100 A. WINCHELL A LAST WORD WITH THE HUKONIAK. 



Feet. 

 erally interstratified in the rock, which do not seem confined to any one 

 stratigraphical place 1,280 



3. Quartzite, white, the color sometimes passing into gray, principally fine- 

 grained, but great masses become vitreous quartzite ; sometimes, also, 

 coai'se- grained and passing to the character of a conglomerate, from the 

 presence of pebbles chiefly of white quartz ; the massive beds frequently 

 separated by la^-ers of fine-grained, greenish-gray silicious slate ; green- 

 stones intercalated throughout 1,000 



2. Slates, greenish, red-weathering, chloritic and epidotic ; trap-like beds 



interstratified ? 2,000 



1. Quartzite, gray, thin-bedded in parts ? 500 



18,000 



The foregoing is a careful and excellent description of the various mem- 

 bers of the series of rocks north of Lake Huron, which were embraced in 

 the original Huronian. From personal examination in various portions of 

 the region, the writer can testify to its general accuracy. It is a fair picture 

 of the Huronian as we actually see it. It is a product of long-continued 

 patient industry and physical endurance never surpassed, in a vast and 

 wild expanse of the continental surface, and prosecuted with skill and judg- 

 ment equal to the best standards of similar work in any country. To sug- 

 gest an interpretation required by a much wider range of observations is 

 not to destroy the fabric of Canadian results, but to assist in its completion. 



Two Systems united under the Name "Huronian." 



STRUCTURAL DISCORDANCES IN THE LAKE HURON DIVISION. 



AVe shall first discuss this branch of the question from the evidence of the 

 documents supplying the original facts. We shall then consider the bear- 

 ing of facts of later development, especially such as have come under our 

 personal observation. 



Evidence from the Documents. — Were no records in existence touching the 

 Lake Huron district except such as existed when the term *' Huronian" was 

 proposed, it would be easy to overlook the evidence that the original Hu- 

 ronian was not homogeneous. Without critital examination of Canadian 

 geological literature, the inherent evidence of the confounding of two sys- 

 tems might remain unnoticed. The language employed by Messrs. Logan 

 and Murray implies that no suspicion existed in their minds that the 

 series which they were describing extended over a great geological break ; 

 and in such a state of mind they neglected to dwell upon those facts which 

 in the light of more recent studies must be regarded as intimations, if not 

 proofs, of the duplex character of their system. Nor are the field proofs of 

 its duplex character conspicuous. They are even disguised by the similarity 



