10 Traiisactiniix. — Misccllcoiroiix. 



alternately to or frora the north, introducing antarctic fauna into the 

 northern hemisphere dm-ing one cycle, and arctic at another into the 

 southern temperate zone. Their respective remains, intermingled at first 

 in the upper strata with those of tropical and suh-tropical forms, are now 

 being deposited layer upon layer over the beds which contain such different 

 ones below, and which will again in many places come to entomb the shells 

 and the bones of races similar in type to those which previously there 

 found a grave, when such a change in temperature as has occurred in most 

 regions over and over again takes place. 



The most enthusiastic glacialist could ask for no mightier engine than 

 the great antarctic stream bearing its vast islands of ice sixty miles and 

 more in length far towards the tropics in certain meridians. 



"What local influences are doing now in northern regions, students have 

 more ample opportunity of observing. Notably the condition of great part 

 of Greenland, where, in latitude 70°, ice islands of enormous dimensions 

 float off from a sea-chff of solid glacier ice 3,000 feet in height. The state 

 of things obtaining in that great land may be contrasted with that in the 

 equally misnamed country, Iceland, even that of its lower portions in 65° 

 N. with that of Lapland in 72°. The climate of the Crimea affords a use- 

 ful example when compared with that of Venice or Bordeaux. In conse- 

 quence of the radiation from the Thibetan steppes, we find cereals ripening 

 on the Siberian side of the Himalaya at a height above the sea equal to 

 that of the summit of Mont Blanc, whilst several thousand feet lower down 

 arctic cold prevails, and mighty glaciers do then- work above the burning 

 j)lains of Hindostau, growing under the soft breath of the rain-bearing 

 southerly winds. 



Again intense cold prevails over countries on the shores of that great 

 inlet of the North Pacific which, in not very remote times, teemed with 

 animal life of southern types. 



In that region where the Amoor river after flowing amidst uml)rageous 

 groves and vine-clad hiUs turns north and enters a frozen sea, a local 

 glacial period has possibly commenced, advancing with slow but unwaver- 

 ing steps, which might easily be accelerated by the subsidence of the shallow 

 sea-bottom which interrupts the flow of polar waters ; whilst in other places 

 owing to a deviation in the direction of local currents of warm and chilled 

 waters in seas of no great depth, sub-tropical forms are again multiplying 

 where but recently arctic ones usurped possession. 



The iron grasp of frost has loosened its hold over great part of "Western 

 America, and a temperate climate for ages has been gaining sway over the 

 arid regions where rivers flow in deep chasms or canons worn by them 

 through the plains under the Rocky Mountains. 



