GEOLOGICAL SURVEY OF THE TEREITOEIES. 169 



CHAPTER VII. 



FROM SANTA Ffi TO TAOS. 



On the western flank of tlie Santa Fe Mountains, near Santa Fe, I 

 found the foot-hills, which are exposed by the wearing away of the marls, 

 to be composed of carboniferous beds. These beds of limestone rest 

 directly on the granite, and are associated with gray and reddish shales 

 and some beds of sandstone, the whole dipping west at an a,ng]e of 

 thirty-five to forty-fi v^e degrees. The limestones were charged with fossils, 

 as many and as well joreserved as I have seen them at any locality east 

 or west. In many places these beds of limestone are carried high up 

 on the granite hills; sometimes dipping toward the mountains as if a 

 portion of an anticlinal. The metamorphic rocks are gneissoid at first 

 on the flanks, but gradually become massive granites toward the main 

 axis of the range. In a small creek, which leads down from the mount- 

 ains, I saw immense masses of granite breccia, mostly angular fragments 

 of gneiss or red feldspar, with some rounded masses cemented with a 

 granite i)aste. The limestones about Santa Fe are converted into excel- 

 lent lime. The foundations of the jail and court-house are made of it. 

 The fossils are very numerous, both in individuals and species. Dr. 

 Newberry has given a list of them. I found several species of Fro- 

 dtictus, Sprifera suhtilita, and many others. These limestones do not 

 seem to extend far along the sides of the mountains. From Santa Fe to 

 Embudo Creek, and mostly even to Taos, the Santa Fe marls cover the 

 country. On the east side of the Elo Grande I did not observe a single 

 dike, from the Ceriilos to the mouth of the Chama Creek. North of that 

 the melted material has been poured over the marl so as to form broad 

 mesas. On the west side there are numerous outbursts of igneous mat- 

 ter. These Santa Fe marls reach a great thickness north of Santa Fe, 

 in the E,io Grande Valley, from one thousand two hundred to one thou- 

 sand five hundred feet, and have a tendency to weather into similar mon 

 umental and castellated forms, as in the "Bad Lands." The upper por- 

 tions are yellow and cream colored sandstones, sands, and marls. Lower 

 down are some gray coarse sand beds with layers of sandstone. All these 

 marls dip from the range westward three to five degrees. The Eio Grande 

 wears its way through these marls with a bottom about two miles wide. 

 On the west side are distinct terraces with the summits planed off smoothly 

 like mesas. The first one is eighty feet above the river; the second one, 

 two hundred feet. These marls extend all the way between the margins 

 of the Santa Fe Mountains on the east side and the Jemez Range on 

 the west. Most of the Chama Hills, and I think the entire hills, are 

 composed of it. At the junction of the Chama Creek with the Rio 

 Grande, a point comes down between the two rivers which is covered 

 with basalt. This continues into the San Luis Valley nearly to Fort 

 Garland. Near the mountains the hills are covered extensively with drift, 

 and sometimes they are composed largely of boulders and marl or 

 sand. The country is full of the dry beds of creeks or cirroyas, as 

 they are called. All these carve their valleys out of these marl beds. 

 As we go northward near the mountains, the rounded boulders become 

 more and more numerous, but near the Eio Grande, where fchey have 

 all disappeared, the source of this great thickness of sediment is apparent. 



The Ojo Sarca Creek rises in the Sante Fe Mountains and flows into 

 the Eio Grande, forming a valley which is remarkable for its ruggeduess. 

 The marl beds are nearly horizontal and the harder layers of sand pro- 

 ject out of the sides of the bluft" hills like steps for four hundred to six 



