132 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



14. Gray limestone conglomerate; the matrix, weathering to a brown in some parts, is probably 



dolomitic 30 



15. Gray, drab-weathering sandstones and shales, the sandstones slightly calcareous 300 



16. Dark-gray and green shales, with thin bands of gray quartzite and occasional thicker beds 



of drab-weathering sandstone, some of them being lenticular masses; the dark shales 

 appear in some parts to pass into black 900 



17. Red and green shales, the red prevailing, interstratified with occasional thin layers of gray 



hard sandstone or quartzite, and a few of gray hard limestone; some of the bands of shale 

 are of a deeper red than the general mass, approaching a maroon color. Toward the top 

 of the equivalents of these shales, at Cape Rouge, there occur a small Lingula and Obolella 

 pretiosa; the thickness of the deposit is from 1,500 feet to 1,000 



5,025 



The strata from 1 to 17 are in ascending order, provided they are not inverted, of which 

 we have no evidence unless it be the occurrence of an Obolella [not Obolella Walcott] in the 

 red shales. Several species of this genus occur in the Potsdam group, and one in what is con- 

 sidered the equivalent of the Calciferous portion of the Quebec group, at Troy, in New York. 

 The genus being only recently established, it is not yet certain of what value it may be in deter- 

 mining the horizon. For the purposes of generalization, in describing the Quebec group, the 

 series will be considered an ascending one; not so much, however, with the view of asserting the 

 order of the strata as to render more intelligible the facts connected with their geographical 

 distribution. 



It has since been shown that the sequence is inverted and also that errors in 

 correlation arose from the failure to distinguish between fossils collected from the 

 pebbles of the limestone conglomerates and those from the matrix. The extension 

 of the term "Quebec group" to strata of widely differing ages led to its abandon- 

 ment. The long controversy which led to this result and the detailed facts as 

 finally ascertained are given in the report by Ells.^" Walcott^'" reviewed the 

 evidence with Ells in the field and discussed EUs's report, adding thereto his own 

 observations. He says: 



When first reading the description of the Point Levis rocks in 1874, I was puzzled by the 

 mixing of the faunas in the lists published by Mr. Billings and the statement made by Sir Wil- 

 ham E. Logan, that the fossils were from the matrix. On reaching Quebec, in August, 1889, 

 I took the first opportunity to examine the lowest bed of hmestone conglomerate back of 

 St. Joseph de Levis and northwest of the CathoHc Cemetery. Dr. EUs accompanied me. 

 As we crossed the ridge I picked up a loose bowlder full of Potsdam or Upper Cambrian fossils. 

 A second bowlder was found embedded in the matrix and then several more, some of which 

 were 3 feet in diameter. The matrix is a hard gray impure limestone that occurs at this point 

 in a sohd band, that we traced 500 feet or more. In the matrix I found the Calciferous fauna 

 was represented by OboleUa sp.?, Orthis sp..?, Camerella calcifera Bilhngs, EcculiompTialus canor- 

 densis BiUings, Ecculiomphalus intortus Bilhngs, Ophileta complanata Vanuxem, Pleurotomaria 

 canadensis BiUings, Pleurotomaria sp.?, Orthoceras, 4 sp. undet., Ceraurus? apoUo Billings, 

 deraurus eryx Billings, Bathyurus Mtuherculatus BiUings, Bathyurus quadratus Billings. 



In a bed of limestone 50 feet higher in the section I found, in addition to the preceding, 

 the foUowing: Bathyurus cordia BiUings, Bathyurus oUongus BiUings, Amphion caleyi Billings. 

 In the succeeding band of limestone conglomerate Orthis porambonites Pander occurs. 



A large number of specimens were obtained from the bowlders embedded in the limestone 

 containing the fossils of Calciferous age, among which I have identified Camerella calcifera BU- 

 luigs(?), Agnostus americanus BiUings, Dicelocephalus magnificus Billings, D. oweni B illin gs, 

 D. belli Billings, Arionellus suhclavatus Billings, Menocephalusf sedgwicJci Bilhngs, and Elsenurus 

 illsenoides BiUings (sp.). Other species occur, jjut the preceding Hst is sufficient to indicate the 

 fauna of the Upper Cambrian or Potsdam zone. 



