302 REPORT OF THE AMERICAN COMMITTEE. 
because it underlies the drift sheet, the erosion has been greater 
and the oxidation is more thorough. The formation is the littoral 
part of a submarine deposit from the Roanoke to the Delaware, 
thus indicating a submergence of 100 feet on the Roanoke and 
450 feet on the Delaware. The upper part is brick-clay and 
loam ; the lower, gravel, sand, and boulders. The author finds 
evidence that the Columbia formation corresponds to the first 
glacial epoch ; that the two glacial epochs were separated by a 
very long non-glacial interval, which may have been ten times 
as long as either of the cold terms and five times as long as the 
post-glacial epoch. Pie differs from Chamberlin in his estimate 
of the place of the Loess, believing it to have been connected 
wdth the second till. 
Following the Quaternary marine deposits farther north, the 
reporter finds the first deposit containing boreal or Labrador shells 
at Gloucester, Mass., which is overlain by till. Very clear 
evidence of the relations of the fossiliferous beds to both tills is 
found at Portland, Me. Here clays and sands rise about 100 
feet above the sea and hold 121 species of organisms, all of 
living forms. They rest upon typical lower till, and are overlain 
by as much as 50 feet thickness of upper till. At the time the 
reporter described these facts the prevalent doctrine of the triple 
nature of the glacial period had not been established; but it 
seems clear that two seasons of ice-presence are indicated at this 
locality. Further east, in Maine and New Brunswick, the occur- 
rence of these fossiliferous clays is abundantly proved in the 
writings of various local geologists. No Plistocene with marine 
shells has been reported as yet from Nova Scotia. The boulder 
clay is underlain by a peaty bed. In Labrador, A. S. Packard, 
Jr., has described numerous molluscan remains in deposits up to 
the height of 600 feet. 
Sir William Dawson has thoroughly studied the Quaternary 
of the St. Lawrence valley, and has catalogued 205 species of 
animals and plants found fossil, all of them identifiable with 
living species. About 100 of the species are also named in the 
Portland list, showing the contemporaneity of the beds. Follow- 
ing the distinction indicated by C. B. Adams he calls the lower 
beds with pelagic species Leda clay, and the upper beds with 
littoral species, Saxicava sands. As he allows, both may have 
been in process of growth at the same time, so that these are not 
