526 Prof. NordensJcibld — Former Climate of Polar Regions. 



period liave thus happened, not only during this last period nearer 

 to our own time, but also many times before ; and there is reason 

 to suppose that they were also then followed by somewhat similar 

 results, — that is to say, that the cold and the warm eras have 

 many times alternated on the surface of the earth. In consequence 

 of this, it has become a matter of the utmost importance to science 

 to obtain by real observation accurate information as to the state of 

 temperature on the earth's surface during as many of the different 

 geological periods as possible. When in our days a scientific ques- 

 tion is seriously propounded, it is seldom long before it is answered; 

 and even in the instance before us we have of late years received 

 numerous contributions to geological climatology from lands the 

 geographical situation of which in the neighbourhood of the Pole 

 renders them best fitted to yield information of this kind. 



The geology of the polar tracts can in two different ways supply 

 us with information concerning the former climate, partly by a com- 

 parison of the fossil animals and plants there found with existing 

 forms that live under certain determinate climatic conditions, partly 

 by an accurate examination of the various strata of different geolo- 

 gical ages, with a view to ascertain whether these present any of the 

 indications which usually distinguish Glacial formations. 



We now possess fossil remains from the polar regions belonging 

 to almost all the periods into which the geologist has divided the 

 history of the earth. The Silurian fossils which McClintock brought 

 home from the American Polar Archipelago, and the German 

 naturalists from Novaja Semlja, as also some probably Devonian 

 remains of fish found by the Swedish Expeditions on the coasts of 

 Spitzbergen, are, however, too few in number, and belong to forms too 

 far removed from those now living, to furnish any sure information 

 relative to the climate in which they have lived. 



Immediately after the termination of the Devonian age, an ex- 

 tensive continent seems to have been formed in the polar basin north 

 of Europe, and we still find in Beeren Island and Spitzbergen vast 

 strata of slate, sandstone, and coal, belonging to that period, in 

 which are imbedded abundant remains of a luxuriant vegetation, 

 which, as well as several of the fossil plant-remains brought from 

 the polar regions by the Swedish Expeditions, have been examined 

 and described by Prof Heer of Zurich. We here certainly meet with 

 forms, vast Sigillaria, Calamites, and species of Lepidodendra, etc., 

 which have no exactly corresponding representatives in the now 

 existing plants. Colossal and luxuriant forms of vegetation, how- 

 ever, indicate a climate highly favourable to vegetable develop- 

 ment. A careful examination of the petrifactions taken from these 

 strata shows also so accurate an agreement with the fossil plants of 

 the same period found in many parts of the Continent of Central 

 Europe, that we are obliged to conclude that at that time no ap- 

 preciable difference of climate existed on the face of the earth, but 

 that a uniform climate extremely favourable for vegetation — but not 

 on that account necessarily tropical — prevailed from the Equator to 

 the Poles. 



