THE COBALT SERIES; ITS CHARACTER AND ORIGIN 131 
pointed out the resemblance of a greywacke conglomerate, occurring 
in the vicinity of Ramsay Lake, to bowlder clay; and in the same 
year, W. G. Miller mentioned the possibility of a glacial origin 
for the conglomerate of the Cobalt series, but also suggested desert 
conditions of deposition in the following quotation. ‘‘The writer 
is not able to offer a satisfactory explanation for the character of 
the sediments found in some of these strata. .... To account 
’ for the undecomposed and angular character of much of the frag- 
mental material, the writer is inclined to the belief that desert 
conditions prevailed in this region at the time some of the middle 
Huronian rocks, at least, were formed.’’* R. W. Brock in his report 
on the Larder Lake District published in 1907,? noted some charac- 
teristics of the rocks favorable to the glacial hypothesis but con- 
cluded that there were still difficulties in the way of its acceptance. 
He also observed that many of the included fragments had the 
form of bowlders worn by river sands. 
APPLICATION OF CRITERIA 
Although the various suggestions in the above quotations all 
imply a continental origin, none of these writers have pointed out 
the many characteristics of the series which point to terrestrial 
conditions of deposition. The great heterogeneity and general 
absence of complete sorting throughout the greater part of the 
series, the presence of ripple marks, current marks, cross-bedding, 
and interformational unconformities, the presence of an ancient 
soil at the base of the conglomerate in places, the angularity or 
subangularity of the fragmental material comprising the series, 
and the great thickness and enormous extent of the conglomerate 
are features distinctly characteristic of land sediments. It shall 
therefore be assumed without further discussion that the Cobalt 
series is of terrestrial origin, the term terrestrial implying depo- 
sition on the land in contrast with deposition in the sea or on the 
seashore. 
Continental clastic sediments may be formed by volcanic 
action or by weathering, creepage, lakes, rivers, winds, or glaciers, 
* Ann. Rep. Bur. of Mines, Ont. (1905), Pt. 2, p. 41. 
2 [bid., XVI (1907), 212. 
