532 INDEX TO THE STRATIGEAPHY OF NORTH AMERICA. 



Knight's article ^"^ contains a very detailed section, measured "in the vicinity 

 of Red Mountain," from the pre-Cambrian granite on which the red beds rest. The 

 section shows the tjrpical variations of sandstone and conglomerate, prevailingly red 

 or reddish. At 728 feet from the base occurs a fossiliferous layer of "grayish to 

 reddish sandstone containing the following genera of fossils: Allorisma, Pleuro- 

 phorus, Bellerophon, Myalina, Aviculopecten, Dentalium (?), Pleurotomaria (?), 

 several small gastropods, and some remains of vertebrates." Knight says: 



The genera [in the fossiliferous layer in his section] are so characteristic that it is not neces- 

 sary to discuss their geological position; they belong to the Paleozoic and resemble to a marked 

 degree the fossils of the Kansas and Nebraska Permian. This places all the strata below the 

 fossiliferous band in the Paleozoic. There remains a formation of about 800 feet in thickness 

 [total 850 feet as measured, comprising red sandstone, shales, and gypsum beds], with the 

 gypsum beds at its base, ia a questionable position, and some may wish to retain these beds in 

 the Triassic. 



On the evidence of the fauna found by Knight 850 feet below the top, and the 

 vertebrate remains collected by Williston near the top, we must conclude that the 

 passage from Permian to Upper Triassic occurs in the upper half of the red beds. 



K 18. CONNECTICUT AND MASSACHUSETTS. 



The Triassic of the Connecticut Valley belongs to the Newark group. (See 

 pp. 522-527.) Davis ^^ discussed the conditions of deposition. Emerson ^^^ classi- 

 fied the strata and described them in detail, particularly with reference to their 

 occurrence in Massachusetts. He says : 



The Triassic rocks have been divided by the author in an earlier publication as follows : 



1. The Sugar Loaf arkose, or the sandstone and conglomerate made up of the debris of 

 granite. 



2. The Mount Toby conglomerate, or the coarse conglomerate made up of large schist and 

 quartzite pebbles. 



These two numbers are, speaking generally, the west and east shore deposits. 



3. The Longmeadow brownstone, or the red sandstone generally marked by so-called 

 fucoidal forms, which are probably concretions. 



4. The Chicopee shale, or the calcareous red shale. 

 These two are the offshore and central beds of the series. 



5. The Granby tuff, or the diabase tuff. 



6. The Holyoke and Deerfield diabase beds. 



7. The Black rock volcanic necks and the posterior diabase beds. 



The last three distinctions cover the fragmental, interbedded, and intrusive occurrences 

 of the diabase, respectively; except that the posterior sheet is placed with the injected necks, 

 with one of which it is directly cormected. 



Russell ^ considered these particular strata in comparison with those of New 

 Jersey and other localities where the Newark occurs. 



In the Pomperaug VaUey in western Connecticut is a small outlier of the Newark 

 group which has been described in detail by Hobbs, ^^^ who distinguishes the following 

 formations in descending order: 



Posterior shales. 

 Main basalt sheet. 

 Anterior shales. 

 Anterior basalt sheet. 

 South Britain conglomerate. 



