132 MORLEY E. WILSON 
the degree of importance and relationship of the latter agencies to 
one another depending, in part, on climate, and in part, on the 
topography of the land.* 
In the following discussion I shall apply some of the criteria 
which characterize sediments originating in these various ways to 
the different members of the Cobalt series, and in that way attempt 
to reach some conclusions as to the climate and conditions of 
deposition prevailing during this Huronian period. 
1. Pyroclastic origin.—Owing to the misunderstanding of the 
relationship of the Huronian of the Timiskaming region to the 
volcanic rocks of the older complex, the conglomerate of the Cobalt 
series was at one time thought to be of pyroclastic origin but it is 
now known that it is almost, if not entirely,? composed of material 
derived from the underlying floor. This mode of origin need not 
therefore be considered. 
2. Weathering and creepage.—Since weathering and creepage 
are closely related processes operating together, for the purpose of 
this discussion they may be considered as one. 
The indefinite contacts which occur at the base of the Cobalt 
series, in places, indicate that at the time the deposition of the 
series was Initiated, the surface of the ancient complex was covered 
by a considerable thickness of soil and that this has been preserved 
so that the basal beds of the conglomerate at these points represent 
a fossil regolith, developed zm situ by weathering. 
This ancient soil consisted of disaggregated, undecomposed 
rock fragments, a feature from which some inference may be drawn 
as to the climate prevailing at the time it was formed. The domina- 
tion of disintegration over chemical decomposition, on the earth’s 
surface today, is characteristic of regions? of youthful topography, 
is also characteristic of arid climates? and to a lesser extent of cold 
tJ. Barrell, Jour. Geol., XVI (1908), 159; A. Penck, Amer. Jour. Sci., XTX 
(1905), 166. 
2 Ann. Rep. Bur. of Mines (1905), Pt. 2, p. 47. 
3B. Willis, Jour. Geol., I (1893), 477. 
4K. Pumpelly, Geol. Soc. Amer., XVI (1908), 167; J. Barrell, Jour. Geol., XVI 
(1908), 167. 
