SQ A. WINCHELL — A LAST WORD WITH THE HURONIAN. 



Page. 



Union of two Systems in Minnesota and the Northwest 109 



Views of Logan and others 109 



Views of Irving 110 



Objections to Irving's Hypothesis 111 



Views of Lawson 113 



Personal Observations in the Echo Lake Kegion 114 



The Region studied and Murray's Views concerning it 114 



The Succession on Echo Lake 116 



Microscopic Characters of Echo Lake Rocks 121 



Conclusion 123 



Two Systems of Rocks in the Huronian Region 123 



The Name " Huronian " must be restricted to the upper System 124 



Citations from the Founders Touching the Typical Area. 



In entering on a fresh discussion of the Huronian system * it appears 

 desirable to show, by documentary citations, what were the conceptions of 

 the founders of the system. 



Murray^s earliest Description. — The term " Huronian " was based on the 

 name of Lake Huron, along whose northern shores, and contiguous thereto, 

 the rocks are located to which the name was first applied. The earliest 

 description of these rocks was by Alexander Murray, in 1848.t He says : 



" The older groups observed consist, firstly, of a metamorphic series, composed of 

 granitic and syenitic rocks in the forms of gneiss, mica slate and hornblende slate, 

 and, secondly, of a stratified series, composed of quartz rock or sandstones [J], conglom- 

 erates, shales and limestones, with interposed beds of greenstone. * * * On a 

 cluster of small islands ^ * * granite was found breaking thrdugh the quartz 

 rock. The color of the rock was red. On one of the islands, quartz beds on opposite 

 sides of the granite were observed to dip in opposite directions, north on the north 

 side and south on the south side, at an angle of 70° or 80°; and in another of the 

 islands the quartz rock and granite were seen in juxtaposition, the former reclining 

 on the latter." 



The chieJf importance of the last statement quoted consists in the evidence 

 afforded that along the immediate shore the higher members only of the 

 series rest in contact with the older gneiss, and do not constitute deposits 

 immediately successive to it in a chronological sense. 



Logan's Descidption. — In a report made the same year by Logan these 

 rocks were compared with those previously seen by himself § on the south of 



*ln this memoir no attempt has been made to employ the nomenclature which stands approved 

 by the Int^-rnational Geological (Congress, because, as an American geologist, the writer feels that 

 the question has not yet been settled by an adequate representation of the geologists of the civil- 

 ized world. 



t Report of Progess of the Geological Survey of Canada for 1847-48, pp. 107-113. 



t Afterward g.-nerally called quartzites. 



§ Report of Progress lor 1845-46, p. 67. 



