THE COBALT SERIES; ITS CHARACTER AND ORIGIN 139 
origin. In both of these deposits, bowlders have been found which 
have been attributed to floating ice.2 The Cobalt series differs from 
the Pleistocene deposits of northern Ontario and Quebec in the 
greater thickness of arkose and quartzite which it contains and in 
the presence of an upper conglomerate? overlying the finer grained 
members of the series. These conditions, however, would simply 
imply that the lake which covered the region subsequent to the 
deposition of the basal conglomerate was of longer duration than 
that of the Pleistocene, and that following the lacustrine epoch a 
second continental ice sheet advanced over the region from which 
an upper conglomerate was laid down. If it be assumed, therefore, 
that the conglomerates of the Cobalt series are of glacial origin, 
then there are at least two till sheets present, and the stratified 
greywacke, argillite, quartzite, and arkose constitute interglacial 
deposits. 
The essential similarity of the greywacke and argillite of the 
Cobalt series to the postglacial lacustrine clays of the region is 
shown in the following table of chemical analyses. Column Tis an 
analysis of the argillite and column II that of the stratified clay 
I Il Ill IV V 
SiO) ae eee 62.74 52.00 64.81 57-94 61.54 
NiOn as e oes 16.04 16.11 17.48 7scyy || obooe 
HesO mc x22. - SOV BEeSit a 
BO cos c : 1.59 § a-eo 1.64 § 5-83 * Once 
IMIS OF vey. ones: 3.05 4.10 3.14 ALAS Gig) eee ats 
CH OSs 5 are AO) 8.26 1.43 9.20 .84 
INGLO)N es huss < / 2.76 A 3.09 Ae 
ISAO Spoon J 6-07 Te 7ANN 6.2 1.95 2.84 
lel {O66 piloue 36 GQUOMPE MOB a, W  oteee ee NI) cleat 
1310) See Be |) Ge ee NS ce ieee |e er eee 
OM oh) ana sie OO ik. Acces TOM he Pease 
I. Ann. Rep. Bur. of Mines, Ont., XIV (1905), Pt. 2, p. 48. 
II. Ibid. (1905), p. 33- 
III. I recalculated to a total of 100 omitting water. 
IV. II recalculated to a total of 100 omitting water. 
V. Jour. Geol., XVIII (1910), 660. 
1 Ann. Rep. Bur. of Mines, Ont., XIV (1905), Pt. 2, p. 33; XVIII (1908), 282, 
284; Sum. Rep. Geol. Surv., Dept. of Mines, Can., 191. : 
2 Jour. Geol., XVI (1908), 153; Ann. Rep. Bur. of Mines, Ont., XX (1911), Pt. 1, 
p. 220. 
3 See table, pp. 124, 125. 
