Mesozoic and Cccnozoic Geology and PalcBontoloyy. 35 



Creosaurus atrox, Laosaurus celer, L. gracilis, Dryolestes 2Jriscus, 

 Pterodactylus montanus. 



In 1879, Geo. M. Dawson* found on Nicola Lake, in British Colum- 

 bia, a great formation built up almost exclusively of volcanic products, 

 which have frequently a characteristically green color, and hold toward 

 the base beds of gra}^ subcrystalline limestone, intermingled in some 

 places with volcanic material, and holding occasional beds of water- 

 rounded detritus, which he regarded as of Triassic Age. 



Dr. C. A. White described,! from the Jurassic of southeastern Idaho, 

 Terebratula semisimplex^ Aviculopecten pealei, A. altus, Jleekoceras 

 aplanatum, M. gracilitatis, 31. mushhachaniim, and Arcestes cirratus. 



Prof O. C. MarshJ described, from the Jurassic of the Rocky Moun- 

 tains, Stylacodon gracilis, Ctenacodon serratus, Dryolestes arcuatus, 

 Tinodon, robustus, T. lepidus, Brontosaurus excelsus, caniptonotus 

 ampins, C. dispar, Ccelurus jragilis, and Stegosaurus tmgulafAis. 



And Prof. E. D. Cope§ described, from the Jurassic of Colorado, 

 Camarasaurus leptodirus and Hypsirhopus seeleyanus. 



Jurassic strata were determined at Cook's Inlet, in Alaska, as early 

 as 1848, and Grewingk described,! from this place, Ammonites wos- 

 nessenski, and identified A. hiplex, Belemnitella paxillosa, and Unio 

 liasinus. And in 1857, Jurassic strata were determined at Point Wilkie 

 on Prince Patrick Land, far north of British America. It was from 

 this place that Capt. McClintock collected the fossils described by 

 Prof. Haughtou^ as Ammonites maccUntocki and Ilonotis [Avicula) 

 septentrionalis. 



In taking a general view of the Triassic and Jurassic strata, we see 

 them in the eastern part of the continent consisting of narrow belts, 

 having an immense thickness. The thickness in the Connecticut Val- 

 ley is but little short of four miles, while in New Jersey it exceeds five 

 miles. Israel C. Russell has argued that the physical history of these 

 beds, in New Jersey and Connecticut, tends strongly to show that the 

 two areas are the borders of one great estuary deposit, the central por- 

 tion of which was slowl^^ upheaved, and then removed by denudation. 

 That the trap sheets were derived from a reservoir beneath the estuary 

 deposits, and represent in part the force that 'caused the upheaval. 

 The outburst of trap must have been the closing event of the Triassic 

 changes, and have occurred after the sedimentary beds had been up- 



* Geo. Sur. Can. t Bull. U. S. Sur., Vol. 5, No. 1. 



X Am. Jour. Sci. & Arts, 3d ser., vol. 18. g Am. Nat., vol. 13. 



OVerhandlungen der Russisch-Kaiserlichen mineralogischen Gesellseliaft zuSt. Petersbourg. 

 1[ Jour. Roy. Dub. Soc, Ireland. 



