llesozoic and Ccenozoic Geology and Paksontology. 25 



ceeded b}- a quartzite belonging to the Dakota Group, having a thick- 

 ness of 150 feet. At Little Tliorapson's creek it consists of soft granite 

 sandstones and conglomerates below, followed by red, shal}^ and mas- 

 sive sandstones above, and reposes upon the smoothed and often irreg- 

 ular surface of Archaean rocks. It has a thickness of 750 feet. It thins 

 out north of Golden City, where it has a thickness of scarcely 400 feet, 

 but rapidly thickens in its extension southward to where the South 

 Platte debouches from the mountains; here it attains a thickness of 

 1.600 feet. Dr. A. C. Peale's section through Pleasant Pai'k repre- 

 sents its thickness at 1,580 feet, and from Glen Eyrie eastward to 

 Camp creek, 1,280 feet. 



A section of the Jurassic rocks, taken by Wm. H. Holmes near Saint 

 Vrain's Creek, gave a thickness of between 400 and 500 feet; and an- 

 other in Bear Canon, 870 feet; another near Ralston creek, 660 feet; 

 and another near Bear Creek, 770 feet. Dr. A. C. Peale's section 

 through Pleasant Park furnishes a thickness of about 461 feet, and 

 from Glen Eyrie eastward to Camp Creek, 405 feet. 



Prof. E. D. Cope* detected the first vertebrate fossils in the Trias of 

 the Rocky Mountains of New Mexico, including carnivorous Sauri- 

 ans and Unionidffi, the latter indicating a lacustrine deposit. 



In North Carolina f there are two narrow fringes of an eroded and 

 obliterated anticlinal which belong to the Triassic; the smaller or 

 Dan river belt, from 2 to 4 miles wide, following the trough-like valley 

 of that stream, about N. 65° E. for more than 30 miles, to the Virginia 

 line, and then extending into Virginia about 10 miles; the other, the 

 Deep river belt, extending in a similar trough 5 to 15 miles wide (and 

 depressed 100 to 200 feet below the general level of the country), from 

 the southern boundary of the State in Anson county, in a N. E. direc- 

 tion, to the middle of Granville count}', within 15 miles of the Virginia 

 line. They are separated, therefore, by a swell of country 75 to 100 

 miles wide,, which rises along its topographical axis to 800 or 900 

 feet above the sea, the troughs themselves having respectively an 

 elevation of 500 to 600 feet, and 200 to 300 feet. The belts are 

 convergent in the direction of the Triassic beds of Virginia, with 

 which they were doubtless once connected (as well as with some 

 small intervening outliers) in one continous formation. 



The dip of the Dan river beds is about 35° N. W. (20° to 70°) and 

 those of Deep river, 20° S. E. (10° to 35°). The rocks are sandstones, 



-Proo. Am. Phil. Soc. ■-. 



t Kerr's Geo. of N. Carolina, 1875. Emmons 'Jeo. Sur. 1856. 



