252 LAY SERMONS, ADDRESSES, AND REVIEWS. [xi. 



"Now, are geologists prepared to admit that, at some 

 time within the last 20,000 years, there has been all 

 over the earth so high a temperature as that ? I pre- 

 sume not ; no geologist — no modern geologist — would 

 for a moment admit the hypothesis that the present 

 state of underground heat is due to a heating of the 

 surface at so late a period as 20,000 years ago. If that 

 is not admitted, we are driven to a greater heat at some 

 time more than 20,000 years ago. A greater heating 

 all over the surface than 100° Fahrenheit would kill 

 nearly all existing plants and animals, I may safely say. 

 Are modern geologists prepared to say that all life was 

 killed off the earth 50,000, 100,000, or 200,000 years 

 ago ? For the uniformity theory, the further back the 

 time of high surface-temperature is put the better; 

 but the further back the time of heating, the hotter it 

 must have been. The best for those who draw most 

 largely on time is that which puts it furthest back ; 

 and that is the theory that the heating was enough 

 to melt the whole. But even if it was enough to 

 melt the whole, we must still admit some limit, such as 

 fifty million years, one hundred million years, or two 

 or three hundred million years ago. Beyond that we 

 cannot go." l 



It will be observed that the " limit ,J is once again 

 of the vaguest, ranging from 50,000,000 years to 

 300,000,000. And the reply is, once more, that, for 

 anything that can be proved to the contrary, one or 

 two hundred million yeara might serve the purpose, 

 even of a through-going Huttonian uniformitarian, 

 very well. 



But if, on the other hand, the 100,000,000 or 

 200,000,000 years appear to be insufficient for geo- 

 logical purposes, we must closely criticise the method 



1 Loc. tit., p. 24. 



