JURA-TRIAS. 53-5 



Santa Fe Railroad. The next hill east of the "Hogback" lising nearly 200 

 feet high, is covered with rounded boulders of rocks resembling those of the 

 Arch^an above the Springs. 



I observed no fossils in the sandstone forming the "Hogback"; Prof. H. 

 assigns it to No. i Cretaceous. The rocks next above and on the east are chiefly 

 dark shales. The sandstone is also well represented along the valley of the 

 Moro on the line of the Atchison, Topeka & Santa Fe Railroad. 



It may be that Prof. Hayden has traced these so cilled Jura-Trias rocks a 

 long distance and found fossils in them. 



Before reaching Sherman on the Union Pacific Railroad we observe rocks 

 resembling those of Las Vegas and they are probably of the same age. Approach- 

 ing Laramie City the Red Buttes are prominent, as are also the red beds to be seen 

 twenty-five miles off" to the southwest which I noticed in the August number of 

 the Kansas City Review. I here produce the section therein : 

 I. — 200 feet White beds on hill-top. 

 2. — 1000 feet of Red beds. 

 3. — 36 feet of White gypsum. 

 4. — 100 feet of Red and Gray beds. 



In these rocks I observed no fossils. Hayden and most of the U. S. Geologists 

 speak of these red beds occupying a narrow belt east of the mountains and in 

 juxtaposition thereto, extending from north of the Union Pacific Railway 

 southwardly into New Mexico. They also call them Jurassic and Triassic or 

 Jura-Trias, but find no fossils in the Trias east of the mountains, excepting on 

 Gallinas Creek, New Mexico, the Black Hills, mouth of Judith River, heads of 

 Yellowstone, Missouri and Wind Rivers. I give the following as the Bibliography 

 of the Jura-Trias in the western States and Territories : 



Prof. Jules Marcon was probably the first who spoke of the existence of the 

 Jurassic and Triassic in western America. From June, 1853, to March 1854, he 

 accompanied Capt. Whipple, U. S. Army, on a tour from Fort Smith, Ark., via 

 Albuquerque, New Mexico, to Los Angeles, California. A portion of his route 

 was reviewed and published in Pacific Railway Reports. His own work is fully 

 detailed in his Geology of North America, Zurich, Switz. , 1858. Accompany- 

 ing this we find a Geological Map of North America on which is colored an ex- 

 tensive area of New Red and also of Jurassic. A considerable area of this has 

 since been referred by American geologists to the Cretaceous. He 'ncludes 

 1500 feet of strata observed on the Llano Estacado as Triassic, This is probably 

 the equivalent of Hayden's Dakotah Group^ and may also include part of No. 2 

 Cretaceous of Hayden. Prof. Marcon speaks of an extensive development of 

 Triassic between Zuni and the Colorado Chiquito inclosing large fossil trees. 



Of the rocks of Pyramid Mount (Lat. 35, Long. 103° 58') in Llano Estacado, 

 he places the lower beds in the New Red, the upper in the Jura. Prof. Marcon 

 informs us that he submitted the fossils to European geologists and palaeontolo- 

 gists- and they recognized among them GryphcBO, dilatata and Ostrea Marshii and 



VI— 34 



