36 THE ROYAL SOCIETY OF CANADA 



The three-foot, massive bed of micaceous clay at the bottom of 

 the above section was the only one sampled for testing, as it looked 

 the least promising from a refractory point of view. It, however, 

 proved to be a fire-clay. It was assumed that all the upper beds were 

 fire-clays as well as the ones accompanying the lignite which are 

 similar to those occurring just below Long Portage. 



Borings made in this locality in 1910 by Prof. M. B. Baker show 

 that the fire-clays reach a depth below the river of 16 feet, but no 

 lignite appears to have been encountered below the seam which out- 

 crops on the river bank.^ The bottom of the clay was not reached in 

 the borings so that the material underlying it is unknown. 



The greatest thickness of Cretaceous deposits recorded was that 

 reported on by Mr. H. A. Calkins, C.E., who examined the large 

 deposit on Missinaibi river in 1913 for the Montreal syndicate that 

 staked the claims upon it. Mr. Calkins made a series of borings 

 with a Standard earth auger equipment, and in the hole farthest 

 removed from the river bank he found red and white clay below the 

 glacial drift at a height of 74 feet above the river level. As the white 

 and red clay can be seen in the bed of the river at this point a con- 

 siderable amount would have to be added in order to obtain the entire 

 thickness so that it is probable that there is in the neighbourhood of 

 100 feet of Cretaceous measures intact in this region. The above 

 data were taken from Mr. Calkins' report, a copy of which was sent 

 to the Department of Mines. 



Distribution of Cretaceous Deposits 



It is quite probable that Mesozoic clays, sands, and lignites were 

 formerly widespread in northern Ontario, but a long period of pre- 

 Glacial erosion, inter-Glacial erosion, and two distinct periods of 

 glaciation in Pleistocene times have well nigh obliterated them, and 

 now only small detached patches are found at certain points where 

 the rivers have cut down through the overlying glacial debris deeply 

 enough to expose them. Outcrops of these rocks are known at present 

 at five places on the well travelled river routes, and there may be 

 many others on smaller and less travelled streams. 



The known outcrops are all situated, with one exception, from 

 one to eight miles north of the northern border of the pre-Cambrian 

 upland. The distance from the outcrops on the Mattagami to those 

 on Missinaibi river is 40 miles, and it is quite possible that Cretaceous 

 deposits were formerly continuous over the intervening area. 



1 Ontario Bureau of Mines, Vol. XX, Part I, p. 236. 



