OCR Text |
Show 200 No sedimentary rocks were observed in the Culebra range. Ore deposits are found at but one locality in this range, viz. one mile east of Culebra Peak. Mr. £. D. Bright, of Trinidad, Colo., who visited this locality informs me that there is a vein of quartz-bearing silver 7 feet wide running through hornblendic granite. The ore assays $ 75 a ton. Another locality 4 miles east of this point has been discovered where the ore yields 52 per cent, of copper and 6 ounces or silver to the ton. The granite forming the summit of the Culebra Peak contains a large amount of feldspar. The rock is traversed by numerous joints and fissures. It has also undergone much disintegration, and a large number of detached fragments is the result. Jasj er is found in small quantities on top of Culebra Peak. There are three peaks south of Culebra that probably consist of granite, but I did not visit them. The rock in these peaks is colored red by oxidation of the iron. The range then trends southwest, and low ridges of sandstone appear for 15 miles south to Costilla Peak. The ridges slant gradually in going south. They are formed of a fine- grained yellowish sandstone that sometimes passes into a coarse conglomerate. No fossils were found in this rock. The sandstone shows mud- cracks and rill- marks, thus proving that it was formed in shallow water. The lofty peaks were islands in the primeval sea while the sandstone was formed. There are also on the eastern side of the Culebra range perpendicular walls of ferruginous sandstone. One of these walls at Beaver pond is of a brilliant red color, reminding one of the rock in the Garden of the Gods. The Cimarron range contains a greater variety of rocks than the Culebra range. Beginning in the north with Costilla Peak, whioh slopes very abruptly on the northern side, we have diorite containing much olivine. Massive quartz is found on tjjie top of Costilla Peak, and small bowlders of granite occur on its slopes. On the western side of the [ Cimarron ( range the granite assumes the columnar form, reminding one of the words of the poet: " The wild rocks shaped as they had turrets been, In mockery of man's art. On the east side of Comanche Creek a variety of pinkish trachyte occurs in the forms of curved, long prismatic columns, resembling the basaltic columns in the island of Staffa. Directly east of Costilla Peak is a short ridge of light- gray quartzite running parallel to the Cimarron range. The ridge is about 400 feet high. It is traversed by many fissures, and the rock is very much weathered. A small stream has cut its way through the ridge, thus forming a gap. On the west side of the ridge a bed of lbnon-ite outcrops. The rock is hard and fine grained, but breaks easily into thin fragments upon being struck with the hammer. Proceeding south from Costilla Peak the rock is for the most part granite. Both red and gray varieties of granite occur, as well as coarse- grained granulite. On the western side of the Cimarron range feldspar- porphyry occurs, having a dark- gray matrix with white crystals. At the head of Moreno Creek the granite is poor in mica. Elizabeth Baldy Peak, the highest mountain in the Cimarron range except Costilla, is composed of fine- grained gray granite. A mass of dark- gray mica- schist outcrops on the western side of this mountain. Just north of Elizabethtown a mass of gray feldspar- porphyry outcrops. The town itself rests on granite, while blue limestone outcrops but a mile below it. In this blue limestone two species of inoceramus were found, which Dr. White informs me belong to the Cretaceous age. The occurrence of fossilifer-ous limestone in the Moreno Valley, between the Cimarron and Taos ranges, is in all respects singular. I was unable to define the limits of the limestone. Six miles below Elizabethtown a vein of bluish granite outcrops at the head of Cimarron River. From this point the range consists of reddish granite and granulite as far as Uraca Peak on the south. In the vicinity of Uraca Peak igneous rocks, such as trachyte and vesicular basalt, occur. Bluish hornblende schist is found on the south side of Uraca Mountain. Gray trachyte occurs along the banks of Uraca Creek, and south of this are mesas of basalt extending beyond toe foot- hills into the plain. The cavities in the basalt are sometimes filled with white calcite. The western side of the Cimarron range is much steeper than the eastern side. A series of broad foot- hills, composed of sandstone, horizontally stratified, runs along the eastern side of the range. Much erosion has taken place in these foot- hills. They are covered with a net- work of cations. In the Van Bremmer Park there is a detached mass of yellow sandstone, about 100 feet high, standing alone in the plain and at least a mile from the nearest foot- hill. This was the most striking example of erosion noticed. Considerable lignite and a few veins of coal are found in the foot- hills east of the Cimarron range. The Taos range consist chiefly of granite and feldspar- porphyry, but many other rocks occur also. Taos Peak, the highest point in the range, ( 13,143 feet high,) is composed of gray granite and syenite, capped by mica- slate. This is the only locality of mica- slate between La Veta Pass and the Santa Fe* range. A fine section of the Taos range is seen in passing through the canon of the Colorado Creek. In entering the canon at the Placita de San Antonio and traveling eastward |