deposits enclose the remains of a fauna entirely dis 



: from that 

 •a r of the Loup Fork period and of 

 | «* more modern character. They 

 Jj are known as the Equus beds. 

 ••> J! This fauna was probably contem- 

 | £ poraneous with that which roamed 

 *£ through the forests of the eastern 

 £| portion of the continent, whose 

 |T. remains are inclosed in the depos- 

 . B its of the caves excavated from 

 S Jj the ancient limestones. 

 p. g - A more detailed account of the 

 g o formations is now given, with the 

 | | names of a few of the character- 



THE PUERCO. 



Tbi 





fur- 



| S sils, is known to belong to the 

 a £ Tertiary rather than the Post-cre- 

 j: ~° taceous series. It is regarded by 

 $t Dr. Endlich as a subdivision of 

 | g the Wasatch, but the characteris- 

 es .2 tics of its fauna are so marked as 

 * $ to constitute it a distinct horizon. 

 | a The most southern locality at 

 | g which it has been observed, the 

 1 * one from which I named it, and 

 g"J where its characters are distinctly 

 §| displayed, is west of the Jemez 

 „ ^ and Nacimiento mountains, in 

 Z - New Mexico, at the sources of the 

 £ § Puerco river. At this place its 

 * « outcrop is about 500 feet in thick- 

 's I ness, and has an extent of several 

 &'3 miles on both sides of the river. 

 !i § From this point the strike is 

 « I northward, keeping at the distance 

 _5 * g of a few miles to the eastward of 

 escarpment of the Wasatch formation. It contracts in depth to 



