250 ANNUAL OF SCIENTIFIC DISCOVERY. 



locality, I have not the slightest doubt but that the terrace of limestone 

 overlays the grooved and polished rock in question. These instances, 

 although insufficient to decide the disputed question of the manner 

 in which the abrading forces acted, at least indicate that they existed, 

 and operated with the same effect, and doubtless under the same cir- 

 cumstances, during the eras of the calciferous sandstone and Trenton 

 limestone, as in the drift period. 



PARALLELISM OF THE DRIFT DEPOSITS OF EUROPE AND AMERICA. 



AT the Boston Natural History Society, April, the following re- 

 marks, on the above subject, were made by Mr. Desor : 



The main difficulty which we encounter, when we attempt to paral- 

 lelize the detrital deposits of Northern Europe and America with those 

 of Switzerland, where they have been first and most minutely investi- 

 gated, is the position of the bones of the mammoth and other animals. 

 In this country, and in the North of Europe they are limited to the 

 most recent formations, such as peat bogs, swamps and river alluvium. 

 In Switzerland and Italy, on the contrary, they occur in gravel deposits, 

 (diluvium,) which are said to have been deposited previous to the scat- 

 tering of the Alpine boulders over the plain of Switzerland and the 

 Jura, and previous, also, to the furrowing and polishing of the rocks. 

 It is plain, from these facts, that, in taking as a point of reference the 

 transportation of boulders and the polishing of the rocks, which are 

 similar in both countries, the mammoths of Switzerland and Italy must 

 have lived long before those of the North of Europe and America, being 

 moreover separated from them by the most important event of the 

 quaternary period, the transportation of boulders and furrowing of the 

 surface rocks. According to some geologists, it was an event of such 

 magnitude that it caused the destruction of all the living animals, 

 which were supposed to have been suddenly frozen to death ; and, in 

 support of this view, we are referred to the elephants which are found 

 frozen in the mud along the rivers of Siberia. Other geologists take a 

 different ground. They contend that, since the mammoths of the North 

 of Europe and America are identical with those of Italy and Switzer- 

 land, (Elephas primigenius,) they cannot but be of the same geological 

 age, and, rather than refer them to different periods, they prefer to op- 

 pose the assumption of a simultaneous transportation of boulders in 

 both countries ; thus assuming two glacial epochs instead of one. This 

 is especially the ground taken by M. D'Archiar. In reference to this 

 question, Mr. D. read the following extract from a letter from M. 

 Martins, Professor of Geology at the Sorbonne, at Paris : 



" I do not see why you consider it absolutely necessary that the 

 mammoths of Italy and those of the North of Europe and America 

 should have lived at the same epoch. I, for my part, do not feel com- 

 pelled to that conclusion. I go farther, and say that a priori the con- 

 trary opinion appears as the most warrantable. There, (in America,) 

 you have a vast continent, which is undergoing upheavals and subsi- 

 dences even during the actual period ; here, (in Switzerland,) you 

 have a country with high mountain chains, which, since the Pliocene 



