92 EXPLORING EXPEDITION FEOM SANTA FE 



the Gypsum formation, usually so entirely barren of fossils, would here well repay 

 labor spent in its examination; and it is greatly to be desired that future explorers of 

 this far-off region will make an earnest effort to obtain what is, perhaps, here alone 

 obtainable, the means of settling the vexed question of the parallelism of the Gypsum 

 formation with deposits whose age has been accurately determined elsewhere. 



In the same stratum with the Saurian bones I discovered the only fossil shells I 

 have ever seen from that group of rocks in New Mexico. These have the form of Natica, 

 but are probably not susceptible of accurate classification. 



Three miles below our "Saurian camp" (26), we reached the mouth of the Canon 

 Pintado, which here opens out on to the second step of the table-lands in the descent to 

 the Colorado. The surface-rock of this plateau is everywhere the soft, massive, cal- 

 careous sandstone or indurated marl which forms the base of the section in Canon 

 Pintado. It is a comparatively soft rock, and contains a great deal of gypsum, very 

 uniformly disseminated. It lies in thick beds, scarcely separated by any distinct part- 

 ings, and yet exhibits the most striking examples of oblique stratification which have 

 ever come under my observation; the inclined layers, which compose some of the beds, 

 forming an angle of 30 and 40 with the primary planes of stratification, which are 

 horizontal. The slopes of the inclined layers are often or 60 feet in length, with a 

 rise of 20 or 30, showing that they were deposited from water, at times very much 

 agitated. The colors of this rock are always very decided, but, in the same stratum, 

 or on the same horizon, they are exceedingly local; a lemon or orange yellow being 

 succeeded quite abruptly by rose-red, and this again by white. The prevailing shade 

 is, however, a red, deep blood-red, or some lighter tint, such as brick-red, rose- tint, or 

 flesh-color. It is a rather remarkable fact, that with such inclined and contorted layers 

 of deposition this rock should include so little coarse material, and it is impossible to 

 resist the conclusion that it is far more a chemical than mechanical precipitate, and 

 that the period of its deposition was the commencement of a great epoch, during which 

 peculiar physical conditions prevailed over not only the greater part of our continent, 

 but of the world, so peculiar and so widespread that we may almost call them cosmical. 



Everywhere over the second plateau are scattered buttes and pinnacles, wrought, 

 from the massive calcareous sandstone and the overlying Saurian beds, by the erosion 

 which has swept from this surface all traces but these of the immense mass of sedi- 

 mentary rocks wliich once covered it. Of these one of the most striking seen from 

 our route is the Casa Colorado, represented on Plate VI. It is a detached butte, some 

 300 feet in height, composed of red sandstone covered with the harder layers of the 

 Saurian beds. Another symmetrical and beautiful dome, composed of the same mate- 

 rials, is lemon-yellow, with a base of red. 



Our camps 27 and 28 were on what I have called the second plateau. Of these the 

 first was at La Tenejal, a deep excavation in the red sandstone, which retains so large 

 a quantity of surface-water, and for so long a time, as to become an important water- 

 ing-place on the Spanish trail. These natural reservoirs are frequently met with in 

 this region, and during the dry season are of vital importance not only to such travelers 

 as may be passing through it, but also to the small number of animals which here 

 make their home. It is not at all uncommon to meet with them even on the summits 



