GEOLOGICAL PAPERS. 149 



large areas of coniferous trees ; but, very differently from the present, 

 they were also spotted with extensive swamps for conserving the dead 

 generations of their arborescent giants, or it may be pigmies. 



Eocene deposits are found both east and west of the Sangre de 

 Cristo, and probably exist in other parts of the territory. West and 

 north of the Gallinas mountains is a mauvais terres, rivaling in as- 

 pect the similar region of Wyoming, Dakota, and Nebraska. Silici- 

 fied tree trunks, some several feet in diameter, are abundant. Many 

 reptile and some mammal remains have been removed from its marl 

 beds The marl beds are bordered by sandstone of the same age and 

 interstratified with it. This region was the site of a large fresh-water 

 lake in Eocene times, and its sediments aggregate 1000 feet in thick- 

 ness. The marl when wet becomes very slimy, and the wash from it 

 adds greatly to the turbidity of the Rio Grande waters. 



The Middle and Late Tertiary are represented in the Rio Grande 

 valley extensively. It was during this period that it was the bed of a 

 lake, or a series of linear lakes, extending for hundreds of miles, and 

 probably due to lava flows. The Llano Estacado upper strata are 

 considered of this age for 100 feet in depth, perhaps more. The re- 

 mains of an immense dog, as large as a bear, the three-toed horse, the 

 mastodon, the rhinoceros and the camel have been taken from the 

 marls. 



During the Glacial period New Mexico doubtless received cataclys- 

 mic rains with great frequency, and her canyons and mountain slopes 

 were deeply eroded by rock fragments, carried with torrential force 

 against granitic and basaltic ramparts, while Pluto and Vulcan joined 

 forces to flood with fiery streams her watercourses and to plaster 

 some of her valleys and park like plateaus with a coat of nether- 

 world cement. It was probably in this age that the Rio Grande 

 freed its channel from the natural bars of the Pliocene eruptions. 



In conclusion, it may be said the succession of formations in New 

 Mexico and Kansas are not very different, except as regards the 

 Coal Measures, but the physical features of surface are widely in con- 

 trast. 



