LOWER CLAYS. 55 



marine clays were being deposited; and if so, there must have been abun- 

 dant land vegetation. These teeth have since, however, been submitted by 

 Prof. L. A. Lee, of Bowdoin College, to Mr. J. A. Allen, author of "The 

 American Bisons, living and extinct."^ This expert, after comparing them 

 with a large number of bison teeth, pronounced them to be probably cow's 

 teeth, and of very modern date of deposition. In the present state of the 

 argument it will not do to insist on the ancient date of these teeth, and the 

 inference of a land vegetation in ]\Iaine at the time of the deposition of 

 marine clays can hardly be considered sustained. 



The Canadian geologists very generally employ the terms Leda Clay 

 and Saxicava Sand for the lower and upper marine beds, respectively. The 

 lower clays of Maine contain Leda and other fossils indicative of a muddy 

 bottom, and occasionally in a sandy beach I have found Saxicava and other 

 fossils characteristic of that sort of sea bottom. We have seen that the 

 high beaches are not found continuously, but only here and there in favor- 

 able situations. Over almost all the area of the marine beds of Maine the 

 lower clay (Leda Clay?) is not overlain by a fossiliferous sand. With 

 respect to Maine it is doubtful if the terms Leda Clay and Saxicava Sand 

 can be used in a stratigraphic sense as applying to deposits of different age 

 laid down one above the other; but the terms may well be used to indicate 

 the nature of the sediments which were deposited at different depths and 

 under different shore conditions. On such an irregular coast as that of 

 Maine the shore conditions would often vary rapidly. My investigations 

 do not as }'et enable me to give the chronology of the shallow-water sands 

 and the offshore clays. As it is not my purpose to refer to the marine 

 beds except as they are related to the glacial sediments, it is not necessary 

 here to give particular descriptions of the fossils. 



THE LOWER CLAYS: DELTAS DEPOSITED BY GLACIAL STREAMS. 



As already stated, the lower clays are often richly fossiliferous, but 

 the fossils are by no means evenly distributed. Thus, both at Brunswick 

 and Gardiner the lower clays contain great numbers of shells; Avhile at 

 East Bowdoinham, intermediate between those places, the fine blue clay 



' Memoirs of the Geological Survey of Kentucky, vol . 1, part 2, and memoirs of the Museum of 

 ComparatiVf Zoology at Harvard College, both Cambridge, 1876; also Ninth Annual Report of the 

 U. S. Gnol. and Geog. Surv. Terr., pp. 443-587, Washington, 1877. 



