3o8 The American Geologist. November, looi. 
it entered a lake standing twenty or thirty feet higher than Ontario. 
If this is correct, there had already heon a damming back of the inter- 
glacial waters to a higher level than has been reached yet in Post- 
glacial times. This damming could not have been by ice, for the 
climate was at least as mild as at present, since the tree trunks re- 
ferred to include wood of the red cedar, an elm, the pawpaw, and three 
species of oak ; and among the shellfish there arc two not reported 
from Canadian waters at the present day, though found in the Missis- 
sippi.. Quadrula (Unio) pyraniidata and Anodonta grandis. * * * 
SECTION AT T.WLOR's BRICKY.\RD. 
PERT. 
8. Yellow or brown sand with some reddish clay (no fossils) 3-60J/2 
7. Blue peaty clay with some gray sand ( Unios, wood, cari- 
bou horn) 4/^-57/^ 
6. Yellow to brown sand with thin laytTs of purplish clay 
(shells) 14-53 
5. Fine gray and yellow sand (Unios and other shells) 3-39 
4. Blue stratified clay and sand (Unios. with other shells, and 
lop^s of wood), above 23^ feet of boulder clay resting on 
Hudson River shale 2-36 
SECTION AT BENn QF DON. 
3. Brown clay with sandy layers (Unios Campeloma, etc) . . 5-34 
2. Blue clay with sandy layers (Unios, Anodons, wood) 6-29 
I. Coarse shingle with clay and peaty layers (shells and logs) 4-23 
River Don above lake Ontario 19-19 
From the combined section given above it will be seen that the 
warm climate beds of the Don, commencing 19 feet above lake Ontario, 
have a total thickness of 41 /^ feet. * * * T\\& lowest point at 
which the Unio clays and sands have been found is 41 feet below lake 
Ontario at the foot of Scarboro' Hights, giving a vertical range of 
more than 100 feet for the whole series of warm climate beds. * * * 
In all there are thirty-nine undoubted species of mollusks, and 
three more probably, included in the fauna. Of these eight or ten 
have- not been reported from lake Ontario, but occur farther south. 
[See Prof. Coleman's paper for lists of the species of the fauna and 
flora.] 
Professor Penhallow * * * states that "within this area no less- 
than thirty-eight species [of plants, mostly trees] have been recovered, 
and they point conclusively to the existence of climatic conditions dif- 
fering materially from those which now prevail, and of a character 
more nearly allied to those of the middle United States of today." 
"Only one species appears to have disappeared in Pleistocene time. 
Acer pleistocenicum, which was abundant in the region of the Don, 
bears no well defined resemblance to existing soecies." 
The plant remains consist chiefly of wood and leaves, the former 
usually much flattened from the pressure of the later ice-sheet, but 
otherwise often well preserved, the red cedar, for instance, showing 
