254 Tertiary. 



G. T. Bettan}^* described, from the Miocene of Joliii Day's rivei', 

 Oregon, 3ferycoGh(B7'us leidyi, and M. temporalis. 



J. A. AUenf described, from the lead crevices and superficial strata 

 ofth-elead region of Wisconsin, Iowa, and Illinois, of supposed Plio- 

 cene age, Canis mississippiensis, and Cervus lohitneyi. Charles M. 

 Wallace found flint implements in the stratified drift, near Richmond, 

 Virginia, which he referred to Post-pliocene age. 



In 1877, Dr. F. M. EndlichJ found the Puerco Group forming the 

 lowest member of the Wasatch, and well developed in southern Colora- 

 do. It was best observed on the Lower Animas, where it consists of 

 1,000 to 1,200 feet of variegated shales and marls. At the base, they 

 are a mudd}'^ green, changing into yellow or almost blue. Farther up, 

 pink, pale orange, lilac, and reddish colors predominate, varied by in- 

 terstrata of white or light 3^ellow. Thin beds of sandstone nierel3^ of 

 local occurrence, however, separate these beds; not forming definite 

 recognizable horizons. Farther east, these variegated marls gradual- 

 ly change into shales and sandstones, so that they are no longer 

 characteristic. Above them there occur 1,000 feet of yellow to brown 

 sandstones and shales. As a rule the beds of sandstone are heavy, 

 weathering massively, but they frequently show but^ small thickness, 

 and are interstratified with yellow and grayish shales. In some of the 

 shales, indications of coal may be observed, but nowhere throughout 

 the San Juan region was anj^ vein found that would have been 

 sufficiently large, or of good quality to be worked. 



All the lower canons of the San Juan drainage, and that of the river 

 itself, are formed by this series of sandstones, and others superin- 

 cumbent. Over the entire region which they cover, they are uniform, 

 both in occurrence and in lithological character. Their ver^'^ small 

 dip to the south, 2° to 4°, and their total thickness of 3,000 feet, en- 

 ables them to extend over a large area of country. 



Dr. B. F. Mudge found the Pliocene strata of Kansas resting direct- 

 ly upon the Cretaceous. The material of the Pliocene deposits con- 

 sists of sandstone of various shades of graj^ and brown, occasionall,y 

 whitened by a small admixture of lime. The lower strata are usually 

 composed of finer sand than the upper, and much more loose and 

 friable in their texture. The overljnng beds are of coarser ingredients, 

 consisting of water-worn pebbles of metamorphic rocks, quartz, green- 



=•' Quar. Jour. Geo. Soc. Lend., vol. xxxii. 

 T Am. Jour. Sci. and Arts, 3d ser., vol. xi. 

 t 9th Ann. Rep. U. S. 'leo. Sur. Terr. 



