466 



REGINALD E. HORE 



rials might have been brought down, nor is there good reason to believe 

 that such hills existed in Huronian times. The nearest outcrops of 

 Laurentian rocks from which many of the bowlders may have been 

 derived are some miles distant. Many of the large bowlders are quite 

 unlike any rocks which have been found in place in the district. 

 Evidently ice was the most competent agent to bring such materials 

 to their present position, and to deposit them in such a heterogeneous 

 manner. 



Fig. 8. — Huronian conglomerate, Trethewey Mine, Cobalt, Ont. Shows stratified 

 and unstratified portions. Such well-banded portions are of quite small extent as 

 compared with the unstratified. One of the streaks contains distinctly angular 

 fragments. 



At Temagami the conglomerate lies on Keewatin schists and at 

 its base contains numerous fragments of them. The conglomerate 

 also contains numerous rounded and subangular bowlders of rocks 

 not found close by. The underlying rock presents a fairly fresh but 

 not a smooth surface. The matrix of the basal conglomerate contains 

 numerous well-formed rhombohedra of siderite, and similar crystals 

 are abundant in shale and quartzite beds in the conglomerate. They 

 were evidently derived by weathering from the adjacent iron formation 

 and the crystals were growing freely contemporaneous with the 

 mechanical deposition of clay, sand, and bowlders. It is probable 



