Veatch — Localities of Supposed Jurassic Fossils. 457 



Art. XLIII. — Age and Type Localities of the Supposed Juras- 

 sic Fossils collected North of Fort JBridger, Wyoming, hy 

 Fremont in 18J±3 /* by A. C. Veatch. 



On August 19, 1843, having turned north from Fort 

 Bridger on the Oregon Emigrant Road and passed over Muddy 

 Fork, or Big Muddy (which he refers to as " a salt creek about 

 15 feet wide") near the present site of Carter, Uinta County, 

 Wyo., Fremont reportsf that he crossed a high ridge " and 

 descended upon one of the heads of Ham's Fork called Muddy, 

 where we made our midday halt. In the river hills at this 

 place I discovered strata of fossiliferous rock having an oolitic 

 structure, which in connection with the neighboring strata 

 authorizes us to believe that here on the west side of the Rocky 

 Mountains we find repeated the modern formations of Great 

 Britain and Europe which have hitherto been wanting to com- 

 plete the system of North American geology. In the after- 

 noon we continued our road, and searching among the hills a 

 few miles up the stream and on the same bank I discovered 

 among alternating beds of coal and clay, a stratum of white 

 indurated clay containing very clear and beautiful impression s 

 of vegetable remains." 



These specimens were referred to James Hall, who described 

 them:]: and gave the following additional details regarding the 

 locality, evidently based largely on Fremont's notes.§ 



" Longitude 111°, latitude 4i|°, Muddy River. — These speci- 

 mens are of a yellowish gray oolitic limestone, containing turbo, 

 cerithium, &c. The rock is a perfect oolite ; and, both in 

 color and texture, can scarcely be distinguished from speci- 

 mens of the Bath Oolite. One of the specimens is quite cry- 

 stalline, and the oolitic structure somewhat obscure. In this 

 instance, the few fossils observed seem hardly sufficient to 

 draw a decisive conclusion regarding the age of the formation ; 

 but, when taken in connection with the oolitic structure of 

 the mass, its correspondence with the English oolites, and the 

 modern aspect of the whole, there remains less doubt of the 

 propriety of referring it to the Oolitic period. A further col- 

 lection from this interesting locality would doubtless develop 

 a series of fossils, which would forever settle the question of 

 the relative age of the formation. 



* Published with the permission of the Director of the Geological Survey. 



f Fremont, Gapt. J. C, Rept. of Exploring Expedition of the Rocky Moun- 

 tains in the Year 1842, and of Oregon and Northern California in the years 

 1843-44, 28th Congress, 2d Session, House Executive Document No. 166, 

 1845, p. 131. 



% Ibid. , pp. 304-310. § Ibid. , pp. 297-298. 



Am. Jour. Sci. — Fourth Series, Vol. XXI, No. 126.— June, 1906. 

 32 



