in forming
any conclusions. He must invoke the aid of the astronomer,
geologist, physical-geographer, and physicist. Yet we must not
suppose that questions relating to the Glacial Age are so
abstruse that they are of interest only to the scholar. On the
contrary, all ought to be interested in them. They open up one of
the most wonderful chapters in the history of the world. They
recall from the past a picture of ice-bound coasts and countries
groaning under icy loads, where now are harbors enlivened by the
commerce of the world, or ripening fields attesting the vivifying
influence of a genial sun. Let us, therefore, follow after the
leaders in thought. When we come to where they can not agree we
can at least see what both sides have to say.

Somewhat at the risk of repetition, we will try and impress on
our readers a sense of the reality and severity of the Glacial
Age. There is danger in regarding this as simply a convenient
theory that geologists have originated to explain some puzzling
facts, that it is not very well founded, and is liable to give
way any day to some more ingenious explanation. On the contrary,
this whole matter has been worked out by very careful scholars.
“There is, perhaps, no great conclusion in any science which
rests upon a surer foundation than this, and if we are to be
guided by our reason at all in deducting the unknown from the
known, the past from the present, we can not refuse our assent to
the reality of the Glacial Age of the Northern Hemisphere in all
its more important features.2 At the present day glaciers do
exist in several places on the earth. They are found in the Alps
and the mountains of Norway, and the Caucasus, in Europe. The
Himalaya mountains support immense glaciers in Asia; and in
America a few still linger in the more inaccessible heights of
the Sierra Nevada. It is from a study of these glaciers, mainly
however, those of the Alps, that geologists have been enabled to
explain the true meaning of certain formations they find in both
Europe and America, that go by the name of drift.

When in an Alpine valley we come upon a glacier, filling it from
side to side, there will be noticed upon both sides a long train
of rock, drift, and other _débris_ that have fallen down upon its
surface from the mountain sides. If two of these ice-rivers unite
to form one glacier, two of these trains will then be borne along
in the middle of the resulting glacier. As this glacier continues
down the valley, it at length reaches a point where a further
advance is rendered impossible by the increased temperature
melting the ice as fast as it advances. At this point the train
of rocks and dirt are dumped, and of course form great mounds,
called moraines. The glacier at times shrinks back on its rocky
bed and allows explorers to examine it.

In such cases they find the rocks smoothed and polished, but here
and there marked with long grooves and striæ. These points are
learned from an examination of existing glaciers. Further down
the valley, where now the glaciers never extend, are seen very
distinctly the same signs. There are the same moraines, striated
rocks, and bowlders that have evidently traveled from their home
up the valley. The only explanation possible in this case is that
once the glaciers extended to that point in the valley.

It required a person who was perfectly familiar with the behavior
of Alpine glaciers, and knew exactly what marks they left behind
in their passage, to point out the proofs of their former
presence in Northern Europe and America, where it seems almost
impossible to believe they existed. Such a man was Louis Agassiz,
the eminent naturalist. Born and educated in Switzerland, he
spent nine years in researches among the glaciers of the
mountains of his native country. He proved the former wide
extension of the glaciers of Switzerland. With these results
before them, geologists were not long in showing that there had
once been glacial ice over a large part of Europe and North
America.

The proofs in this case are almost exactly the same as those used
to show that the ancient glaciers of Switzerland were once larger
than now. But as the great glaciers of the glacial age were many
times larger than any thing we know of at the present day, there
were of course different results produced.

For instance, the water circulating under Alpine glaciers is
enabled to wash out and carry away the mass of pulverized rock
and dirt ground along underneath the ice. But when the glaciers
covered such an enormous extent of country as they did in the
Glacial Age, the water could not sweep away this detritus, and so
great beds of gravel, sand, and clay would be formed over a large
extent of country. But to go over the entire ground would require
volumes; it is sufficient to give the results.

The interior of Greenland to-day is covered by one vast sea of
ice. Explorers have traversed its surface for many miles; not a
plant, or stone, or patch of earth is to be seen. In the Winter
it is a snow-swept waste. In the Summer streams of ice-cold water
flow over its surface, penetrating here and there by crevasses to
unknown depths. This great glacier is some twelve hundred miles
long, by four hundred in width.3 Vast as it is, it is utterly
insignificant as compared with the great continental glacier that
geologists assure us once held in its grasp the larger portion of
North America.

The conclusions of some of our best scholars on this subject are
so opposed to all that we would think possible, according to the
present climate and surroundings, that they seem at first
incredible, and yet they have been worked out with such care that
there is no doubt of the substantial truth of the results.

The terminal moraine of the great glacier has been carefully
traced through several States. We now know that one vast sea of
ice covered the eastern part of North America, down to about the
thirty-ninth parallel of latitude. We have every reason to think
that the great glacier, extending many miles out in the Atlantic,
terminated in a great sea of ice, rising several hundred feet
perpendicularly above the surface of the water. Long Island marks
the southern extension of this glacier. From there its temporal
moraine has been traced west, across New Jersey and Pennsylvania,
diagonally across Ohio, crossing the river near Cincinnati, and
thence west across Indiana and Illinois. West of the Mississippi
it bears off to the north-west, and finally passes into British
America.4

All of North America, to the north and northeast of this line,
must have been covered by one vast sea of ice.5 Doubtless, as in
Greenland to-day, there was no hill or patch of earth to be seen,
simply one great field of ice. The ice was thick enough to cover
from sight Mt. Washington, in New Hampshire, and must have been
at least a mile thick over a large portion of this area,6 and
even at its southern border it must in places have been from two
hundred to two thousand feet thick.7 This, as we have seen, is a
picture very similar to what must have been presented by Europe
at this time.8

Antarctic Ice Sheet.

The Northern Atlantic Ocean must have presented a dreary aspect.
Its shores were walls of ice, from which ever and anon great
masses sailed away as icebergs. These are startling conclusions.
Yet, in the Southern Hemisphere to-day is to be seen nearly the
same state of things. It is well-known that all the lands around
the South Pole are covered by a layer of ice of enormous
thickness. Sir J. A. Ross, in attempting to reach high southern
latitudes, while yet one thousand four hundred miles from the
pole, found his further progress impeded by a perpendicular wall
of ice one hundred and eighty feet thick. He sailed along that
barrier four hundred and fifty miles, and then gave up the
attempt. Only at one point in all that distance did the ice wall
sink low enough to allow of its upper surface being seen from the
mast-head. He describes the upper surface as an immense plain
shining like frosted silver, and stretching away as far as eye
could reach into the illimitable distance.9

The foregoing makes plain to us one phase of the Glacial Age.
Though it may not be quite clear what this has to do with the
antiquity of man, yet we will see, in the sequel, that it has
considerable. As to the periods of mild climate that are thought
by some to have broken up the reign of cold, we do not feel that
we can say any thing in addition to what has been said in a
former chapter.10

We might, however, say, that the sequences of mild and cold
climate are not as well made out in America as they seem to be in
Europe; or at least our geologists are more cautious as to
accepting the evidence as sufficient. And yet such evidences are
not wanting: as in Europe, at various places, are found layers of
land surfaces with remains of animals and plants, but both above
and below such surface soil are found beds of bowlder clay. These
offer undeniable evidence that animals and plants occupied the
land during temperate inter-glacial epochs, preceded and followed
by an Arctic climate, and ice-sheets like those now covering the
interior of Greenland, and the Antarctic Continent.11

We have thus, though somewhat at length, gone over the evidence
as to the reality and severity of the Glacial Age. It was during
the continuance of such climate that Paleolithic man arrived in
Europe, though it was not perhaps until its close. We must not
lose sight of the fact that our principal object at present is to
determine, if we can, a date for either the beginning or ending
of this extraordinary season of cold, and thereby achieve an
important step in determining the antiquity of man.

A moment’s consideration will show us that a period of cold
sufficient to produce over a large portion of the Northern
Hemisphere the results we have just set forth must have a cause
that is strange and far-reaching. It can not be some local cause,
affecting but one continent, since the effect produced is
observed as well in Europe as in America.

Every year we pass through considerable changes in climate. The
four seasons of the year seem to be but an annual repetition, on
a very small scale of course, of the great changes in the climate
of the earth that culminated in the Glacial Age; though we do not
mean to say, that periods of glacial cold come and go with the
regularity of our Winter. The changes in the seasons of the year
are caused by the earth’s position in its orbit, and its annual
revolution around the sun. It may be that the cause of the
Glacial Age itself is of a similar nature; in which case it is an
astronomical problem, and we ought, by calculation, to determine,
with considerable accuracy, dates for the beginning and ending of
this epoch.

Nothing is clearer than that great fluctuations of climate have
occurred in the past. Many theories have been put forth in
explanation. It has been suggested that it was caused by loss of
heat from the earth itself. That the earth was once a ball of
incandescent matter, like the sun, and has since cooled down, is
of course admitted. More than that, this process still continues;
and the time must come when the earth, having yielded up its
internal heat, will cease to be an inhabitable globe. But the
climate of the surface of the earth is not dependent upon the
heat of the interior. This now depends “according to the
proportion of heat received either directly or indirectly from
the sun; and so it must have been during all the ages of which
any records have come down to us.”12 Some have supposed that the
sun, traveling as it does through space, carrying the earth and
the other planets with him, might, in the course of ages, pass
through portions of space either warmer or colder than that in
which it now moves. When we come to a warm region of space, a
genial climate would prevail over the earth; but, when we struck
a cold belt, eternal Winter would mantle a large part of the
globe with snow and ice. This, of course, is simply guess-work.
No less than seven distinct causes have been urged; most of them
either purely conjectural, like the last, or manifestly
incompetent to produce the great results which we have seen must
be accounted for. But, amongst these, two causes have been
advanced—the one astronomical, the other geographical; and, to
the one or the other, the majority of scholars have given their
consent.

It will be no harm to see what can be said in favor of both
theories. So, we will ask the reader’s attention, as it is our
earnest desire to make as plain as possible a question that has
so much to do with our present inquiry. In the course of our
investigations, we can not fail to catch glimpses of wonderful
changes in far away times; and can not help seeing what labor is
involved in the solution of all questions relating to the same.13

Earth’s Orbit.

The earth revolves around the sun in an orbit called an ellipse.
This is not a fixed form, but slowly varies from year to year. It
is now gradually becoming circular. It will, however, not become
an exact circle. Astronomers assure us that, after a long lapse
of time, it will commence to elongate as an ellipse again. Thus,
it will continually change from an ellipse to an approximate
circle, and back again. In scientific language, the eccentricity
of, the earth’s orbit is said to increase and decrease.

In common language we would state that the shape of the path of
the earth around the sun was sometimes much more elongated and
elliptical than at others. The line drawn through the longest
part of an ellipse is called the major axis. Now the sun does not
occupy the center of this line, but is placed to one side of it;
or, in other words, occupies one focus of the ellipse. It will
thus be seen that the earth, at one time during its yearly
journey, is considerably nearer to the sun than at others. The
point where it approaches nearest the sun is called _Perihelion,_
and the point where it reaches the greatest distance from the sun
is called its _Aphelion._ It will be readily seen that the more
elliptical its orbit becomes the greater will be the difference
between the perihelion and aphelion distance of the sun. At
present the earth is about three millions of miles nearer the sun
in perihelion than in aphelion. But we must remember the orbit of
the earth is now nearly circular. There have been times in the
past when the difference was about thirteen millions of miles. We
must not forget to add, that the change in the shape of the
earth’s orbit is not a regular increase and decrease between
well-known extremes. It is caused by the attraction of the other
planets. It has been calculated at intervals of ten thousand
years for the last million years. In this way it has been found
that “the intervals between connective turning points are very
unequal in length, and the actual maximum and minimum values of
the eccentricity are themselves variable. In this way it comes
about that some periods of high eccentricity have lasted much
longer than others, and that the orbit has been more elliptical
at some epochs of high eccentricity than at others.”14 We have
just seen that the earth is nearer the sun at one time of the
year than at another. At present the earth passes its perihelion
point in the Winter of the Northern Hemisphere, and its aphelion
point in the Summer. We will for the present suppose that it
always reaches the points at the same season of the year. Let us
see if the diminished distance from the sun in Winter has any
thing to do with the climate.

If so, this effect will be greatly magnified during a period of
high eccentricity, such as the earth has certainly passed through
in the past. We will state first, that the more elliptical the
orbit becomes, the longer Summer we have, and the shorter Winter.
Astronomically, Spring begins the 20th of March, and Fall the 22d
of September. By counting the days between the epochs it will be
found that the Spring and Summer part of the year is seven days
longer than the Fall and Winter part. But if the earth’s orbit
becomes as highly eccentrical as in the past, this difference
would be thirty-six days.15

This would give us a long Spring and Summer, but a short Fall and
Winter. This in itself would make a great difference. We must
beer in mind, however, that at such a time as we are here
considering, the earth would be ten millions of miles nearer the
sun in Winter than at present. It would certainly then receive
more heat in a given time during Winter than at present.16 Mr.
Croll estimates that whereas the difference in heat received
during a given time is now one-fifteenth,17 at the time we are
considering it would be one-fifth. Hence we see that at such a
time the Winter would not only be much shorter than now, but at
the same time would be much milder.

These are not all the results that would follow an increase of
eccentricity. The climate of Europe and North America is largely
modified by those great ocean currents—the Gulf Stream and the
Japan current. Owing to causes we will not here consider, these
currents would be greatly increased at such a time. As a result
of these combined causes, Mr. Croll estimates that during a
period of high eccentricity the difference between Winter and
Summer in the Northern Hemisphere would be practically
obliterate. The Winter would not only be short, but very mild,
and but little snow would form, while the sun of the long
Summers, though not shining as intense as at present, would not
have to melt off a great layer of snow and ice, but the ground
became quickly heated, and so warmed the air. Hence, if Mr. Croll
be correct, a period of high eccentricity would certainly produce
a climate in the Northern Hemisphere such as characterized many
of the mild interglacial epochs as long as the earth passed its
perihelion point in Winter.

We have so far only considered the Northern Hemisphere. As every
one knows, while we have Winter, the Southern Hemisphere has
Summer. So at the very time we would enjoy the mild short
Winters, the Southern Hemisphere would be doomed to experience
Winters of greatly increased length and severity. As a
consequence, immense fields of snow would be formed, which, by
pressure, would be changed to ice, and creep away as a desolating
glacier. It is quite true that the short Summer sun would shine
with increased warmth, but owing to many causes it would not
avail to free the land from snow and ice.

As Mr. Geikie points out, “An increased amount of evaporation
would certainly take place, but the moisture-laden air would be
chilled by coming into contact with the vast sheets of snow, and
hence the vapor would condense into thick fogs and cloud the sky.
In this way the sun’s rays would be, to a large extent, cut off,
and unable to reach the earth, and consequently the Winter’s snow
would not be all melted away.” Hence it follows that at the very
time the Northern Hemisphere would enjoy a mild interglacial
climate, universal Spring, so to speak, the Southern Hemisphere
would be encased in the ice and snow of an eternal Winter.

But the earth has not always reached its perihelion point during
the Winter season of the Northern Hemisphere. Owing to causes
that we need not here consider, the earth reaches its perihelion
point about twenty minutes earlier each year, so if it now passes
its perihelion in Winter of the Northern Hemisphere, in about ten
thousand years from now it will reach it in Summer, and in
twenty-one thousand, years it will again be at perihelion in
Winter. But see what important consequences follow from this. If
during a period of high eccentricity we are in the enjoyment of
short mild Winters and long pleasant Summers, in ten thousand
years this would certainly be changed. Our Summer season would
become short and heated; our Winters long and intensely cold.
Year by year it would be later in the season before the sun could
free the land from snow, and at length in deep ravines and on
hill-tops the snow would linger through the brief Summer, and the
mild interglacial age will have passed away, and again the
Northern Hemisphere will be visited by snow and ice of a truly.
Glacial Age. If, therefore, a period of high eccentricity lasts
through the many thousand years, we must expect more than one
return of glacial cold interspersed by mild interglacial
climates.

We have tried in these last few pages to give a clear statement
of what is known as Croll’s theory of the Glacial Age. There is
no question but what the earth does thus vary in its position
with regard to the sun, and beyond a doubt this must produce some
effect on the climate, and we can truthfully state that the more
the complicated question of the climate of the earth is studied,
the more grounds do scholars find for affirming that indirectly
this effect must have been very great. And yet we can not say
that this theory is accepted as a satisfactory one even by the
majority of scholars. Many of those who do not reject it think it
not proven. Therefore, before interrogating the astronomer as to
the data of the Glacial Age, according to the terms of this
theory, let us see what other causes are, adduced; then we can
more readily accept or reject the conclusions as to the antiquity
of man which this theory would necessitate us to adopt.

The only other cause to which we can assign the glacial cold,
that is considered with any favor by geologists, is geographical;
that is to say, depending on the distribution of land and water.
Glaciers depend on the amount of snow-fall. In any country where
the amount of snow-fall is so great that it is not all evaporated
or melted by the Summer’s sun, and consequently increases from
year to year, glaciers must soon appear, and these icy rivers
would ere-long, flow away to lower levels. If we suppose, with
Sir Charles Lyell, that the lands of the globe were all to be
gathered around the equator, and the waters were gathered around
the poles, it is manifest that there would be no such a thing as
extremes of temperature, and it is, perhaps, doubtful whether ice
would form, even in polar areas.18 At any rate, no glaciers could
be formed, as there would be no land on which snow could gather
in great quantities.

If, however, we reverse this picture, and conceive of the land
gathered in a compact mass around the poles, shutting out the
water, but consider the equatorial region of the earth to be
occupied by the waters of the ocean, we would manifestly have a
very different scene. From the ocean moisture-laden winds would
flow over the polar lands. The snowfall would necessarily be
great. In short, we can not doubt but what all the land of the
earth would be covered with glaciers.19

Although these last conceptions are purely hypothetical, they
will serve the good purpose of showing the great influence that
the geographical distribution of land and water have on the
climate of a country. Of one thing, however, geologists have
become more and more impressed of late years. That is, that
continents and oceans have always had the same relative position
as now; that is to say, the continents have followed a definite
plan in their development. The very first part of North America
to appear above the waters of the primal sea clearly outlined the
shape of the future continent. Mr. Dana assures us that our
continent developed with almost the regularity of a flower. Prof.
Hitchcock also points out that the surface area of the very first
period outlined the shape of the continent. “The work of later
geological periods seems to have been the filling up of the bays
and sounds between the great islands, elevating the consolidated
mass into a continental area.”20 So it is not at all probable
that the lands of the globe were ever grouped, as we have here
supposed them.

This last statement is liable, however, to leave us under a wrong
impression; for although, as a whole, continental areas have been
permanent, yet in detail they have been subject to wonderful and
repeated changes. “Every square mile of their surface has been
again and again under water, sometimes a few hundred feet
deep—sometimes, perhaps, several thousand. Lakes and inland seas
have been formed and been filled up with sediment, and been
subsequently raised into hills, or even mountains. Arms of the
sea have existed, crossing the continent in various directions,
and thus completely isolating the divided portions for varying
intervals. Seas have become changed into deserts and deserts into
seas.”21

It has been shown beyond all question that North-western Europe
owes its present mild climate to the influence of the Gulf
Stream.22 Ocean currents, then, are a most important element in
determining the climate of a country. If we would take the case
of our hypothetical polar continent again, and, instead of
presenting a continuous coast line, imagine it penetrated by long
straits and fiords, possessing numerous bays, large inland seas,
and in general allowing a free communication with the ocean, we
are very sure the effect would be widely different.

Under these circumstances, says Mr. Geikie, the “much wider
extent of sea being exposed to the blaze of the tropical sun, the
temperature of the ocean in equatorial regions would rise above
what it is at present. This warm water, sweeping in broad
currents, would enter the polar fiords and seas, and everywhere,
beating the air, would cause warm, moist winds to blow athwart
the land to a much greater extent than they do at present; and
these winds thus distributing warmth and moisture, might render
even the high latitude of North Greenland habitable by civilized
man.” So we see that it is necessary to look for such
geographical changes as will interfere with the movements of
marine currents.

Now, it is easy to see that comparatively small geographical
changes would not only greatly interfere with these currents, but
might even cause them to entirely change their course. An
elevation of the northern part of North America, no greater in
amount than is supposed to have taken place at the commencement
of the Glacial Age, would bring the wide area of the banks of
Newfoundland far above the water, causing the American coast to
stretch out in an immense curve to a point more than six hundred
miles east of Halifax, and this would divert much of the Gulf
Stream straight across to the coast of Spain.23

Such an elevation certainly took place, and if continued
westward, Behring’s Strait would also have been closed. It is to
such northern elevations, shutting out the warm ocean currents,
that a great many geologists look for a sufficient explanation of
the glacial cold.

Prof. Dana says: “Increase in the extent and height of high
latitude lands may well stand as one cause of the Glacial Age.”
Then he points out how the rising of the land of Northern Canada
and adjacent territory, which almost certainly took place, “all a
sequel to the majestic uplift of the Tertiary, would have made a
glacial period for North America, whatever the position of the
ecliptic, or whatever the eccentricity of the earth’s orbit,
though more readily, of course, if other circumstances favored
it.”24

It may occur to some that if high northern lands be all that is
necessary for a period of cold, we ought to have had it in the
Miocene Age, when there was a continuous land connection between
the lands of high polar areas and both Europe and America, since
we know that an abundant vegetation spread from there, as a
center, to both these countries. But at that epoch circumstances
were different. The great North Temperate lands were in a
“comparatively fragmentary and insular condition.”25 There were
great inland seas in both Europe and Asia, through which powerful
currents would have flowed from the Indian Ocean to Arctic
regions.

Somewhat similar conditions prevailed in North America. The
western part was in an insular condition. A great sea extended
over this part of the country, joining the Arctic probably on the
north, through which heated water would pour into the polar sea.
And so, instead of a Glacial Age, we find evidence of a mild and
genial climate, with an abundant vegetation.

We thus see that there are two theories as to the cause of the
Glacial Age presented for our consideration. Both of them have
received the sanction of scholars eminent for their scientific
attainments. On inspection we see they are not antagonistic
theories. They may both be true for that matter, and all would
admit that whatever effect they would produce singly would be
greatly enhanced if acting together. Indeed, there are very good
reasons for supposing both must have acted in unison.

There seem to be very good reasons for not believing that the
eccentricity of the earth’s orbit, acting alone, produced the
glacial cold. If that were the case, then whenever the
eccentricity was great we should have a Glacial Age. Now, at some
period of time during the long-extended Tertiary Age we are
certain the eccentricity of the earth’s orbit became very great,
much more so, in fact, than that which is supposed to have
produced the cold of the Quaternary Age. But we are equally
certain there was no glacial epoch during this age.26 What other
explanation can we give for its non-appearance except that
geographical conditions were not favorable?

But, on the other hand, there are certain features connected with
the phenomena of the Glacial Age that seem very difficult of
explanation, if we suppose that geographical changes alone
produced them. We must remember that evidences of the former
presence of glaciers are found widely scattered over the earth.
We shall, therefore, have to assume an elevation not only for
America and Europe, but extend it over into Asia, and take in the
Lebanon Mountains, for they also show distinct traces of
glaciers. And this movement of elevation must also have affected
the Southern Hemisphere, the evidence being equally plain that at
the same comparatively late date glaciers crushed over Southern
Africa and South America.27 This is seen to prove too much.
Again, how can we explain the fact that some time during the
Glacial Age we had a submergence, the land standing several
hundred feet lower than now, but still remained covered with ice,
and over the submerged part there sailed icebergs and ice-rafts,
freighted with their usual _débris_? That such was the state of
things in Europe we are assured by some very good authorities.28

Neither do geographical causes afford an adequate explanation of
those changes of temperature that surely took place during the
Glacial Age. These last considerations show us how difficult it
is to believe that geographical causes could have produced the
Glacial Age.

We are assured that all through the geological ages the
continents had been increasing in size and compactness, and that
just at the close of the Tertiary Age they received a
considerable addition of land to the north. The astronomer also
informs us that at a comparatively recent epoch the eccentricity
of the earth’s orbit became very great. The conditions being
favorable, it is not strange that a Glacial Age supervened.

We have been to considerable length in thus explaining the
position of the scientific world in regard to the cause of the
Glacial Age. Our reason for so doing is that this age is, we
think, so connected with the Paleolithic Age of man, that it
seems advisable to have a clear understanding in regard to it.
What we have to say is neither new nor original. It is simply an
earnest endeavor to represent clearly the conclusions of some of
our best scholars on this subject, and we have tried to give to
each theory its due weight. Our conclusions may be wrong, but, if
so, we have the consolation of erring in very good company.

We have now gone over the ground and are ready to see what dates
can be given. Though the numbers we use seem to be very large
indeed, they are so only in comparison with our brief span of
life. They are insignificant as compared with the extent of time
that has surely rolled by since life appeared on the globe. Let
us, therefore, not be dismayed at the figures the astronomer sets
before us.29

About two hundred and fifty thousand years ago the earth’s path
around the sun was much the same as that of the present. No great
changes in climate were liable to take place at that time. During
the next fifty thousand years the eccentricity steadily
increased. Towards the end of that time all that was necessary to
produce a glacial epoch in the Northern Hemisphere was favorable
geographical causes, and that our earth should reach its point
nearest the sun in Summer. This it must have done when about half
that time had elapsed.

We can in imagination see what a slow deterioration of climate
took place. Thousands of years would come and go before the
change would be decisive. But a time must have at length arrived
when the vegetation covering the ground was such as was suited
only for high northern latitudes. The animals suited for warm and
temperate regions must have wandered farther south; others from
the north had arrived to take their place. We can see how well
this agrees with the changes of climate at the close of the
Pliocene Age. The snows of the commencing Glacial Age would soon
begin to fall, finally the sun would not melt them off of the
high lands, and mountain peaks, and so a Glacial Age would be
ushered in.

We have referred to the fact that the earth reaches its
perihelion point a little earlier each year, and, as a
consequence, we would have periods of mild climate alternating
the cold. This extended period of time, equal to twenty-one
thousand of our ordinary years, has been named the Great Year of
our globe. Mr. Wallace has pointed out some very good reasons for
thinking Mr. Croll’s theory must be modified on this point. He
thinks that when once a Glacial Age was fairly fastened on a
hemisphere, it would retain its grasp as long as the eccentricity
remained high, but whenever the Summer of the Great Year came to
that hemisphere, it would melt back the glacial ice for some
distance, but this area would be recovered by the ice when the
Winter of the Great Year supervened. These effects would be
different when the eccentricity itself became low. Then we would
expect the glacial conditions to vanish entirely when the Summer
of a Great Year comes on.30

As we have made the theoretical part of this chapter already too
long, we must hurry on. We can only say that this view is founded
on the fact that when a country was covered with snow and ice, it
had so to speak, a great amount of cold stored up in it, so much,
in fact, that it would not be removed by the sun of a new
geological Summer. This ought to be acceptable to such geologists
as are willing to admit the advance and retreat of the great
glacier, but yet doubt the fact of the interglacial mild climate.

But now to return to the question of time about two hundred and
twenty thousand years ago. Then the Northern Hemisphere,
according to this theory, was in the grasp of a Glacial Age.
According to Mr. Wallace, as long as the eccentricity remained
high, there could be no great amelioration of climate, except
along the southern border of the ice sheet, which might, for
causes named, vary some distance during the Great Year. Two
hundred thousand years ago the eccentricity, then very high,
reached a turning point. It then steadily, though gradually,
diminished for fifty thousand years; at that time the
eccentricity was so small, though considerably larger than at
present, that it is doubtful if it was of any service in
producing a change of climate.31 At that time, also, the Northern
Hemisphere was passing through the Summer season of the Great
Year. We ought, therefore, to have had a mild interglacial
season. Except in high northern latitudes the ice should have
disappeared. This change we would expect to find more marked in
Europe than in America.

We need only recall how strong are the evidences on this point.
Nearly all European writers admit at least one such mild
interval, and though not wanting evidence of such a period in
America, our geologists are much less confident of its
occurrence.

But from that point the eccentricity again increased. So when the
long flight of years again brought secular Winter to the Northern
Hemisphere, the glaciers would speedily appear, and as
eccentricity was again high, they would again hold the country in
their grasp. Fifty thousand years later, or one hundred thousand
years ago, it passed its turning point again; eighty thousand
years ago, it became so small that it probably ceased to effect
the climate. Since then it has not been very large. Twenty-five
thousand years ago it was less than it is now, but it is again
growing smaller. According to this theory, then, the Glacial Age
commenced about two hundred and twenty thousand years ago. It
continued, with one interruption of mild climate, for one hundred
and forty thousand years, and finally passed away eighty thousand
years ago.

What shall we say to these results? If true, what a wonderful
antiquity is here unfolded for the human race, and what a
wonderful lapse of time is included in what is known as the
Paleolithic Age! How strikingly does it impress upon our minds
the slow development of man! Is such an antiquity for man in
itself absurd? We know no reason for such a conclusion. Our most
eminent scholars nowhere set a limit to the time of man’s first
appearance. It is true, many of them do not think the evidence
strong enough to affirm such an antiquity, but there are no
bounds given beyond which we may not pass.

Without investigation some might reject the idea that man could
have lived on the earth one hundred thousand years in a state of
Savagism. If endowed with the attributes of humanity, it may seem
to them that he would long before that time have achieved
civilization. Such persons do not consider the lowliness of his
first condition and the extreme slowness with which progress must
have gone forward. On this point the geologists and the
sociologists agree. Says Mr. Geikie: “The time which has elapsed
from the close of the Paleolithic Age, even up to the present
day, can not for a moment compare with the aeons during which the
men of the old stone period occupied Europe.” And on this subject
Mr. Morgan says: “It is a conclusion of deep importance in
ethnology that the experience of mankind in Savagery was longer
in duration than all their subsequent experience, and that the
period of Civilization covers but a fragment of the life of the
race.”32 The time itself, which seems to us so long, is but a
brief space as compared with the ages nature has manifestly
required to work out some of the results we see before us every
day. We are sure, but few of our scholars think this too liberal
an estimate. All endeavor to impress on our minds that the
Glacial Age is an expression covering a very long period of time.

As to the time that has elapsed since the close of the Glacial
Age there is some dispute, and it may be that we will be forced
to the conclusion that the close of the Glacial Age was but a few
thousand years ago. Mr. Wallace assures us, however, that the
time mentioned agrees well “with physical evidence of the time
that has elapsed since the cold has passed away.”33

Difficulties are, however, urged by other writers. We can see at
once that as quick as the glaciers are removed the denuding
forces of nature, which are constantly at work, would begin to
rearrange the _débris_ left behind on the surface, and in the
course of a few thousand years must effect great changes. Now, in
some cases the amount of such change is so small that geologists
are reluctant to believe a vast lapse of time has occurred since
the glaciers withdrew. Mr. Geikie tells us of some moraines in
Scotland that they are so fresh and beautiful “that it is
difficult to believe they can date back to a period so vastly
removed as the Ice Age is believed to be.”34 In our own country
this same sort of evidence is brought forward, and we are given
some special calculations going to show that the disappearance of
the glaciers was a comparatively recent thing.35

It will be seen that these conclusions are somewhat opposed to
the results previously arrived at. In explanation Mr. Geikie
thinks the cases spoken of in Scotland were not the moraines of
the great glaciers, but of a local glacier of a far later date.
He thinks that the climate, while not severe enough to produce
the enormous glaciers of early times, was severe enough to
produce local glaciers still in Scotland.36 It is possible that a
similar explanation may be given for the evidence adduced in the
United States. We can only state that, according to the
difference in climate between the eastern and western sides of
the Atlantic Ocean, when the climate was severe enough to produce
local glaciers in Scotland, it would produce the same effect over
a large part of eastern United States down to the latitude of New
York City.37 And while it is true there would not be as much
difference in climate on the two sides of the Atlantic in Glacial
times as at present, since the Gulf Stream, on which such
difference depends would then have less force, still it was not
entirely lacking, and the difference must have been
considerable.38

Prof. Hitchcock has made a suggestion that whereas we know a
period of several months elapses after the sun crosses the
equator before Summer fairly comes on, so it is but reasonable to
suppose that a proportionate length of time would go by after the
eccentricity of the earth’s orbit became small, before the
Glacial Age would really pass away. He accordingly suggests it
may have been only about forty thousand years since the glaciers
disappeared.39

At the close of the Glacial Age Paleolithic man vanished from
Europe. This, therefore, brings us to the conclusion of our
researches into what is probably the most mysterious chapter of
man’s existence on the earth.

It may not come amiss to briefly notice the main points thus far
made in our investigation of the past. As to the epoch of man’s
first appearance, we found he could not be expected to appear
until all the animals lower than he had made their appearance.
This is so because the Creator of all has apparently chosen that
method of procedure in the development of life on the globe.
According to our present knowledge, man might have been living in
the Miocene Age, and with a higher degree of probability in the
Pliocene. But we can not say that the evidence adduced in favor
of his existence at these early times is satisfactory to the
majority of our best thinkers. All agree that he was living in
Europe at the close of the Glacial Age, and we think the evidence
sufficient to show that he preceded the glaciers, and that as a
rude savage he lived in Europe throughout the long extended
portion of time known as the Glacial Age.

We also found evidence of either two distinct races of men
inhabiting Europe in the Paleolithic Age, or else tribes of the
same race, widely different in time and in culture. The one
people known as the men of the River Drift apparently invaded
Europe from Asia, along with the species of temperate animals now
living there. This people seem to have been widely scattered over
the earth. The race has probably vanished away, though certain
Australian tribes may be descendants of them. They were doubtless
very low in the scale of humanity, having apparently never
reached a higher state than that of Lower Savagism. The second
race of men inhabiting Europe during the Paleolithic Age were the
Cave-dwellers. They seem to have been allied to the Eskimos of
the North. They were evidently further advanced than the Drift
men, but were still savages.

The Paleolithic Age in Europe seems to have terminated with the
Glacial Age. But we are not to suppose it came to an end all over
the earth at that time. On the contrary, some tribes of men never
passed beyond that stage. When the light of civilization fell
upon them they were still in the culture of the old Stone Age. We
are to notice that in such cases the tribes thus discovered were
very low in the scale. The probable data for the Paleolithic Age
have formed the subject of this chapter. While claiming in
support of them the opinions of some eminent scholars, we freely
admit that it is not a settled question, but open to very grave
objections, especially the date of the close of the Glacial Age,
which seems to have been comparatively recent, at least in
America. We think, however, that these objections will yet be
harmonized with the general results. Neither is this claimed to
be an exhaustive presentation of the matter. It is an outline
only—the better to enable us to understand the mystery connected
with the data of Paleolithic man.

In these few chapters we have been dealing with people, manners,
arid times, of which the world fifty years ago was ignorant. Many
little discoveries, at first apparently disconnected, are
suddenly brought into new relation, and behold, ages ago, when
the great continents were but just completed, races of men, with
the stamp of humanity upon them, are seen filling the earth. With
them were many great animals long since passed away. The age of
animals was at an end. That of man had just begun.

The child requires the schooling of adversity and trial to make a
complete man of himself, and it is even so with races of men. Who
can doubt that struggling up from dense ignorance, contending
against adverse circumstances, compelled to wage war against
fierce animals, sustaining life in the midst of the low
temperature which had loaded the Northern Hemisphere with snow
and ice, had much to do in developing those qualities which
rendered civilization possible.

As to the antiquity of man disclosed in these chapters, the only
question that need concern us is whether it is true or not.
Evidence tending to prove its substantial accuracy should be as
acceptable as that disproving it. No great principle is here at
stake. The truth of Divine Revelation is in no wise concerned.
There is nothing in its truth or falsity which should in any way
affect man’s belief in an overruling Providence, or in an
immortality beyond the grave, or which should render any less
desirable a life of purity and honor. On the contrary, we think
one of the greatest causes of thanksgiving mortals have is the
possession of intellectual powers, which enable us to here and
there catch a glimpse of the greatness of God’s universe, which
the astronomer at times unfolds to us; or, to dimly comprehend
the flight of time since “The Beginning,” which the geologist
finds necessary to account for the stupendous results wrought by
slow-acting causes.

It seems to us eminently fitting that God should place man here,
granting to him a capacity for improvement, but bestowing on him
no gift or accomplishment, which by exertion and experience he
could acquire; for labor is, and ever has been, the price of
material good. So we see how necessary it is that a very extended
time be given us to account for man’s present advancement.
Supposing an angel of light was to come to the aid of our feeble
understanding, and unroll before us the pages of the past, a past
of which, with all our endeavors, we as yet know but little. Can
we doubt that, from such a review, we would arise with higher
ideas of man’s worth? Our sense of the depths from which he has
ascended is equated only by our appreciation of the future
opening before him. Individually we shall soon have passed away.
Our nation may disappear. But we believe our race has yet but
fairly started in its line of progress; time only is wanted. We
can but think that that view which limits man to an existence
extending over but a few thousand years of the past, is a
belittling one. Rather let us think of him as existing from a
past separated from us by these many thousand years; winning his
present position by the exercise of God-given powers.

REFERENCES

The manuscript of this chapter was submitted to Prof. G. F.
Wright, of Oberlin, for criticism.

Wallace’s “Island Life,” p. 113.

Nordenskiold’s “American Journal of Science,” vol. 110, p. 58.

Wright’s “Studies in Science and Religion,” p. 307, where a map
of this moraine is given.

There is, however, a small area in the south-west part of
Wisconsin where, for some reason, the ice passed by.

Dane’s “Manual of Geology,” p. 538.

Wright’s “Studies in Science and Religion,” p. 308.

“Men of the Drift,” p. 71.

Geikie’s “Great Ice Age,” p. 93.

“Men of the River Drift.”

Abbott’s “Primitive Industry,” p. 545; Quoted from “Geology of
Minnesota.” Report, 1877, p. 37.

Geikie’s “Great Ice Age,” p. 97.

The astronomical theory, which we will first examine, was first
enunciated by Mr. Croll, following a suggestion of the
astronomer Adhemer. Mr. Croll’s views were set forth in many
able papers, and finally gathered into a volume entitled
“Climate and Time in their Geological Relation.” The ablest
defense of these views is that by Mr. James Geikie, in his
works “The Great Ice Age,” and “Prehistoric Europe.”

Geikie’s “Great Ice Age,” p. 114.

Lubbock’s “Prehistoric Times,” p. 420, Table 4.

Ibid., Table 5.

Geikie’s “Great Ice Age,” p. 123.

Wallace’s “Island Life,” p. 143.

Ibid., p. 124.

“Geology of New Hampshire,” Vol. II, p. 5.

Wallace’s “Island Life,” p. 99.

Geikie’s “Great Ice Age,” p. 103.

Wallace’s “Island Life,” p. 149. Hitchcock’s “Geology of New
Hampshire,” Vol. II, p. 7, gives a map showing what immense
areas in that section would be raised to the surface by a raise
of three hundred feet.

_American Journal of Science,_ 1871, p. 329.

Wallace’s “Island Life,” p. 184.

Wallace’s “Island Life,” p. 182.

Ibid., p. 157 and note. Prof. Wright thinks this statement
doubtful. He refers to the date of the Glacial Age in the
Southern Hemisphere.

Wallace’s “Island Life,” p. 200; Dawkins’s “Early Man in
Britain,” p. 119; Geikie’s “Great Ice Age,” p. 256;
Quatrefages’s “Human Species,” p. 288.

For these results, see McFarland’s Calculations in “American
Journal of Science,” 1880, p. 105.

“Island Life,” p. 153.

See chart, p. 124, Wallace’s “Island Life.”

“Ancient Society,” p. 39.

“Island Life,” p. 201.

“Prehistoric Europe,” p. 312.

On this point consult Wright’s “Studies in Science and
Religion,” pp. 232-347; also Prof. Lewis in “Primitive
Industry,” pp. 547-551.

“Prehistoric Europe,” p. 560.

See any isothermal map.

Wallace’s “Island Life,” p. 154, note.

“Geology of New Hampshire,” Vol. III, p. 327, referred to in
Wright’s “Studies in Science and Religion,” p. 327.