90 Mr, T, Sterry Hunt 



the S. E., the rocks of this group are made to overlap the Hud- 

 son River formation. " Sometimes it may overlie the overturned 

 Utica formation, and in Vermont, points of the overturned Tren- 

 ton appear occasionally to emerge from beneath the overlap.*'* 

 This great dislocation is traceable in a gently curving line from 

 near Lake Charaplain to Quebec, passing just north of the fort- 

 ress ; thence it traverses the island of Orleans, leaving a band of 

 higher strata on the northern part of the island, and after passing 

 under the waters of the Gulf, again appears on the main land 

 about eighty miles from the extremity of Gaspe, where on the 

 north side of the break, we have as in the island of Orleans, a 

 band of Utica or Hudson River strata. To the south and east of 

 this line the rocks of the Quebec group are arranged in long, 

 narrow, parallel, synclinal forms, with many overturn dips. These 

 synclinals are separated by dark gray and black shales, with lime- 

 stones, hitherto regarded as of Hudson River age, but which are 

 perhaps the deep-sea equivalent of the Potsdam. 



The presence of conglomerates and sandstones, alternating with 

 great masses of fine shales, indicates a period of frequent distur- 

 bances, with elevations and depressions of the ocean's bottom,while 

 the deposits of dolomite, magnesite, travertine and highly metal- 

 liferous strata show the existence of shallow water, lagoons and 

 springs over a great area and for a long period between the forma- 

 tion of the upper and lower shales . We may suppose that while 

 the Potsdam sandstone was being deposited along the shores of 

 the great palaeozoic ocean, the lower black shales were accumula-^ 

 ting in the deeper waters, after which an elevation took place, and 

 the magnesian strata were deposited, followed by a subsidence 

 during the period of the upper shales and Sillery sandstones. 



Associated with the magnesian strata at Point Levis and in 

 several other localities in the same horizon of the Quebec group, 

 an extensive fauna is found, of which 137 species are now known, 

 embracing more than forty new species of graptolites, which have 

 been described by Mr. James Hall in the report of the Geological 

 Survey of Canada for 1857, and thirty-six species of trilobitea 

 described by Mr. Billings in the Canadian Naturalist for August 

 1860. These species are as yet distinct from anything found in 

 the Potsdam below or the Birdseye and Black River above ; 



* See Sir William Logan's letter to Mr. Barrande, Canadian Naturalist 

 for Jan. 1861, and Am. Journal, of Science (2) x xxl. 216. 



