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Age Relations oe Rocks of Cobalt and Adjacent Areas. 

 PALEOZOIC 



SILURIAN 

 Niagara 



(Great unconformity.) 



EOZOIC OR PRE= 

 CAMBRIAN 



LATER DIKES 

 NIPISSING DIABASE 



(Intrusive contact.) 



COBALT SERIES 



(Unconformity.) 



LORRAIN GRANITE 



(Intrusive contact.) 



LA1Y1PROPHYRE DIKES 



(Intrusive contact.) 



TEMISKAMING SERIES 



(Unconformity .) 



KEEWATIN COMPLEX 



Prominent outcrops of Niagara limestone, 

 with basal conglomerate and sandstone, occur 

 on some of the islands and the shores of the 

 north end of lake Temiskaming, 



Aplite, diabase, basalt. 



This diabase, which is of such great interest 

 in connection with the cobalt-silver veins, is 

 believed to be of Keweenawan age. Certain 

 aplite dikes are genetically connected with 

 the diabase. 



The Cobalt series includes conglomerate, 

 greywacke and other fragmental rocks. 



This granite occupies a considerable part of 

 the township of Lorrain and has large ex- 

 posures elsewhere in the vicinity of lake 

 Temiskaming. 



Lamprophyre dikes are to be seen near some 

 of the mines at Cobalt. 



Like the Cobalt series, the Temiskaming 

 consists of conglomerate and other fragmental 

 rocks. 



The Laurentian, gneiss and granite, which 

 in age lies between the Keewatin and Temis- 

 kaming, is absent in the Cobalt area proper, 

 but is found in the surrounding region. 



Under the heading Keewatin are grouped 

 the most ancient rocks of the region. They 

 consist essentially of basic volcanic types, 

 now represented by schists and greenstones, 

 together with more acidic types, such as 

 quartz-porphyry. 



With the Keewatin are included certain 

 sed'ments, such as iron formation or jaspilyte, 

 dark slates and greywackes, which probably 

 represent the Grenville series of southeastern 

 Ontario. 



Certain dike rocks that are grouped with 

 the Keewatin may be of post-Temiskaming 

 age, but since they have not been found in 

 contact with the Temiskaming series their 

 age relationships are unknown. 



