34 QUEBEC GROUP. 



than 1,000 feet, but the Group at no single locality displays so great a thickness. 

 From Missouri the Group extends southerly across Arkansas into San Saba, Llano, 

 McCulloch, Menard, Mason, and Lampasas Counties, in Texas, where the maximum 

 thickness is more than 400 feet. It is exposed in narrow belts in the Appalachian 

 chain from New York and New Jersey to Tennessee and Georgia, but has not been 

 very clearly distinguished in the mountain regions of the West. 



65. It is said this Group in some localities graduates into the Quebec ; but on 

 the other hand it is claimed the Quebec belongs to the Taconic System, and is below 

 the Potsdam. It is certain many of the rocks referred to the Quebec Group 

 belong to the Taconic, and some of them may belong to the Calciferous or the 

 Chazy, or may form passage beds from one to the other. The oldest known 

 Lamellibranchiata are found in this Group. Among the fossils having the greatest 

 distribution, and which are most characteristic, we may mention Ophileta complanata, 

 0. uniangidaris, Holopea turgida, H. dttwula, and Orthoceras primigenium. Pleuroto- 

 maria canadensis and Leptena barabuensis occur in this Group and in the Potsdam- 

 Pleurotomaria calcifera, P. postwnia, Holopea dtticida, Helicotoma perstriata, Maclurea 

 matutina, M. sordida, Eccyliomphalus canadensis, Gamardla caleifera, LingvMla 

 manielli, L. irene, Amphion salteri, Bathyurus cordai, B. conicus, and Asaphus canalis 

 have been described from this Group and from the Quebec. These identifications 

 may well be doubted, unless the rocks containing all these species really belong to 

 the Calciferous. 



CHAPTER VI. 

 QUEBEC OROUP. 



66. THE Quebec Group was first characterized and its position between the 

 Calciferous and Chazy asserted, upon palseontological evidence, in 1862, by Prof. 

 Billings. His position was supported by the Canadian Geology in 1863, and in 

 Decade 2 of a later date. The limits of the Group are still a subject of discussion, 

 and part of the rocks originally referred to it belong to the Upper Taconic ; but 

 another part of them may form passage beds from the Calciferous to the Chazy, 

 and occupy a position which warrants the name of an independent Group. The 

 name was derived from the city of Quebec, where it was subdivided into the Levis, 

 Lauzon, and Sillery divisions. The Levis was named from Point Levis, where it 

 is fossiliferous, and has a thickness of 6,145 feet; the Lauzon from Lauzon, where 

 its thickness is 4,000 feet, and it is non-fossiliferous ; and the Sillery from Sillery 

 Cove, where it is 2,000 feet thick and almost barren of fossils. The Lauzon 

 division is below the Levis, and, from fragments of fossils found in pebbles, it has 

 been since ascertained that it belongs to the Upper Taconic. A great fault at the 

 Island of New Orleans and another near the Falls of Montmorency, with lesser faults, 

 are said to account for the erroneous reference of this division to the "Quebec. It 

 was supposed at one time that the Sillery and Lauzon were upper members of the 

 Quebec Group ; but both of them belong to the Upper Taconic. 



67. The Group has been traced from Vermont to Newfoundland, a distance 

 of 1,000 miles, and the Levis division noted at several localities, where it consists 

 of a variety of shales, with some sandstones and conglomerates, distinguished by 



