538 S. V. Woo(l,jun. — American and British Stirface-Geology. 
As a preliminary, liowever, it may be well, for clearness sake, to 
recapitulate in tkeir descending order, from the newest to tbe oldest, 
the deposits of the St. Lawi-ence basin, with such alterations in 
their relative ages as I bave suggested, viz. : 
The later part of the Lake Terraces (beds No. 4), and the Eskers and Kames of 
the Canadian Highlands. 
The earlier part of the Lake Terraces (beds No. 4), and the Marine Clays. 
The Yellow Clays with Gravel and Boulders (beds No. 3a), and possibly a part 
of the Marine Clays. 
The Forest surface resting on the Erie Clay (bed No. 2). 
The Erie Clay (bed No. 1) which commenced with the formation of Eskers and 
Kames on the Ohio water-parting (beds No. 34). 
Approacliing then the examination in detail of tbe conditions 
under which we may seek to find grounds of synchronisra between 
tbe American and Englisk series, we have first the oldest members 
in tbe series of each country to examine ; and therefore, but witliout 
suggesting any synchronism between tbem by so doing, I place 
tbem side by side, viz. : 
English. 
St. Lawrence Basin. 
The Lower Glaeial Series. 
This series begins with a littoral and estuarine deposit 
of pebbly sands (the Bure Valley beds of myself, and 
Westleton Shingle of Prestwieh), containing a molluscan 
fauna ditfering but little (chiefly in the introduction of 
Tellina Balthica) from the later (Chillesford) beds of the 
Crag. These sands are fossiliferous in places, and cou- 
tain Mya truneata with valves United and siphonal ex- 
tremities vertical just as they lived ; and they pass up by 
interbedding into the Cromer Till, which is a deposit 
of deeper water, though also estuarine, and whose for- 
mation took place while the sands continued still in 
progress of accumulation in South Norfolk and North - 
East Suffolk. Up to this time, though the ice ripped off 
long sheets of Chalk, which are interstratified in the 
Cromer Till, it appears to me that the glacier-ice had 
not, in England at least, become confluent, i.e. formed 
into a continuous sheet. The series ends with the Con- 
torted Drift, a marine deposit of reddish-brown mud and 
silt, into which the Cromer Till passes up. This Drift 
was accumulated under a depth of water sufficient to float 
large bergs ; for these in grounding have buried huge 
masses of remanie Chalk in the mud and silt, contorting 
it in the process, though what that depth may have been 
is very difiicult to estimate. The glaciers had evidently 
much increased at this time, so as to form these bergs, 
but whether even then they were confluent over England 
is not apparent, as the glacier from which the bergs 
bearing the imbedded masses broke off must have been 
for great part of its course confined to the Chalk country, 
because these masses are formed almost entirely of reeon- 
structed Chalk. 
The Eskers and Kames 
of the Ohio water-part- 
ing, heing the washed- 
out moraine of the first 
ice-sheet, due to its 
dissolution subaerially, 
when at its southeru- 
most extension it termi- 
nated on that water- 
parting ; and the water 
dissolving from it flowed 
into the Valley of the 
Mississippi. The Erie 
clay (No. 1), being the 
unwashed moraine of 
this ice-sheet extruded 
at its margin, and left 
behind as it receded 
beneath the waters of 
the lake, which began 
to form so soon as the 
sheet shrunk back with- 
in the St. Lawrence 
basin. 
Of these accumulations of tbe period of first glacier development 
in eitber country, tkose of England clearly accompanied its incep- 
tion and increase, but tbose of America seem to bave accompanied 
