1880.] 435 [Stone. 
6. The Upper Marine Clays. These are for the most part 
browner or grayer than the lower clays, and few fossils have yet been 
found in them. They are in Maine commonly called clay-loam, and 
are often quite sandy in composition. They contain numerous stones 
and boulders, particularly the upper layers. In fact the surface is in 
some places so overwhelmed with boulders that‘ the formation closely 
resembles glacial till. Such formations are, however, quite local. 
On low levels the layers of the clay may be seen to come up to the 
sides of large boulders without distortion, showing that part of the 
clay was deposited after the boulder, also that the boulder dropped 
from above quietly. On the higher levels the distribution of these 
boulders overlying sedimentary clay, is different from that of glacial 
boulders, as they are massed on the northern slopes of hills, or in 
other places favorable for the stranding of ice floes. ‘The transport- 
ation of boulders by floes of shore ice from the ice foot may be seen 
almost every winter in the Penobscot and Passamaquoddy Bays. A 
smooth beach on the latter bay was not long since almost buried out 
of sight under the boulders brought there in a single season by 
stranded ice floes. The fossils found in our Champlain clays long 
ago showed that they were deposited in an icy sea, and this has been 
recently emphasized by the finding of a walrus skeleton at Portland, 
near the line between the upper and lower clays. ‘Transportation by 
floes and small bergs must have been more rapid in such a sea than it 
is at present, and may account for the erratics and what resembles 
till overlying the marine clays. In short, the writer as yet cannot 
find evidence of a general re-advance of the glacier after the depo- 
sition of the marine clays. The lower or fossiliferous clay is of 
Champlain age, and appears to correspond to the Leda clay of the 
Canadian naturalists. The upper or non-fossiliferous clay is in 
some respects the analogue of the Loess. It graduates by degrees 
into the under clay of the valley drift, or perhaps into the upper por- 
tion of that clay. Yet it is found over all, or nearly all that part of 
the State where are the fossiliferous marine clays, which shows that 
it cannot be wholly a fresh water or estuarine formation. Its hori- 
zontal transition into the clay of the valley drift, shows that a gen- 
eral re-advance of the glacier ought to cover the latter clay with till, 
but this has not yet been observed. 
7. Depositions by streams and the sea, during the recent, or 
terrace epoch. 
