| OCR Text |
Show 104 the Triassic northeast of Bacon Springs, and the Carboniferous near Fort Wingate, in a natural, undisturbed positiou. But in the Naciniiento range it is different,- the Carboniferous strata occupying tbe very crest of the mountains several thousand feet above the Cretaceous formation, leaving no room to doubt that this range is the product of an upheaving which occurred toward the close of the Carboniferous epoch. A section of this region is presented in Pig. 2. The predominating rock of the Cretaceous mesas of Naciniiento Desert is sandstone, while liniestonej of such frequent occurrence in the Cretaceous deposits of the Arkansas Valley, is here remarkably rare. Slate, clays, and brown coal form here* and there subordinate strata of tbe sandstone. In the slate are found impressions of leaves as well as an occasional Inoce-ramu*. The brown coal contains a yellow brittle resin, which on examination proved to be new to science, and was described in vol. Ill of the Survey Reports, under the name " Wheeler ite." Fibrous gyp& um of silky luster accompanies the brown coal; also limonite occasionally. In a number of mesas along the Rito Torre-ones, the brown- coal strata have been destroyed by tire, at least the exterior portion of the seams, the ashes still being there. The overlying clay strata were entirely metamorphosed by the heat and turned into brick, having a blood- red color, and giving out a ringing sound. The underlying ferruginous and calcareous shales were turned into a vesicular slag. I observed a similar state of things in analogous strata in the Moqui country. In regard to tbe succession of the strata, I took quite a number of sections. At the Rio Puerco the following order appeared: Feet Top light- colored sandstone 4 Slate clay 0.5 Brown saudstone 0.75 Slate 0.30 Brown coal 2 Base slate 6.2 In ouo mesa hording tbe Rito Torreones the strata were exposed in the following order of succession : Feet. Top yellow sandstone 20 Brown coal 0.5 Slate 4.75 Brown saudstone *-.. 5 Gypsum deposits of considerable thickness occur east of the Rio Puerco in several places. Between Ojo del Espiritu Santo and the Rio Puerco tbe mesas show a dip of 20° to 25c, while the strata elsewhere show no disturbance J ~ or displacement from a horizontal position. | c Here and there we meet with granite hills in '£ the northeastern portion of the Naciniiento J Desert, forming a striking contrast to the'eur- P rounding mesas. These hills were formerly £ cliffs in the Cretaceous ocean. g Proceeding from the Rito Torreones toward J ^ Mount Taylor, we pass a valley snrronnded by 1 < yi most picturesque sandstone forms, resembling 0- castles, towers, and monuments, all the result of £ erosive agencies. A little farther south the vol- |
