No. 1.] 



DAWSON — POST-PLIOCENE. 



41 



In the following table I have endeavoured to represent to the 

 eye the facts observed in the internal plain of the great Lakes, 

 and in the marginal area of the Atlantic slope, with the mode of 

 accounting for them on the rival theories of glacier ice and 

 floating ice. 



TABULAR VIEWS OP GLACIAL DEPOSITS AND THEORIES. 



It will be observed that the theoretical views diverge with 

 respect mainly to the Boulder-clay and the striation under the 

 Erie clay, and to the cause of the erosion of valleys in the Pliocene 

 land. I would merely remark, in addition to the considerations 

 already advanced, that the occurrence of drift-wood in the Erie 

 clay, and of sea shells in the Boulder-clay, are both most serious 

 objections to the glacier hypothesis, reserving for the sequel a 

 more full discussion of the rival theories. 



While the marginal marine area strictly corresponds to the 

 marginal areas of Europe, I have no distinct evidence that the 

 internal plains and table lands of the old continent correspond in 

 their formations to the internal lake area of America. 



An interesting fact with reference to the Erie clay, stated in 

 the Report of the Survey of Canada is, that these clays burn into 



