GEOLOGY. 205 



ered as proof of the existence of glaciers in the tropics, said that 

 such a depression of temperature on the earth's surface as would 

 fill the valley of the Amazon with ice would so profoundly affect 

 the life-history of the globe, that we could only accept it as an es- 

 tablished fact on the most unquestionable evidence ; that, if the 

 fact were proved, we must accept it with all its consequences, for 

 the true attitude of the man of science was that of a patient and 

 teachable child, sitting at the feet of Nature, and receiving her in- 

 structions without prejudice or passion ; but, until the evidence 

 of the former existence of glaciers in Brazil is proved beyond a 

 doubt, we must continue to give weight to the facts which seem 

 incompatible with it. These are : 



1. That nearly all forms of vegetable and animal life on the 

 globe would necessarily have been destroyed by a degree of cold 

 that would produce a glacier filling the valley of the Amazon ; 

 whereas nearly all the fossil plants and molluscs of the strata de- 

 posited immediately anterior to the glacial epoch are undis- 

 tinguishable from species now living in the same region. To 

 make this fact consistent with glaciers in the tropics, we must 

 suppose a new creation of undistinguishable species, in similar 

 relative numbers and distributed precisely as the pre-existent ones 

 were. 



2. Though unmistakable marks of glacial action are found on 

 all parts of the North American continent, down to the parallel 

 of 39 degrees, and on the mountains of California to the 35th par- 

 allel, they are not found further south, as they should have been 

 if the "ice period 11 froze the waters of the Amazon. 



VOLCANIC ERUPTION IN NICARAGUA. 



In the city of Leon, on the afternoon of the 14th November, 

 1867, the people were startled by the sudden and almost instanta- 

 neous breaking out of a number of volcanic rents on the western 

 or Pacific slope, near the base of the long extinct twin volcano of 

 Rosa, the middle one of the chain of volcanic cones which follow 

 each other in close succession from the northern extremity of the 

 lake of Managua to the Volcan el Viejo, the most prominent of 

 either, and a landmark for strangers desiring to enter the port 

 of Real e jo. , 



The first intimation of the eruption to the inhabitants of Leon, 

 only 10 miles distant in a direct line from the scene of the erup- 

 tion, was a low rumbling sound like distant thunder, shortly fol- 

 lowed by quick, sharp, and continuous reports, resembling the 

 roar of a not far distant battery of heavy artillery ; these reports, 

 and subsequent ones, were distinctly audible, on clear nights, at 

 the port of Corinto. 



On the night of the 14th, as soon as darkness followed the day, 

 there was revealed a sight which but few people in Central America 

 or elsewhere ever witnessed. Two large volcanic fires, with sev- 

 eral smaller ones scattered about on the plain, shed their lights on 

 the surrounding country, and even lit up with a warm glow the 

 towers of the cathedral in the plaza of Leon. 



