250 INDEX TO THE STRATIGEAPHY OF NORTH AMERICA. 



Lane ^" states his views on. the significance of the stratigraphy in the article 

 already cited, together with details of well records. 



L 17. LAKE TEMISCAMING, ONTABIO. 



The Silurian outlier of Lake Temiscaming, first described by Logan/^^- ^^ has 

 more recently been mapped and discussed in detail by Barlow.^^- ^^ At those points 

 where the formation was deposited on the pre-Cambrian rocks there is a basal con- 

 glomerate, consisting in part of subangular talus blocks, in part of smaller pebbles 

 of the adjacent older rocks in a calcareous cement; The deeper-water deposits are 

 fine-grained yellowish limestone, with some shale and a considerable proportion of 

 chert in some beds. The large collections of fossils from this section represent the 

 Niagaran (including the Clinton) . 



L 18-19. SOXJTHERN QUEBEC. 



Isolated areas of Silurian strata occur in synclines southeast of the St. Lawrence. 

 They are composed chiefly of limestone, characterized by Silurian corals. They lie 

 unconformably upon the Ordovician strata. Detailed local descriptions are given 

 by EUs.^^"'^"*'^^^'' A noteworthy correction of earlier descriptions is the determina- 

 tion of a so-caUed conglomerate of St. Helen's Island, Montreal, as a volcanic 

 breccia "of later date than the Helderberg limestone." 



In the Memphremagog area"^ — 



the formation is characterized by a considerable thickness of hmestone, some of which is graph- 

 itic, while other portions are highly dolomitic and are associated with dolomitic grayish slates. 

 * * * The structure in this area is that of a folded basin resting, on either side of the lake, 

 upon fossOiferous lower Trenton rocks [Magog formation]. The rocks are altered from calca- 

 reous slates and Mmestones to talcose and mica schists or to graphitic crystalline marble, and 

 are cut by numerous dikes, which are often of large size. 



L 19. NEW HAMPSHIRE (LITTLETON). 



In the township of Littleton, in northern New Hampshire, is an occurrence of 

 fossiliferous strata, in part at least of Niagaran age, with possibly slates of Helder- 

 berg age as well. 



Under the heading "Silurian and Devonian strata," Hitchcock*" includes 

 "the Coos mica schist and quartzite, the Niagara limestones, and slates, sand- 

 stones, and argillites." There is no good evidence as to the age of the mica schist. 



The unaltered strata occur in Blueberry Mountain, which is believed to have 

 a synclinal structure. If so, the sequence of formations in ascending order is as 

 follows: Limestone, sandstone, coarse conglomerate, bluish and black slates. 

 Hitchcock *^ reports the following fossils from the limestone : " Favosites hasaltica, 

 F. niagarensis, Zaphrentis, Astrocerium venustum, Halysites catenulatus, Pentamerus 

 nysius, a lingula, crinoidal fragments, a gastropod, Dalmania limulurus, and frag- 

 ments of a Lichas," determined by Billings and Whitfield. 



L 20. NOVA SCOTIA. 



Under the heading " Siluro-Devonian rocks of Digby and Annapolis" (the 

 southwestern counties of Nova Scotia) Bailey*^ gives a detailed account of the slates 

 and intercalated impure limestones which lie along the north side of the intrusive 



