164 GEOLOGICAL SURVEY OF THE TERRITORIES. 



thickness, with its usual yellow chalky character ; the usual Ostrea 

 congcsta occurs in great abundance. Immediately along the line of the 

 railroad no indications of No. 3 have ever been observed. Nowhere in 

 the Laramie plains are any of the subdivisions of the cretaceous group, 

 well defined. These beds occupy the colntry along the line of the 

 road from Laramie City nearly to Como Station, a distance of sixty 

 miles ; at this point the red beds and the true Jurassic rocks are 

 brought to the surface, over a restricted area, by means of an anticlinal 

 which forms a valley through which the road passes. The strata in- 

 cline from either side. The south side of the road exposes the most 

 complete series of beds ; a high ridge is composed of Jurassic beds, 

 mostly capped with the sandstones of No. 1, while as far as the eye 

 can reach to the southward the low. wave-like ridges of No. 2 can be 

 seen. Towards the southwest, the anticlinal valley seems to close up, 

 but to the northeastward it expands indefinitely, and extends, no doubt, 

 to the Laramie range. 



From a point about ten miles west of Como to St. Mary's Station, a 

 distance of fifty miles, the tertiary coal beds, with the sands, sandstones, 

 and clays peculiar to them, occupy the country. The most important 

 coal mines are located at Carbon ; no shells have ever been observed 

 in connection with the coal, but thousands of impressions of deciduous 

 leaves are found. It is an important point to fix the age of the coal 

 beds in any one locality. So far as we can determine, the coal beds of 

 the Laramie plains are of eocene age, although the plants are more 

 closely allied to those of the miocene period in the Old World. 



In the vicinity of Elk Mountain, along the Overland stage road, in 

 beds which I regard as belonging to the older tertiary, and holding a 

 Xiosition near the junction of the tertiary and cretaceous, and nearly or 

 quite on a parallel with the lower tertiary beds near Denver, Colorado, 

 1 found a quantity of fossil leaves, among which Dr. Newberry identi- 

 fies Platanus Raydeni, Quercus aceroides, Magnolia tenerafolia, with frag- 

 ments of Gornus and Khamnus. The same species occur in the upper 

 portion of the coal series on the west side of Bridger's Pass. At Carbon 

 Populus cuneata, P. Nebrascensis, and Platanus Haydeni, are very abun- 

 dant. From St. Mary's Station to Eawlings' Springs, a distance of thirty 

 miles, the road passes over rocks of cretaceous age ; although on the 

 hills on either side remnants of the coal strata may be found. About 

 two miles west of this point the coal beds begin to appear again, and at 

 Separation, Platanus Haydeni, Gornus acuminata, with other undeter- 

 mined species of plants, occur. This point forms the eastern rim of a 

 basin which extends about one hundred and ten miles to the westward. 

 A new group comes in which I have named the Washakie Group, from 

 the fact that near this station are beds of calcareous sandstone and lime- 

 stone, composed of an aggregate of fresh-water shells. As they are 

 mostly casts it is difficult to identify the species, but Mr. Meek has 

 named the most abundant kind Unio WashaJceei. Soon after leaving Bitter 

 Creek Station the coal strata of eocene age rise to the surface from be- 

 neath the miocene beds of the Washakie Group with a reversed dip. 

 Here we find numerous beds of coal, and in the rocks above and below 

 the coal are great numbers of impressions of leaves, and in the clay 

 seams of oyster shells of several species. At Black Buttes Station, eight 

 hundred and fifty miles west of Omaha, we found Sabal Campbelli, Bham- 

 nus elegans, Gornus acuminata, Quercus aceroides, Tilia antiqua, with 

 other undescribed species. At Point of Bocks, fourteen miles farther 

 west, Platanus Haydeni, P. Nebrasccmis, Gornus acuminata, Magnolia 

 tcnerafolia,occi\T. At Hallville the black slaty clays, forming the roof of one 



