110 Cincinnati Society of Natural History. 



which seem as if grouiirl by the waves, thrown iipo;i the shore and mixed 

 in the sand with fucoidal remains. That this sandstone forms all 

 over and around the Raton mountains, the base of what is called the 

 Lignitic Group, and that it overlies the black shale of the Fort Pierre 

 Group, has been remarked by all the geologists who have explored the 

 country. Dr. Leconte, considering the strata as Cretaceous, mentions 

 them in his report as continuing southward of the Raton, along the 

 base of the Rocky mountains, forming an immense terrace, which 

 extends as far south as the valley of the Tonejo, and perhaps even to 

 the north bank of the Cimarron. From this place northward to the 

 base of the Spanish Peak, these sandstone beds, always with the same 

 characters and superimposed upon the Fort Pierre Group, form an im- 

 mense terrace, perpendicularly cut, like a wall facing east, High ^bove 

 the plain. They support, the lignitic beds which still tower above 

 them, either ascending in steep declivities from the top of the perpen- 

 dicular sandstone, or receding at some distance, where they have been 

 more deeply sapped by erosion. This abrupt front, says Dr. Hayden, 

 seems to form a sort of shore-line of a wonderful basin, as if a body 

 of water had swept along and washed against the high bluffs, as along- 

 some large river. The stage-road from Trinidad to Pueblo follows 

 the base of these cliffs for thirt^^-two miles. South of Trinidad, the 

 lignitic measures have been followed nearlv without interruption to 

 the Maxwell estate, about fifty miles. The area which they cover, at 

 and around the Raton mountains, may be estimated at 600 to 800 

 square miles. The same formation is reported farther south, near and 

 around Santa Fe; in the Gallisteo valley; along the mountains to 

 Albuquerque, and in the valley of the Rio Grande, as far south as 

 Fort Craig. Ever Nowhere, with a single exception, these Lignitic 

 measures have exposed, by their relative position, by the absence of 

 animal remains in the thick beds of sandstone, which indicate their 

 base and constitute their foundation, by the homolog}^ of their marine 

 and land flora, as recognized in the remains of fossil-plants which 

 they contain in abundance, all the characters authorizing the separa- 

 tion of this group* from the Cretaceous formation. 



From Pueblo to Canon Cit}", fortj^-five miles, the stage-road follows 

 a broad vallej^ closed on the south side b^^ the Greenhorn mountains, 

 on the north side by the Rim Range of the Colorado mountains, over 

 which towers Pike's Peak, whose summit is visible all the time. The 

 whole valley is essentially Cretaceous; all tlie eminences, either near 

 the borders or in the middle, are hills of this formation, molded by the 

 erosions of the Arkansas river, which has du^- numerous beds in this 



