GEOLOGY OF THE CONNECTICUT VALLEY DISTRICT. 45/ 



constituents are universally common, as explained by Prof. Dana ; so 

 that their presence does not argue a high degree of metamorphism. 



j^F:E'Ei>rjDx:K. to csi^i^tek, iat. 

 TiiE HuROXiAN System. 



On page 267 I have promised at this place to discuss the claims of the Huroniaii 

 system to recognition. It will be done briefly, while our comparisons must extend over 

 a very wide territory. 



In the large geological map of the United States, prepared in conjunction with Prof. 

 W. P. lUake for the Smithsonian Institution, and exhibited in Philadelphia at the 

 Centennial Exposition, seventeen areas of the Huronian system west of the St. Law- 

 rence river are represented, irrespective of those along the Atlantic border. 



The first use of the word Huronian I find is in the Esqidsse Geologiquc du Canada, 

 prepared by T. Sterry Hunt for the Paris Exposition of 1855. It is represented as 

 being a series of grits, schists, limestones, conglomerates, and diorites, reposing un- 

 conformably upon the Laurentian, and lying beneath the Silurian. It is said to hold 

 about the position of the lower Cambrian of Sedgewick. The area from which the 

 name was derived lies upon the north shore of Lake Huron. A section from the Lau- 

 rentian outcrop on the main land opposite Drummond island, and running a little 

 north of west to Lake George, would pass in succession through all the members 

 of the series. I find these overlaid by the St. Peter's (Chazy) sandstone, according 

 to Logan. 



The following is a section of the Huronian rocks from this typical locality, as derived 

 from the geology of Canada, 1863, and the accompanying atlas, wherein the distribu- 

 tion of the several members is clearly represented with colors. 



Feet. 



/. White quartzite, chert, and limestone 2,100 



k. Yellow chert and limestone, 400 



/. White quartzite, ......... 2,970 



//. Red jasper conglomerate, ....... 2,150 



g. Red quartzite with greenstone ; ripple marks, .... 2,300 



f. Upper slate conglomerate, 3,000 



e. Limestone, with diminutive contortions, 300 



d. Lower slate conglomerate, with greenstone, .... 1,280 



c. White quartzite, 1,000 



b. Green chlorite slate, 2,000 



a. Gray quartzite, 500 



18,000 



This typical locality does not enable us to restrict the limits of the system so closely 

 as may be done upon the south side of Lake Superior, in the northern peninsula of 

 VOL. II. 58 



