TO JUNCTION OF GRAND AM) GREEN KIVERS. 5] 



appear in the vicinity of Santa I'Y, they require. to be mentioned only as constituting 

 the group which 1 have denominated Upper Cretaceous in tin- present report, and to 

 distinguish them from the "Upper Cretaceous" of a former one, which I am compelled 

 to regard as the middle portion of the series. 



The Cretaceous formation, then, as exhibited in the vicinity of Santa IY, consists 

 oi the two -roups to which I have referred in the preceding pages as Lower and Mid- 

 dle, on a former occasion as Lower and Upper Cretaceous. Of these the first con- 

 sists, as elsewhere in New Mexico, mainly of coarse yellow sandstones with impres- 

 sions ol angiosperm dicotyledonous leaves; the second, of calcareous shales and 

 ferruginous, shaly, sandy limestones, with numerous marine fossils, such as Amnion ids. 

 Nautilus, Inoceramus, Gryphma, fish-teeth, eve. Of these two groups the lower caps the 

 chll's borderingthe valley oi' the Pecos on the south, forming the floor of the greal plateau 

 winch stretches away southeast, where it becomes the Llano Estacado. It is not yel 

 demonstrated that all the yellow standstone formation of this plateau belongs to the< Ireta- 

 ceons formation, and that it is not in part, as claimed by M. Marcou, of Jurassic age. 1 

 should say, however, that in the vicinity of Santa l'Y 1 was able to discover no Jurassic 

 fossils : but, on the contrary, near Galisteo, in the yellow sandstone specifically noticed 

 by .M. Marcou, and regarded by him as Jurassic and identical with that of the Llano, I 

 found impressions of dicotyledonous leaves, which prove it to he ( Iretaceous. In the vicin- 

 ity oi the mountains the stratification is considerably disturbed, and in many localities 



the ( IretaceOUS rocks are broken through or removed hv erosion : hut, with local excep- 

 tions, they constitute the surface formation in all the area examined by our party east of 

 the Sandia and Placer .Mountains, and south and east of the mountains of Santa I'Y. 



The valley of Galisteo Creek has cut through the Middle and Lower Cretaceous 

 rocks, and has freely exposed the Red l>eds below. Going from the base of the ( Vr- 

 rillos to Gralisteo ('reek, alter passing the eruptive material which composes this group 

 of hills, the Middle Cretaceous shales are seen occupying a belt a mile or more in 



width on the north side of the stream. Beneath them are the yellow Cretaceous sand- 

 stones, underlying which are the blood-red sandstones and shales of the Trias. On 



the south side oi the creek, ascending toward the base of the Placer Mountains, this 

 section is again encountered. The Middle Cretaceous shales here contain beds of li<>- 

 nite several feet in thickness: at one point, bv an eruption and overflow of trap, this 

 lignite has been metamorphosed and converted into a compact and brilliant 

 anthracite. 



The boring made by Captain Lope, I'. S. A., near Galisteo, in the hope of obtain- 

 ing water that should spontaneously rise above the surface, was nearly all done in the 

 Middle Cretaceous shales, which here have a thickness of at least thirteen hundred 

 feet. The work was commenced in Tertiary tufaceous limestone precisely like thai 

 so frequently mentioned in Chapter I. After passing through twenty-five feet of this 

 material the shales were struck, and they had not been passed through at the time the 

 work was abandoned It is to be regretted that the experiment had not been carried 

 somewhat further, as it is highly probable that the Lower ( Yetaceoiis sandstones would 

 soon have been reached, and, dipping down as they do from the Placer Mountains, it 

 is at least possible that the water flowing through them would rise 1o the surface. A 



