386 THE NORTH POLAR BASIN. 



viz, 30^ to 35^ F., whilst iu siiinmer it prevents it from rising above 

 45° and 50^ F., a range of only 15^. In tlie valley of tlie Lena, in the 

 same latitude, the mean temperature of January is 55^^ to 50° F. below 

 zero, whilst that of July is 00° to 65° F. above zero, a range 115°. 



The close proximity of the Pacitic Ocean has a much less eftect on 

 the mean temperature at Bering Strait, which is in the same latitude 

 as the north of Iceland. The mean temperature for January is zero, 

 whilst that for July is 40° F. The mean temperature for January in 

 the same latitude in the valley of the Mackenzie is 25° below zero, 

 whilst that for July is 55° F. In this case the contrast of the ranges 

 is 40 and 80, which compared with 15 and 115 is small, but the geo 

 graphical conditions are not the same. Bering Sea is so protected by 

 the Aleutian chain of islands that very little of the warm current 

 from Japan reaches the straits. It is deflected southward, so the 

 Aleutian Islands form a better basis for comparison. Their mean tem- 

 perature for January is 35° F., whilst that for July is 50° F., precisely 

 the same difference as that to be found in Iceland. 



The influence of geographical causes upon climate being at present 

 so great, it is easy to imagine that changes in the distribution of land 

 and water may have had an equally important influence upon the cli 

 mate of the Polar Basin during the recent cold age, which geologists 

 call the Pleistocene i)eiiod. It is impossible for the traveler to over, 

 look the evidences of this so-called Glacial period in the Polar Basin; 

 and whether we seek an explanation of the geographical i)henomena 

 from the astronomer or the geologist, or both, it is impossible to ignore 

 the geographical interest of the subject. 



ARCTIC GEOLOGY. 



No sciences can be more intimately connected than geography and 

 geology. A knowledge of geography is absolutely essental to the geol- 

 ogist. To discriminate between one kind of rock and another is a 

 comparatively small part of the work of the geologist. To ascertain 

 the geographical distribution of the various rocks is a study of ])ro- 

 fouud interest. If the geologist owes much to the geographer, the lat- 

 ter is also largely indebted to the labors of the former. The geology of 

 a mountain range or an extended i^lain is as important to the physical 

 geographer as the knowledge of anatomy is to the figure painter. 



The geology of the Polar Basin is not very accurately known, and 

 the subject is one too vast to be more than mentioned on an occasion 

 like the present; but the evidences of a comparatively recent ice age in 

 eastern America and western Europe are too important to be passed by 

 without a word. 



In the sub-arctic regions of the world there is much evidence to 

 show that the climate has in comparatively recent times been Arctic. 

 The present glaciers of Central Eurojie were once much greater than 



