1876.] The Former Climate of the Polar Regions. 359 
bounded on the south by an ocean extending from the Atlantic 
over the present deserts of Sahara and Central Asia to the 
Pacific. 
Between the Miocene and the present era are two important 
periods, the Pliocene and the Glacial, which to us are particu- . 
larly deserving of attention, inasmuch as that during them man, 
the lord of creation, seems first to have made his appearance. 
That during the latter of these periods vast masses of ice covered 
at least all the northern part of Europe is a well-known fact ; 
but concerning the nature of the transition from the glorious 
climate of the Miocene age to the Glacial period we possess no 
knowledge whatever founded on actual observation. Probably 
at some future time contributions towards the solution of this 
important question may be found amongst the mountain masses 
that occupy the peninsula between Ice-fjord and Bell Sound in 
Spitzbergen, or in some parts of the basalt region of Northwest- 
ern Greenland. In the interior of Ice-fjord and at several other 
places on the coast of Spitzbergen, one meets with indications 
either that the polar tracts were less completely covered with ice 
during the Glacial era than is usually supposed, or that, in con- 
formity with what has been observed in Switzerland, inter-glacial 
periods have also occurred in the polar regions. In some sand- 
s not very much raised above the level of the sea, one may i 
fact find the large shells of a mussel (Mytilus edulis) still living 
in the waters encircling the Scandinavian coast. It is now no 
longer found in the sea around Spitzbergen, having been prob- 
ably rooted out by the ice-masses constantly driven by the ocean 
currents along the coasts. 
rom what has been already stated, it appears that the animal 
and vegetable relics found in the polar regions imbedded in 
Strata deposited in widely separated geological eras uniformly 
testify that a warm climate has in former times prevailed over 
the whole globe. From paleontological science no support can 
be obtained for the assumption of a periodical alternation of 
warm and cold climates on the surface of the earth. 
A careful investigation of the structure of the different sedi- 
mentary strata leads to the same result. We are now very well 
acquainted with the origin and nature of the various strata, the 
substance of which has been supplied by the destructive opera- 
tion of glaciers on the surrounding and subjacent mountain 
Masses, and we can point out certain marks by which these 
strata may be distinguished from other non-glacial deposits. In 
