_ALPINE AND ARCTIC PLANTS IN CONNECTION WITH GEOLOGICAL HISTORY._
The group of the White Mountains is the culminating point of the
northern division of the great Appalachian range, extending from
Tennessee to Gaspé in a south-west and north-east direction, and
constituting the breast bone of the North American continent. This
great ridge or succession of ridges has its highest peaks near its
southern extremity, in the Black Mountains; but these are little
higher than their northern rivals, which at least hold the undisputed
distinction of being the highest hills in north-eastern America. As
Guyot[189] has well remarked, the White Mountains do not occur in
the general line of the chain, but rather on its eastern side. The
central point of the range, represented by the Green Mountains and
their continuation, describes a great curve from Gaspé to the valley
of the Hudson, and opposite the middle of the concave side of this
curved line towers the almost isolated group of the White Hills. On the
other side is the narrow valley of Lake Champlain, and beyond this the
great isolated mass of the Adirondack Mountains, nearly approaching in
the altitude of their highest peaks, and greatly exceeding in their
geological age, the opposite White Mountain group. The Appalachian
range is thus, in this part of its course, supported on either side by
outliers higher than itself. The dense grouping of mountains in this
region is due to the resistance offered by the old Adirondack mass
to the westward thrust of the Atlantic and the subsequent piling up
against this mass of the ridges of palæozoic sediments. Southward of
this the Atlantic thrust has driven these ridges back in a great bend
to the westward.
[189] _Silliman's Journal._
My present purpose is not to give a general geographical or geological
sketch of the White Mountains, but to direct attention to the
vegetation which clothes their summits, and its relation to the history
of the mountains themselves. For this purpose I may first shortly
describe the appearances presented in ascending the highest of them,
Mount Washington, and then turn to the special points to which these
notes relate.
In approaching Mount Washington by the Grand Trunk Railway, the
traveller has ascended from the valley of the St. Lawrence to a height
of 802 feet at the Alpine House at Gorham. Thence, in a distance of
about eight miles along the bank of the Peabody River, to the Glen
House, he ascends to the elevation of 1,632 feet above the sea; and it
is here, or immediately opposite the Glen House, that the actual ascent
begins. The distance from the Peabody River, opposite the hotel, to
the summit is nine miles, and in this distance we ascend 4,656 feet,
the total height being 6,288 feet above the sea.[190] Formerly only a
bridle path led up this ascent; but now access can be had to the summit
by carriage roads and by rail.
[190] According to Guyot, but some recent surveys make it a little
higher.
These royal roads to the summit are, however, too democratic for the
taste of some visitors, who mourn the olden days of ponies, guides and
adventures; and though they give an excellent view of the geological
structure of the mountain, they do not afford a good opportunity for
the study of the alpine flora, which is one of the chief attractions
of Mount Washington. For this reason, though I availed myself of the
new road for gaining a general idea of the features of the group,
I determined to ascend by Tuckerman's Ravine, a great chasm in the
mountain side, named in honour of the indefatigable botanist of the
North American lichens.[191] I was aided in this by the kindness of a
gentleman of Boston, well acquainted with these hills, and passionately
fond of their scenery.[192] Our party, in addition to this gentleman
and myself, consisted of two ladies, two children, and two experienced
guides, whose services were of the utmost importance, not only in
indicating the path, but in removing windfalls and other obstructions,
and in assisting members of the party over difficult and dangerous
places.
[191] Peck, Bigelow and Booth were the early botanical explorers of the
White Mountains; though Pursh was the first to determine some of the
more interesting plants, and Oakes and Tuckerman deserve honourable
mention, as the most thorough modern explorers.
[192] Mr. Raymond.
We followed the carriage road for two miles, and then struck off to the
left by a bridle path that seemed not to have been used for several
years the gentlemen and guides on foot, the ladies and children mounted
on the sure-footed ponies used in these ascents. Our path wound around
a spur of the mountain, over rocky and uneven ground, much of the rock
being mica slate, with beautiful cruciform crystals of andalusite,
which seemed larger and finer here than in any other part of the
mountain which I visited. At first the vegetation was not materially
different from that of the lower grounds, but as we gradually ascended
we entered the "evergreen zone," and passed through dense thickets of
small spruces and firs, the ground beneath which was carpeted with
moss, and studded with an immense profusion of the delicate little
mountain wood sorrel (_Oxalis acetosella_), a characteristic plant of
wooded hills on both sides of the Atlantic, and which I had not before
seen in such profusion since I had roamed on the hills of Lochaber
Lake in Nova Scotia. Other herbaceous plants were rare, except ferns
and club mosses; but we picked up an aster (_A. acuminatus_), a golden
rod (_Solidago thyrsoidea_), and the very pretty tway blade (_Listera
cordata_), a species[193] very widely distributed throughout British
America.
[193] _L. macrophylla_ Pursh (Macoun).
In ascending the mountain directly, the spruces of this zone gradually
degenerate, until they present the appearance of little gnarled
bushes, flat on top and closely matted together, so that except where
paths have been cut, it is almost impossible to penetrate among them.
Finally, they lie flat on the ground, and become so small that, as
Lyell remarks, the reindeer moss may be seen to overtop the spruces.
This dwarfing of the spruces and firs is the effect of adverse
circumstances, and of their struggle to extend their range toward the
summit. Year by year they stretch forth their roots and branches,
bending themselves to the ground, clinging to the bare rocks, and
availing themselves of every chasm and fissure that may cover their
advance; but the conditions of the case are against them. If their
front advances in summer, it is driven back in winter, and if in a
succession of mild seasons they are able to gain a little ground, less
favourable seasons recur, and wither or destroy the holders of their
advanced positions. For thousands of years the spruces and firs have
striven in this hopeless escalade, but about 4,000 feet above the sea
seems to be the limit of their advance, and unless the climate shall
change, or these trees acquire a new plasticity of constitution, the
genus _Abies_ can never displace the hardier alpine inhabitants above,
and plant its standard on the summit of Mount Washington.
I was struck by the similarity of this dwarfing of the upper edges of
the spruce woods, to that which I have often observed on the exposed
northern coasts of Cape Breton and Prince Edward Island, where the
woods often gradually diminish in height toward the beach or the edge
of a cliff, till the external row of plants clings closely to the soil,
or rises above it only a few inches. The causes are the same, but the
appearance is more marked on the mountain than on the coast. It is in
miniature a picture of the gradual dwarfing of vegetation in the great
barren grounds of Arctic America.
On the path which we followed, before we reached the upper limit
of trees, we arrived at the base of a stupendous cliff, forming the
termination of a promontory or spur of the mountain, separating
Tuckerman's Ravine from another deep depression known as the Great
Gulf. From the top of this precipice poured a little cascade, that lost
itself in spray long before it touched the tops of the trees below. The
view at this place was the most impressive that it was my fortune to
see in these hills.
Opposite the mouth of the Great Gulf, and I suppose at a height of
about 3,000 feet, is a little pond known as Hermit Lake. It is nearly
circular, and appears to be retained by a ridge of stones and gravel,
perhaps an old moraine or sea beach. On its margin piped a solitary
sandpiper, a few dragon flies flitted over its surface, and tadpoles in
the bottom indicated that some species of frog dwells in its waters.
High overhead, and skirting the edges of the precipices, soared an
eagle, intent, no doubt, on the hares that frequent the thickets of the
ravines.
Before we reached Hermit Lake we had been obliged to leave our horses,
and now we turned aside to the left and entered Tuckerman's ravine,
where there is no path, but merely the bed of a brook, whose cold clear
water tumbles in a succession of cascades over huge polished masses
of white gneiss, while on both sides of it the bottom of the ravine
is occupied by dense and almost impenetrable thickets of the mountain
alder (_Alnus viridis_).
Tuckerman's Ravine has been formed originally either by a subsidence
of a portion of the mountain side, or by the action of the sea. It
is, like most of the ravines and "gulfs" of these hills, a deep cut
or depression bounded by precipitous sides and terminating at the top
in a similarly precipitous manner. It must at one period have been in
part filled with boulder clay, steep banks of which still remain in
places on its sides; and extensive landslips have occurred, by which
portions of the limiting cliffs have been thrown toward the centre of
the valley, in large piles of angular blocks of gneiss and mica slate,
in the spaces between which grow gnarled birches and spruces that must
be used as ladders and bridges whereby to scramble from block to block,
by every one who would cross or ascend one of these rivers of stones.
These "gulfs" of the White Mountains are similar to the "cirques" of
the Alps, and various explanations have been given of their origin. To
me they have always appeared to be of the same nature with the "chines"
or bays with precipitous ends seen on rocky coasts, and which are
produced by the action of the surf on the softer beds or veins of rock.
They testify to the raging of the waves for long ages against the sides
of what are now lofty mountains. This, we know, must have occurred in
the great Pleistocene submergence; but in mountains so old as those now
in question, it may have in part been effected in previous periods.
At the head of the ravine we paused to rest, to admire the wild
prospect presented by the ravine and its precipitous sides, and to
collect the numerous plants that flower on the surrounding slopes and
precipices. Here, on the 19th of August, were several large patches of
snow, one of them about a hundred yards in length. From the precipice
at the head of the ravine poured hundreds of little rills, and several
of them collecting into a brook, had excavated in the largest mass of
snow a long tunnel or cavern with an arched and groined roof. Under the
front of this we took our mid-day meal, with the hot August sun pouring
its rays in front of us, and icy water gurgling among the stones at our
feet. Around the margin of the snow the vegetation presented precisely
the same appearances which are seen in the low country in March and
April, when the snow banks have just disappeared--the old grass
bleached and whitened, and many perennial plants sending up blanched
shoots which had not yet experienced the influence of the sunlight.
The vegetation at the head of this ravine and on the precipices that
overhang it, presents a remarkable mixture of lowland and mountain
species. The head of the ravine is not so high as the limit of trees
already stated, but its steep sides rise abruptly to a plateau of 5,000
feet in height, intervening between Mount Washington and Mount Munro,
and on which are the dark ponds or tarns known as the Lakes of the
Clouds, forming the sources of the Amonoosook river, which flows in
the opposite direction. From this plateau many alpine plants stretch
downward into the ravine, while lowland plants, availing themselves
of the shelter and moisture of this _cul-de-sac_, climb boldly upward
almost to the higher plateau. Other species again occur here, which
are found neither on the exposed alpine summits and ridges, nor in
the low country. Conspicuous among the hardy climbers are two coarse
and poisonous weeds of the river valleys, that look like intruders
into the company of the more dwarfish alpine plants;--the cow parsnip
(_Heracleum lanatum_) and the white hellebore (_Veratrum viride_).
Both of these plants were seen struggling up through the ground at the
margin of the snow, and climbing up moist hollows almost to the tops
of the precipices. Some specimens of the latter were crowded with the
infant caterpillars of a mountain butterfly or moth. Less conspicuous,
and better suited to the surrounding vegetation, were the bluets
(_Oldenlandia cœrulea_), now in blossom here, as they had been months
before in the low country, the dwarf cornel (_Cornus Canadensis_) and
the twin-flower (_Linnæa borealis_), the latter reaching quite to
the plateau of the lake of the Clouds, and entering into undisputed
companionship with the truly alpine plants, though it is also found at
Gorham, 4,000 feet lower.
Of the plants which seemed to be confined, or nearly so, to the upper
part of the ravine, one of the most interesting was the northern
painted cup (_Castelleia septentrionalis_), a plant which abounds on
the coast of Labrador, and extends thence through all Arctic North
America to the Rocky Mountains, and is perhaps identical with the _C.
Sibirica_ of Northern Asia and the _C. pallida_ of Northern Europe.
Large beds of it were covered with their pale yellow blossoms on the
precipitous banks overhanging the head of the ravine. With the painted
cup, and here alone, was another beautiful species of a very different
order, the northern green orchis (_Platanthera hyperborea_), a plant
which occurs, though rarely, in Canada, but is more abundant to the
northward. Here also occurred Peck's geum (_G. radiatum_, var.),
_Arnica mollis_, and several other interesting plants.
Of the alpine plants which descend into the ravine, the most
interesting was the Greenland sand-wort (_Arenaria_ (_Alsine_)
_Grænlandica_) which was blooming abundantly, with its clusters of
delicate white flowers, on the very summit of the mountain, and could
be found here and there by the side of the brook in the bottom of the
ravine.
Clambering by a steep and dangerous path up the right side of the
ravine, we reach almost at once the limit, beyond which the ordinary
flora of New England can extend no longer, and are in the presence of
a new group of plants comparable with those of Labrador and Greenland.
Here, on the plateau of the Lake of the Clouds, the traveller who has
ascended the giddy precipices overhanging Tuckerman's Ravine is glad
to pause, that he may contemplate the features of the new region which
he has reached. We have left the snow behind us, except a small patch
which lingers on the shady side of Mount Munro; for it is only in the
ravines into which it has drifted a hundred feet deep or more, that
it can withstand the summer heat until August. We stand on a dreary
waste of hard angular blocks of mica slate and gneiss that lie in rude
ridges, as if they had been roughly raked up by Titans, who might have
been trying to pile Monro upon Washington, but which seem to be merely
the remains of the original outcropping edges of the rocks broken up
by the frost, but not disturbed or rounded by water.[194] Behind us
is the deep trench-like ravine out of which we have climbed; on the
left hand a long row of secondary summits stretching out from Mount
Washington to the south-westward, and designated by the names of a
series of American statesmen. In front this range descends abruptly
in great wooded spurs or buttresses to the valley of the Amonoosook,
which shines in silvery spots through the trees far below. On our
right hand towers the peak of Mount Washington, still more than a
thousand feet above us, and covered with angular blocks, as if it
were a pile of fragments rather than a solid rock. These stones all
around and up to the summit of the mountain, are tinted pale green
by the map lichen (_Lecidea geographica_), which tinges in the same
way the alpine summits of European mountains. Between the blocks
and on their sheltered sides nestle the alpine flowering plants, of
which twenty species or more may be collected on this shoulder of the
mountain, and some of which extend themselves to the very summit,
where _Alsine Grœnlandica_ and the little tufts of deep green leaves
of _Diapensia Lapponica_ with a few Carices seem to luxuriate. Animal
life accompanies these plants to the summit, near which I saw a family
of the snow bird, evidently summer residents here, instead of seeking
the far north for a breeding place, as is the habit of the species, and
a number of insects, conspicuous among which was a brown butterfly of
the genus _Hipparchia_. Shortly before sundown, when the thermometer at
the summit house was fast settling toward the freezing point, a number
of swallows were hawking for flies at a great height above the highest
peak. To what species they belonged I could not ascertain. Possibly
the cliff swallows find breeding places in the sides of the ravines,
and rise over the hill top to bask in the sunbeams, after the mountain
has thrown its shadows over their homes.
[194] Hitchcock has since found travelled blocks on the summit, bearing
evidence to its submergence under the waves of the glacial sea, and
to the grinding of ice floes upon it. Such a fact helps to account
for the broken character of the summit, and also implies that unequal
subsidence of the land elsewhere referred to, since we know of no
agency which could carry boulders so high as the present mountain top.
To return to the Alpine flora which is peculiar to the peaks of these
mountains--are the species comprising it autochthones originating on
these hill tops, and confined to them, or are they plants occurring
elsewhere, and if so, where? and how and when did they migrate to their
present abodes? These are questions which must occur to every one
interested in geology, botany, or physical geography.
Not one of the Alpine plants of Mount Washington is peculiar to
the place. Nearly all of them are distinct from the plants of the
neighbouring lowlands, but they occur on other hills of New England
and New York, and on the distant coasts of Labrador and Greenland, and
some of them are distributed over the Arctic regions of Europe, Asia
and America. In short, they are stragglers from that Arctic flora which
encompasses the north polar region, and extends in promontories and
islands along the high cold mountain summits far to the southward.
Some of the humble flowerless plants of these hills are of nearly
world-wide distribution. I have already noticed the pale green map
lichen which tints the rocks of the Pyrenees, the Alps, and the
Scottish Highlands; and the curious ring lichen (_Parmelia centrifuga_)
paints its conspicuous rings and arcs of circles alike on Mount
Washington and the Scottish hills. A little club moss (_Lycopodium
selago_) is not only widely distributed over the northern hemisphere,
but Hooker has recognised it in the Antarctic regions. Not long ago we
unrolled in Montreal an Egyptian mummy, preserved in the oldest style
of embalming, and found that, to preserve the odour of the spices,
quantities of a lichen (_Evernia furfuracea_) had been wrapped around
the body, and have no doubt been imported into Egypt from Lebanon, or
the hills of Macedonia, for such uses. Yet the specimens from this old
mummy were at once recognised by Professor Tuckerman as identical with
this species as it occurs on the White Hills and on Katahdin, in Maine.
These facts are, however, easily explicable in comparison with those
that relate to the flowering plants.
The spores of lichens and mosses float lighter than the lightest down
in the air, and may be wafted over land and sea, and dropped everywhere
to grow where conditions may be favourable. We can form an idea of this
from the fact that the volcanic dust, consisting of shreds of pumice,
etc., thrown up by the eruption of Krakatoa, in 1883, was wafted, in a
day or two, round the globe, and remained suspended for months in the
atmosphere. The spores of many cryptogamous plants are even lighter
than volcanic dust. Had the Egyptian embalmer used some of the first
created specimens of _Evernia furfuracea_, it might easily, within the
three thousand years or so since his work was done, have floated round
the world and established itself on the White Hills. But, as we shall
see, neither the time nor means would suffice for the flowering plants.
The only available present agency for the transmission of these would
be in the crops or the plumage of the migratory birds; and when we
consider how few of these, on their migrations from the north, could
ever alight on these hills, and the rarity of their carrying seeds in
a state fit to vegetate, and further, that few of these plants produce
fruits edible by birds, or seeds likely to attach themselves to their
feathers, the chances become infinitely small of their transmission in
this way. The most profitable course of investigation in this and most
other cases of apparently unaccountable geographical distribution, is
to inquire as to the past geological conditions of the region, and how
these may have affected the migrations of plants.
The earlier geological history of these mountains far antedates our
existing vegetation. It belongs, in the first instance, to the Archæan
and early Palæozoic period, in which the materials of these mountains
were accumulating, as beds of clay and gravel, in the sea bottom. These
were buried under great depths of newer deposits, and were folded
and crumpled by lateral pressure, baked and metamorphosed into their
present crystalline condition.[195] Again heaved above the sea level,
they were hewn by the action of the waves to some degree into their
present forms, and constituted part of the nucleus of the American
continent in the later Tertiary period, when they were probably higher
than now. They were again, with all the surrounding land, depressed
under the sea in the Pleistocene period, and in the Post-glacial or
modern, slowly upheaved again to their present height. These last
changes are those that concern their present flora, and their relations
to it are well stated by Sir C. Lyell in the following passages from
his interesting account of his ascent of Mount Washington in 1840.
[195] While the mass of the White Mountains is probably older than the
Silurian, there are beds of mica schist which contain corals of the
genus Halysites, and stems of large crinoids.
"If we attempt to speculate on the manner in which the peculiar
species of plants now established on the highest summits of the White
Mountains were enabled to reach those isolated spots, while none of
them are met with in the lower lands around, or for a great distance
to the north, we shall find ourselves trying to solve a philosophical
problem which requires the aid, not of botany alone, but of geology,
or a knowledge of the geographical changes which immediately preceded
the present state of the earth's surface. We have to explain how
an Arctic flora, consisting of plants specifically identical with
those which inhabit lands bordering the sea in the extreme north of
America, Europe and Asia, could get to the top of Mount Washington.
Now geology teaches us that the species living at present on the earth
are older than many parts of our existing continents; that is to say,
they were created before a large portion of the existing mountains,
valleys, plains, lakes, rivers, and seas were formed. That such must
be the case in regard to Sicily I announced my conviction in 1833,
after first returning from that country; and a similar conclusion
is no less obvious to any naturalist who has studied the structure
of North America, and observed the wide area occupied by the modern
or glacial deposits, in which marine shells of living but northern
species are entombed. It is clear that a great portion of Canada, and
the country surrounding the great lakes, was submerged beneath the
ocean when recent species of molluska flourished, of which the fossil
remains occur about 500 feet above the level of the sea at Montreal.
Lake Champlain was a gulf or strait of the sea at that period, large
areas in Maine were under water, and the White Mountains must then
have constituted an island or group of islands. Yet, as this period
is so modern in the earth's history as to belong to the epoch of the
existing marine fauna, it is fair to infer that the Arctic flora, now
contemporary with this, was then also established on the globe.
"A careful study of the present distribution of animals and plants
over the globe has led nearly all the best naturalists to the opinion
that each species had its origin in a single birthplace, and spread
gradually from its original centre to all accessible spots fit for its
habitation, by means of the powers of migration given to it from the
first. If we adopt this view, or the doctrine of specific centres,
there is no difficulty in comprehending how the _Cryptogamous_ plants
of Siberia, Lapland, Greenland and Labrador scaled the heights of Mount
Washington, because the sporules of the fungi, lichens and mosses may
be wafted through the air for indefinite distances, like smoke; and,
in fact, heavier particles are actually known to have been carried
for thousands of miles by the wind. But the cause of the occurrence
of Arctic plants of the _Phænogamous_ class on the top of the New
Hampshire Mountains, specifically identical with those of remote polar
regions, is by no means so obvious. They could not in the present
condition of the earth effect a passage over the intervening lowlands,
because the extreme heat of summer and cold of winter would be fatal to
them. We must suppose, therefore, that originally they extended their
range in the same way as the plants now inhabiting Arctic and Antarctic
lands disseminate themselves. The innumerable islands in the polar seas
are tenanted by the same species of plants, some of which are conveyed
as seeds by animals over the ice, when the sea is frozen in winter,
or by birds; while a still larger number are transported by floating
icebergs and field ice, on which soil containing the seeds of plants
may be carried in a single year for hundreds of miles. A great body of
geological evidence has now been brought together to show that this
machinery for scattering plants, as well as for carrying erratic blocks
southward, and polishing and grooving the floor of the ancient ocean,
extended in the western hemisphere to lower latitudes than that of the
White Mountains. When these last still constituted islands, in a sea
chilled by the melting of floating ice, we may assume that they were
covered entirely by a flora like that now confined to the uppermost or
treeless region of the mountains, except in such portions of the period
as were sufficiently cold to clothe their summits permanently in snow.
As the continent grew by the slow upheaval of the land, and the islands
gained in height, and the climate around these hills grew milder, the
Arctic plants would retreat to higher zones, and finally occupy an
elevated area, which probably had been, at first, or in the Glacial
period, always covered with perpetual snow. Meanwhile the newly formed
plains around the base of the mountain, to which northern species of
plants could not spread, would be occupied by others migrating from
the south, and perhaps by many trees, shrubs, and plants, then first
created, and remaining to this day peculiar to North America."
The time to which the above views of Sir. C. Lyell would refer the
migration of the White Mountain flora, is historically, very remote.
The changes of level which have submerged the American continent and
re-elevated its land have occupied long periods. Whether, with Lyell,
we measure these periods by the recession of the Falls of Niagara,
or by the growth of the alluvial plain of the Mississippi; or, with
Agassiz, by the extension of the peninsula of Florida, or endeavour to
estimate the time required for the abrasion and deposition of the great
mass of clay that fills the valley of the St. Lawrence, and allowing
for the reductions of the antiquity of the Glacial period arising from
recent observations and calculations, we cannot suppose that less than
8,000 or 10,000 years have elapsed since the Alpine plants of the White
Mountains were cut off from all connection with their Arctic relatives.
Their reign upon the mountain tops not only antedates all human
dynasties, but probably reaches beyond the creation of man himself, and
many of his contemporaries.
Positive evidence of the existence of some of these plants during a
large portion of this lapse of time has actually been preserved in
the Pleistocene deposits of Canada. At Green's Creek, on the Ottawa,
in nodules in the clay containing marine shells, and coeval with the
Leda clay of Montreal, there are numerous remains of plants that have
been embedded in this clay at a time when the Ottawa valley was a bay
or estuary, and when the Adirondack Mountains of New York and the
mountains of New England were two rocky islands, separated from each
other and from the mainland on the north by wide arms of the sea. The
plants found in these nodules all appear to be of modern species.
Several of these plants are found on the White Mountains, and they are
all northern or boreal, but scarcely Arctic, belonging as they do to
the southern margin of the Arctic land species. I have no doubt that
further examination of these deposits will lead to the discovery of
additional examples. This fact, proving as it does the existence of
these species at the period in which the theory of Lyell and Forbes
requires them to have migrated, is in itself strong corroborative
evidence. We can say that some of these species were waiting on the
shores of the north, ready to be drifted to the insular spots to the
south-west, and that their seeds were actually being washed out to sea
by the streams which emptied themselves into the then estuary of the
Ottawa.
Another aspect of the inquiry is that which relates to the reduction of
temperature, which might be consequent on the great depression of the
land which we know to have existed at the close of the Tertiary period,
a fact on which I have insisted in former papers on the Pleistocene
deposits of Canada.[196] A very clever writer on the subject of
geographical distribution[197] has pictured the case of a subsiding
continent, with the fauna and flora of its lowlands becoming gradually
concentrated on the spots which had previously been Alpine summits, but
now reduced to low and temperate islands. But he has left out of view
the fact, that if land still existed in mass in the Arctic regions, and
if the subsidence was that of land in temperate regions, and if the
remaining islands were encompassed with cold and ice-laden currents,
then, on the principles long ago so well stated by Sir C. Lyell, these
islands might have a mean temperature far below that of the former
plains, and might, in consequence, be suitable only to such an Alpine
flora as that which they had previously borne.
[196] _Canadian Naturalist_, vol. iv.
[197] Wollaston.
Now this is precisely what seems to have occurred in the Pleistocene
period. The Arctic land remained in great mass, detaching into the sea
annual crops of icebergs and fields of coast ice, which have strewed
all the northern hemisphere with boulders: the temperate regions were
submerged, except a few insular spots. These are the very conditions
required for a low mean temperature, both in the sea and on the land,
and these geographical conditions correspond precisely with the facts
as indicated by the fossil animals and plants of the period. We must
bear in mind, however, that under certain contingencies the high
mountain summits might have been clad in snow and ice, like Greenland,
and the Alpine plants might have been able to live only on their
margins.
Further, it would be easy to show that the Alpine plants of Mount
Washington would thrive under such conditions as those supposed, at
the sea level; a low and equable temperature, with a moist atmosphere,
being that which they most desire, and their greatest enemy being the
dry parching heat of the plains of the temperate regions. Those of
them, such as _Potentilla tridentata_ and _Alsine Grœnlandica_, which
occur in low ground within the limits of the United States, are found
under shaded woods, in damp ravines, or on the moist sea-coast; and
as we follow the coasts northward, we find these plants, on these and
on neighbouring islands, in lower latitudes than those in which they
occur inland. This is well seen in Northern New Brunswick and in the
south shore of the St. Lawrence, where several northern species occur
in shady and moist localities. I have, for example, collected _Cornus
Suecica_ and the Alpine birch in such places. When the summer mists
roll around the summit of Mount Washington, it is in every respect the
precise counterpart of an islet anywhere on the coast of America, from
Cape Breton to the Arctic seas, and when winter wraps everything in
a mantle of snow, all these lands are in like manner under the same
conditions. So, in the Pleistocene period, though the islets of the
White Mountains may have experienced a less degree of winter cold, they
must have had very nearly the same summer temperature as now; and as
this is the season of growth for our Alpine and Arctic plants, it is
its character that determines the suitableness of the locality to them.
Those stupendous vicissitudes of land and water which have changed the
aspect of continents, and swept into destruction races of gigantic
quadrupeds, have dealt gently with these Alpine plants, which long
ages ago looked out upon a waste of ice-laden waters that had engulfed
the Pliocene land with all its inhabitants, as securely as they now
look down upon the pleasant valleys of New England. It is curious, too,
that the humbler tenants of the sea have shared a similar exemption. In
the clay banks of the Saco, on the shores of Lake Champlain, and mixed
with the remains of these very plants in the valley of the Ottawa, are
shells that now live in the Gulf of St. Lawrence and on the coast of
Maine, intermixed with other species that are now found only in a few
bays of the Arctic seas. Just as in the Post-pliocene clays of the
Ottawa, the remains of northern plants are found in the same nodule
with those of _Leda glacialis_, so now similar associations maybe
taking place on the coasts at the mouth of the Great Fish River. Truly,
in nature as in grace, God hath chosen the weak things of the world to
confound those that are mighty, and has left in the earth's geological
history, monuments of His respect and regard for the humblest of His
works.
It is interesting to notice here that Greenland, at the present time,
presents conditions as to vegetation which may, in some respects,
correspond to those of the White Mountains in Pleistocene times. Its
flora, though altogether Arctic, contains 386 species, none of which
are peculiar to it, but many of them range quite round the Polar
circle. Of those that are not so generally distributed, some, more
especially on the west coast, are common to Greenland and Arctic
America. Others, and a larger number, more especially on the east
coast, are common to Greenland, Iceland and Norway, between which and
Greenland there may have been a closer land connection than now, in
Pliocene and Post-glacial times.
We look in vain among the Alpine plants, so long isolated in these
mountains, for any evidence of decided change in specific characters.
The Alpine plants, for ages separated from their Arctic brethren,
are true to their kinds, and show little tendency to vary, and none
to adapt themselves to new forms in the sunny plains below. This is
especially noteworthy on Mount Washington and the neighbouring peaks,
because the soil of these is the same with that of the valleys.
Several of the plants peculiar to these hills, as the black crowberry
(_Empetrum nigrum_), for instance, even when other conditions are
favourable, shun rich calcareous soils, and affect those of granitic
origin. In many cases the difference in soil is a sufficient reason for
the non-occurrence of such plants, except on certain hills. At Murray
Bay, and on the shores of Lake Superior, the plant above named occurs
only on the Laurentian gneiss. In Nova Scotia, its relative, _Corema
Conradi_, is confined to the granite barrens of the south coast. Many
such plants skirt the whole Laurentian range from Labrador to Lake
Superior, but refuse to extend themselves over the calcareous plains
of Canada. But in the White Hills the soil of the river alluvium is
the same micaceous sand that fills the crevices of the rocks in the
mountains, and hence there is no obstruction, in so far as soil is
concerned, to the diffusion of plants upward and downward in the hills.
In like manner there is every possible condition as to moisture and
dryness, sunshine and shade, in both localities. These circumstances
are of all others the most favourable to such variation as these plants
are capable of undergoing. The case is the same with that which Hugh
Miller so strongly puts in relation to the species of algæ that occur
at different distances below high water mark on the coast of Scotland,
each species there attaining a certain limit, and then, instead of
changing to suit the new conditions, giving place to another. So it is
on Mount Washington; and this, whether we regard the lowland plants
that climb to a certain height, and there stop, the plants that are
common to the base and summit, or the plants that are confined to the
latter.
I have already referred to the evident struggle of the spruces and
firs, and the plants associated with them, to ascend the mountain,
and the same remark applies to all the plants that one after another
cease to appear at various heights from the lower valleys. One by one
they become stunted and depauperated, and then cease, without any
semblance of an attempt to vary into new and hardier forms. And this
must have been proceeding, be it observed, from all those thousands
of years that have elapsed since the elevation of the mountains out
of the glacial seas. It is to be observed, also, that the new plants
that occur in ascending, often belong to different genera and families
from those left behind, not to closely allied species; and in the few
cases in which this last kind of change occurs, there is no graduation
into intermediate forms. For instance, _Solidago thyrsoidea_ and _S.
virga-aurea_[198] occur around the base of the mountain, and for some
distance up its sides. At the height of four to five thousand feet the
latter only remains, and this in a dwarfish condition. This corresponds
to its distribution elsewhere, for, according to Richardson, it occurs
in lat. 55° to 65° in Arctic America, and according to Hooker, it is
found in the Rocky Mountains, while it also occurs in the hills of
Scotland, and very abundantly in some parts of Norway. In the White
Mountains _S. thrysoidea_ prevails toward the base, _S. virga-aurea_
toward the summit; and at the top of Tuckerman's ravine I found the
former of these golden rods in blossom, within a few hundred feet of
the latter, each preserving its distinctive peculiarities. Much has
lately been said of the appearance of specific diversity that results
from the breaking up of the continuity of the geographical areas of
plants by geological changes; but here we probably have the converse
of this. The mountain species is no doubt a part of the older Arctic
flora, the other perhaps belong to a more modern flora, and they have
met on the sides of the White Hills.
[198] Macoun thinks that most of the specimens referred to this species
belong to the allied form, _S. Mulllinallata_, Ast, which is very
extensively distributed on the mountains of British America and in the
Arctic regions.
Some hardy species climb from the plains to heights of 5,000 feet
or more, with scarcely even the usual change of being depauperated,
and then suddenly disappear. This is very noteworthy in the case
of two woodland plants, the dwarf cornel or pigeon-berry (_Cornus
Canadensis_), and the twin-flower (_Linnæa borealis_). The former of
these is a plant most widely distributed over northern America, and
probably belongs to that newer flora which overspread the continent
after its re-elevation. In August this plant in the woods around
the base of Mount Washington is loaded with its red berries. At an
elevation of four to five thousand feet it may be found in bloom; above
this a few plants appear, destitute of flowers, dwarfish in aspect,
and nipped by cold, and then the species disappears. No doubt the
birds that feed on its little drupes have carried it up the mountain,
and have sown it a little farther up than the limit of its probable
reproductiveness. The beautiful little _Linnæa_ is a still more widely
distributed plant; for it occurs on the hills of northern Europe,
and is found across the whole breadth of the American continent from
Nova Scotia to the Columbia River. It is almost beyond question a
member of the old Arctic flora which colonized the islands of the
Pleistocene sea, and 'has descended from them on all sides as the land
became elevated. This plant also climbs Mount Washington to a height
of 5,000 feet, and presents precisely the same characters on the top
as at the bottom, only losing a little in the length of its stem.
Specimens bearing blossoms, and quite in the same stage of growth,
may be collected at the same time on the highest shoulders of Mount
Washington, and on the flats at Gorham. The _Linnæa_ in this is true to
its designation. For, as if it belonged to it to support the reputation
of the great systematist after whom it is named, it preserves its
specific characters with scarcely a tittle of change throughout all its
great range. One cannot see this hardy little survivor of the Glacial
period, so unchanging yet so gentle, so modest yet so adventurous,
so wide in its migrations yet so choice in the selection of the mossy
nooks which it adorns with its pendant bells, and renders fragrant with
its delicious perfume, without praying that we might, in these days
of petty distinctions and narrow views, be favoured with more such
minds as that of the great Swede, to combine the little details of the
knowledge of natural history into grand views of the unity of nature.
Another plant which, being less dependent on shade and shelter than the
_Linnæa_, mounts still higher, is the cowberry or foxberry (_Vaccinium
vitis-Idæa_). This, also, is both European and American, and is
probably a survivor of the Pleistocene period. It still occurs in at
least one locality in the low country of Massachusetts, and on the
coast of Maine. It is found along the granitic coast of Nova Scotia,
and extends thence northward to the Arctic circle, being found at Great
Bear Lake and at Unalaska. This, too, is a most unchanging species,
and the same statement may be made respecting the cloudberry (_Rubus
Chamæmorus_), the black crowberry (_Empetrum nigrum_), the Labrador
tea (_Ledum latifolium_), the three-toothed cinquefoil (_Potentilla
tridentata_), which grows on the coast of Nova Scotia, and is found in
the nodules of the Ottawa clay, the same in every detail as on Mount
Washington, the bog bilberry (_Vaccinium uliginosum_), and the dwarf
bilberry (_V. cæspitosum_). Several of these, too, it will be observed,
are berry-bearing plants, whose seeds must be deposited in all kinds of
localities by birds. Yet they never occur in the warm plains, nor do
they show much tendency to vary in the distant and somewhat dissimilar
places in which they occur. In the case of most of these species, the
most careful comparison of specimens from Mount Washington with those
from Labrador, shows no tittle of difference. When we consider the
vast length of time during which such species have existed, and the
multiplied vicissitudes through which they have passed, one is tempted
to believe that it is the tendency of the "struggle for existence" to
confirm and render permanent the characters of species rather than to
modify them.
Of the more specially Arctic plants which have held their ground
unchanged on Mount Washington, the following are some of the principal.
_Diapensia Lapponica_, in beautiful deep green tufts, ascends quite
to the summit. It occurs also in the Adirondack Mountains, on Mount
Katahdin, in Maine, and on the summit of Mount Albert, Gaspé (Macoun).
It is found in Labrador, and, according to Hooker, extends north to
Whale Island, in the Arctic seas; but it is not found west of the
Great Fish River. It occurs also on the mountains of Lapland, and
is described as the hardiest plant of that bleak region. _Arenaria_
(_Alsine_) _Grænlandica_, the Greenland sand-wort, adorns with its
clusters of white flowers every sandy crevice in the rocks of the very
summit of Mount Washington, and is trodden under foot like grass by
the hundreds of careless sightseers that haunt that peak in summer;
though I should add, that not a few of them carry off little tufts as
a memento of the mountains, along with the fragments of mica which
appear to form the ordinary keepsakes of unscientific visitors. It
is a most frail and delicate plant, seemingly altogether unsuited to
the dangerous pre-eminence which it seeks, yet it loves the bare,
unsheltered mountain peaks, and when it occurs in the more sheltered
ravines, has only its stems a little longer and more slender. It occurs
on the Adirondack Mountains and on Katahdin, where, if I may judge from
specimens kindly sent to me by Prof. Goodale, it attains to smaller
dimensions than on Mount Washington, on the Catskills, and at one place
on the sea coast of Maine. I have not seen it in Nova Scotia, but it
ranges north to Greenland.
Another of the truly Arctic plants is the alpine azalea (_Loiseleuria
procumbens_), a densely tufted mountain shrub, with hard glossy
leaves, that look as if constructed to brave extremest hardships. It
is found on the mountains of Norway, at the height of 3,550 feet on
the Scottish hills, according to Watson, and according to Fuchs, at
the height of 7,000 feet in the milder climate of the Venetian Alps.
In America it is found in Newfoundland, in Labrador, at 4,000 feet on
Mount Albert, Gaspé,[199] and in the barren grounds from lat. 65 to the
extreme Arctic islands. Gray does not mention its occurrence elsewhere
in the United States than the summits of the White Mountains. A member
of the same family of the heaths, the yew-leaved phyllodoce (_P.
taxifolia_), presents a still more singular distribution. It is found
on all the higher mountains of New England and New York, and occurs
also on the mountains of Scotland and Scandinavia, but its only known
station in northern America is, according to Hooker, in Labrador. As
many as nine or ten of the Alpine plants of the White Mountains belong
to the order of the Heaths (Ericaceæ). Another example from this
order is _Rhododendron Lapponicum_, a northern European species, as
its name indicates, and scattered over all the high mountains of New
England and New York, occurring also in Labrador, on the Arctic sea
coasts, and the northern part of the Rocky Mountains, and at 4,000 feet
on Mount Albert, Gaspé (Macoun).
[199] Macoun.
It would be tedious to refer in detail to more of these plants, but I
must notice two herbaceous species belonging to different families,
but resembling each other in size and habit the Alpine epilobium (_E.
alpinum_ or _alsinefolium_), and the Alpine speedwell (_Veronica
alpina_). Both are in the United States confined to the highest
mountain tops. Both occur as alpine northern plants in Europe, being
found on the Alps, on the Scottish Highlands, and in Scandinavia. Both
are found in Labrador and on the Rocky Mountains, and the Veronica
extends as far as Greenland. The Alpine epilobium is one of the few
White Mountain plants that have attained the bad eminence of being
regarded as doubtful species. Gray notes as the typical form, that with
obtuse and nearly entire leaves, and as a variety, that with acute and
slightly toothed leaves, which some other botanists seem to regard
as distinct specifically. Thus we find that this little plant has
been induced to assume a suspicious degree of variability; yet it is
strange that both species or varieties are found growing together, as
if the little peculiarities in the form of the leaves were matters of
indifference, and not induced by any dire necessities in the struggle
for life. Facts of this kind are curious, and not easily explained
under the supposition either of specific unity or diversity. For why
should this plant vary without necessity? and why should two species so
much alike be created for the same locality? Perhaps these two species
or varieties, wandering from far distant points of origin, have met
here fortuitously, while the lines of migration have been cut off by
geological changes; and yet the points of difference are too constant
to be removed, even after the reason for them has disappeared. If this
could be proved, it would afford a strong reason for believing the
existence of a real specific diversity in these plants.
I have said nothing of the grasses and sedges of these mountains; but
one of them deserves a special notice. It is the Alpine herd's grass
(_Phleum alpinum_), a humble relation of our common herd's grass. This
plant not only occurs on the White Mountains, in Arctic America, in
the Canadian Mountains, from the summit of Mount Albert, in Gaspé, to
the mountains of British Columbia, and on the hills of Scotland and
Scandinavia, but has been found on the Mexican Cordillera and at the
Straits of Magellan. The seeds of this grass may perhaps be specially
suited for transportation by water, as well as by land. It is observed
in Nova Scotia that when the wide flats of mud deposited by the tides
of the Bay of Fundy, are dyked in from the sea, they soon become
covered with grasses and carices, the seeds of which are supposed to be
washed down by streams and mingled with the marine silt; and fragments
of grasses abound in the Post-tertiary clays of the Ottawa.
It seems almost ridiculous thus to connect the persistence of the
form of a little plant with the subsidence and elevation of whole
continents, and the lapse of enormous periods of time. Yet the Power
which preserves unchanged from generation to generation the humblest
animal or plant, is the same with that which causes the permanence
of the great laws of physical nature, and the continued revolutions
of the earth and all its companion spheres. A little leaf, entombed
ages on ages ago in the Pleistocene clays of Canada, preserves in all
its minutest features the precise type of that of the same species as
it now lives, after all the prodigious geological changes that have
intervened. An Arctic and Alpine plant that has survived all these
changes maintains, in its now isolated and far removed stations, all
its specific characters unchanged. The flora of a mountain top is
precisely what it must have been when it was an island in the glacial
seas. These facts relate not to hard crystalline rocks that remain
unaltered from age to age, but to little delicate organisms that
have many thousands of times died and been renewed in the lapse of
time. They show us that what we call a species represents a decision
of the unchanging creative will, and that the group of qualities
which constitutes our idea of the species goes on from generation
to generation animating new organisms constructed out of different
particles of matter. The individual dies, but the species lives, and
will live until the Power that has decreed its creation shall have
decreed its extinction; or until, in the slow process of physical
change depending on another section of His laws, it shall have been
excluded from the possibility of existence anywhere on the surface of
the earth, unless we suppose with modern evolutionists that there is
a possibility of these plants so changing their characters that in the
lapse of ages they might appear to us to be distinct specific types.
The fact, however, that the Arctic species have migrated around the
whole Arctic circle, and have advanced southward and retreated to the
north, again and again, without changing their constitutions or forms,
augurs for them at least a remarkable fixity as well as continuity.
While the huge ribs of mother earth that project into mountain summits,
and the grand and majestic movement of the creative processes by which
they have been formed, speak to us of the majesty of Him to whom the
sea belongs, and whose hand formed the dry land, the continuance of
these little plants preaches the same lessons of humble faith in the
Divine promises and laws, which our Lord drew from the lilies of the
field.
It is suggestive, in connection with the antiquity and migrations of
these plants, to consider the differences in this respect of some
closely allied species of the same genera. Of the blueberries that
grow on the White Mountains, one species, _Vaccinium uliginosum_,
is found in Behring's Straits and very widely in Arctic and boreal
America,[200] also in northern Europe. _V. cæspitosum_ has a wide
northern range in America, but is not European. _V. Pennsylvanicum_ and
_V. Canadense_, from their geographical distribution, do not seem to
belong to the Arctic flora at all, but to be of more southern origin.
The two bearberries (_Arctostaphylos uva-ursi_ and _alpina_) occur
together on the White Hills, and on the Scottish and Scandinavian
mountains; but the former is a plant of much wider and more southern
distribution in America than the latter. Two of the dwarf willows of
the White Mountains (_Salix repens_ and _S. herbacea_) are European as
well as American, but _S. uva-ursi_ seems to be confined to America.
_Rubus triflorus_, the dwarf raspberry, and _R. chamæmorus_, the cloud
berry, climb about equally high on Mount Washington; but the former
is exclusively American, and ranges pretty far southward, while the
latter extends no farther south than the northern coast of Maine,
and is distributed all around the Arctic regions of the Old and New
Worlds. It is to be observed, however, that the former can thrive on
rich and calcareous soils, while the latter loves those that are barren
and granitic; but it is nevertheless probable that _R. triflorus_
belongs to a later and more local flora. Similar reasons would induce
the belief that the American dwarf cornel or pigeon-berry (_Cornus
Canadensis_), whose distribution is solely American, and not properly
Arctic, is of later origin than the _C. Suecica_,[201] which occurs in
northern America locally, and is extensively distributed in northern
Europe.
[200] Macoun, Catalogue of Canadian plants.
[201] I have found _C. Suecica_ growing along with _C. Canadensis_ in
shaded and northern exposures on the south side of the St. Lawrence,
near Caconna and Metis. Its seeds may have been brought over from
Labrador by migratory birds.
I can but glance at such points as these; but they raise great
questions which are to be worked out, not merely by the patient
collection of facts, but by a style of scientific thought very much
above those which, on the one hand, escape such problems by the
supposition of multiplied centres of creation, or on the other,
render their solution worthless by confounding races due to external
disturbing causes with species originally distinct. Difficulties of
various kinds are easily evaded by either of these extreme views; but
with the fact before him of specific diversity and its manifestly long
continuance, on the one hand, and the remarkable migrations of some
species on the other, the true naturalist must be content to work out
the problems presented to him with the data afforded by the actual
observation of nature, following carefully the threads of guidance
thus indicated, not rudely breaking them by too hasty generalizations.
But it is time to leave the scientific teachings of our little Alpine
friends, and to inquire if they can teach anything to the heart as well
as to the head.
The mountains themselves, heaving their huge sides to the heavens,
speak of forces in comparison with which all human power is nothing;
and we can scarcely look upon them in their majesty without a psalm
of praise rising up within us to Him who made the sea, and from whose
hands the dry land took its form. As we ascend them, and as our vision
ranges more and more widely over the tops of wooded hills, along the
courses of streams, over cultivated valleys, and to the shores of the
blue sea itself, our mental vision widens too. We think that the great
roots of these hills run beneath a whole continent, that their tops
look down on the wide St. Lawrence plain, on the beautiful valleys of
New England, and on the rice fields of the sunny south. We are reminded
of the brotherhood of man, which overleaps all artificial boundaries,
and should cause us to pray that throughout their whole extent these
hills may rise amidst a happy, a free, and a God-fearing people.
Our Alpine plants have still higher lessons to teach. They are fitting
emblems of that little flock, scattered everywhere, yet one in heart,
and in all lands having their true citizenship in heaven. They tell us
that it is the humble who are nearest God, and they ask why we should
doubt the guardian care of the Father who cares for them. They witness,
too, of the lowly and hidden ones who may inhabit the barren and lowly
spots of earth, yet are special subjects of God's love, as they should
be of ours. We may thus read in the Alpine plants truths that beget
deeper faith in God, and closer brotherhood with His people.
The history of these plants has also a strange significance. It might
have been written of them, "Though the dry land be removed out of its
place, and the mountains cast into the midst of the sea, yet the Lord
will not forsake the work of His hands"; for this has been literally
their history. In this they hold forth an omen of hope to the people of
God in that once happy land through which these hills extend, and who
now mourn the evil times on which they have fallen. The mountain plants
may teach them that though the floods of strife should rise even to the
tops of the hills, and leave but scattered islets to mark the place of
a united land, their rock is sure, and their prayers will prevail.[202]
The power that has waked the storm is after all their Father's hand.
For years a cry has risen high above these hills: the cry of the
bondman who has reaped the fields and received no hire. That cry is
sure to be heard in heaven, whatever other prayers may go unanswered.
An apostle tells us that it enters directly into the ears of the God
of Sabaoth, and is potent to call down the day of slaughter on the
proud ones of earth. The prayer of the slave has been answered; and the
tempest is abroad, sweeping away his oppressors and their abettors. Yet
God rules in all this, and those whom He has chosen will be spared,
even like the hardy plants of the hill tops, to look again on a renewed
and smiling land, from which many monsters and shapes of dread have for
ever passed away.
[202] This paper was originally written at the time when the American
Civil War was raging.
But last of all, the Alpine flowers have a lesson that should come
near to all of us individually. They tell us how well natural law is
observed, as compared with moral. Obeying with unchanging fidelity the
law of their creation, they have meekly borne the cold and storms of
thousands of winters, yet have thankfully expanded their bosoms to the
returning sun of every summer, and have not once forgot to open their
tiny buds, and bring forth flowers and fruit, doing thus their little
part to the glory of their Maker and ours. How would the moral wastes
of earth rejoice and be glad, did the sunshine of God's daily favours
evoke a similar response from every human heart!
References:--Paper on Destruction and Renewal of Forests in North
America, _Edinburgh Philosophical Journal_, 1847-8. Alpine and
Arctic Plants, _Canadian Naturalist_, 1862. "The Geological History
of Plants," International Scientific Series, 2nd edition, 1891.
"The Pleistocene Flora of Canada," Dawson and Penhallow, _Bulletin
American Geological Society_, 1890. Papers on Pleistocene Climate
of Canada, _Canadian Naturalist_, 1857 to 1890.
_EARLY MAN._
DEDICATED TO THE MEMORY OF THE LATE
SIR DANIEL WILSON, LL.D., F.R.S.E.,
a dear and valued Friend,
and one of the most eminent and judicious Students of
Pre-historic Man both in Europe and America.
Summary of the Story of Early Man--Classification of Tertiary
Time--Probabilities as to the Introduction of Man--The Anthropic Age As
Distinguished from the Pleistocene--Its Division into Palanthropic and
Neanthropic--Sketches of Palanthropic Man and His Immediate Successors
[Illustration: Four Pre-historic Skulls. (p. 472.)
Outer outline, _Cromagnon_; second, _Engis_; third, _Cannstadt_;
fourth, _Canadian Hochelagan_ on smaller scale.]