Considerations connected with the Glacier Theory, 39 



A sudden and pretty extensive cooling of the earth after 

 the existence of the elephants is therefore by no means proved 

 by the occurrence of frozen elephants in the Siberian ice, 

 and is just as little required for the explanation of this phe- 

 nomenon as for that of erratic blocks. We should, however, 

 meet with much greater obstacles were we to inquire into the 

 cause which could have produced such a refrigeration. From 

 the theory of a gradual cooling of the earth from a red-hot 

 condition to its present temperature, with which the hypothe- 

 sis coincides in other respects, we can only, apart from local 

 modifications, deduce a constant decrease of temperature, and 

 there is also no other astronomical or physical cause by which 

 an interrupted and intermitting diminution can be explained. 

 Without our being able to assign such a cause, the hypothesis 

 is not in any one point sufficient. It requires not only that 

 the temperature of the earth should have fallen, but also that 

 it should afterwards have been elevated ; and not only is it 

 necessary that this inexplicable occurrence should have taken 

 place at the end of the tertiary period, but also that, after 

 each of the five geological periods usually assumed at present, 

 such a great sudden diminution of temperature should have 

 destroyed all life, and that then the heat should have again 

 increased, and awakened new beings, in order to continue at 

 an equal height during the next period. In the work of Agas- 

 siz, we find only two attempts to establish this incorrect and 

 unnecessary theory. On one occasion, he remarks generally 

 (p. 306), " Nothing favom-s the idea that this diminution of 

 temperature was gradual ; on the contrary, whoever is accus- 

 tomed to regard nature in a physiological point of view, will 

 rather be inclined to assume that the temperature of the earth 

 was lowered by successive steps, and was again somewhat ele- 

 vated," &c. But the whole refrigeration theory, the whole 

 foundation of our present geology, which the ice-period hypo- 

 thesis itself recognises, is in favour of the gradual cooling ; 

 from it no other mode of cooling can be deduced, and the kind 

 of argument used by our author on another occasion, " no- 

 thing favours the idea," may with truth be directed against 

 his own supposition. At another place, p. 295, he says that 

 it was the elevation of the Alps out of the immeasurable 



