| OCR Text |
Show 66 ite; but little of the Rocky Mountain felsdpar- porphyry appearing. This annearance was confirmed by an examination of the spur bounding the valley on the s< uth. Mr. Sanchez showed me a tooth of the Mastodon ohioticus, which was found in the clay of the valley along the Rancho Creek. The axis of the Picnris Mountains, the western spur of the main range already mentioned, is gneiss rock, portions of which are filled with garnets and crystals of hornblende and tourmaline, and which incloses at some localities masses resembling a hard soaps tone. The sedimentary rocks rest upon its northern face at various dips, often 35° and 45°. I made a section by following the valley of the Rancho Creek, which cuts the strata at right angles for about eight miles. On entering the ravine, the first formation is a siliceous limestone, dipping northwest 35° ; beyoud, t. « ., below thisy appears a bright- red conglomerate, which greatly resembles the Triassic beds of other localities. It changes in long weathering to a dirty greenish color on exposed points. It is continued into a sandstone, which has a dip of 45° northeast, and a thickness of more than a thousand feet. They contain innumerable vegetable remains, mostly leaves of a reed- like form. This deposit is underlaid by the limestone of the Carboniferous period, which is at the top thin- bedded and alternating with dark- colored shales. I found here great numbers of characteristic fossils, weathered out and beautifully preserved ; including Echinodernis, Crinoids, small species of Orthoceras, Goniatites, Spiri/ er8, and other Brachiopoda, with Gastropods resembling Trochus, Turritella, and Xerita. About ten miles southeast of the point where the Raucho Creek issues from the mountaius, in a rugged ravine, is an outcrop of coal, which has been exposed by Mr. Sanchez. I visited the locality, and found a bed of coal of an inferior quality of 15 to 18 inches in thickness, dipping north 30°. The rather shaly strata above it are filled with Carboniferous fossils. Another bed of coal near the mouth of the canon of the Rancho is of still less value; thickness, 15 inches; dip, 45° north. The rocks of the Trias and Carboniferous form an open anticlinal ridge before finally rising to the axis of the Picuris Mountains. The ravines of the south side of the Picuris Mountains are filled with the arenaceous beds of the Santa Fe* marls, as already described by Dr. Hayden. The erosive forces, have cut deep valleys and gorges from their mass, leaving tremendous castellated and bastioned escarpments of a thousand feet elevation. Interesting views of these beds may be had by following the valley of the Embuda Creek, and the cafiadas which extend from it to the southward and eastward. After careful examination, I could only find a single fossil, namely, a penultimate phalange of a lateral digit of probably a three-toed horse. Crossing the Rio Grande by a ford not far from the mouth of the Embuda Creek, I climbed the rugged face of the lava mass that forms the sides of the cation of the river, and which underlies the region on its eastern side, and found myself at the base of the " Pliocene" sands, which there form bad- land hills of much elevation. Some of them are worn into castellated forms of much beauty ; one in particular reminding me of the Eocene Church Buttes of Wyoming. From their summits an extensive view was had of the triangular area inclosed on two sides by the Rio Grande and the Rio Chama> with the two drainage- areas of the Ojo Caliente and El Rito Creeks. Oa traversing this region, it was found to be entirely composed of the " Pliocene" sands, and to be-very and, with cedars scattered irregularly over the^ urface. The springs of Ojo Caliente number three, the most important issuing from a vertical ledge of gneiss, whioh is there traversed by a wide quartz- vein. The temperature of the warm springs is front 116c to 120°; they contain abundance of a confervoid alga. In the creek below I saw a cyprinoid fish ( Gilapandora, Cope) taken with the hook. Near to this point I first observed the blue partridge, ( Callipepla squamata, Vig.,) which is readily distinguished as it runs by the white under side of its erect top- knot. In descending the Rio Chama, the arenaceous bluffs are continually in view on the-north side, and occasionally display layers of basalt alternating with the sandstones. In this situation, the basalt is at times concretionary. The bed which bounds the Rio Grande on the west terminates at the junction of the Chama in a high point. On the southwest side of the Chama, a similar stratum gives the mesa form to the hills nearly to the mouth. South of these the Jemez Mountains rise in impressive proportions, and, extending southward, bound the Rio Grande Valley on the west. The wide valley between the Jemez and the Sangre de Cristo ranges is almost entirely filled with ' the Santa F6" marls. Their sandy character is not - favorable* to agriculture, being scarcely preferable to the basalt, so that cultivation is confined to the narrow valleys of the tributaries of the Rio Grande. The intervening country is either absolutely naked or covered with cedars. Occasionally, as near San Ildefonso and near San Felipe, a fragment of the lava remains, protecting the-nnderlying Pliocene beds, forming a fiat- topped butte, generally termed a Huerfano. The beds of the Santa F6 marls are alternately softer and harder sandstones and conglomerates, varying from white to greenish- gray and to light rufous. They dip generally 10° to 15° toward the east, and away from the basaltic mass of the Jemez range. They contain the remains of extinct Vertebrata, mostly Mammalia, which have enabled |
