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Show 76 The Mammalia of the Santa Fe" marls above described fall into the following orders: Species. Carnivora 4 Artiodactyla 9 Perissodactyla 5 Proboscidia 1 Rodentia 3 Aves 3 Testudinata 2 Undetermined 2 29 CHAPTER IV. • TIIE VAUJCY OP THE RIO GRANDE FROM SANTA FE TO THE ZANDIA MOUNTAINS. The country composed of the Santa Fe" marls consists of bad- land tracts alternating with sage- brush plains. Near Santa F6} the surface is worn into rounded hills. The level tracts are intersected by deep arroyos, ( drainage- ravines;) and the bad- land tracts present the usual features of precipitous bluffs and buttes penetrated by cafions, or of low hills and naked terraces. A short distance south of San Ildefonso, the Rio Grande again enters a cafion, which is caused by the presence of a horizontal bed of basalt covering the underlying Tertiary beds and protecting them from erosion. This cafion terminates the open valley which commences on the east side of the river some distance above the mouth of the Rio Chamra, and which has become the seat of a considerable population, in spite of the unfavorable character of its soil. Here are situated the Mexican towns of Play a Alcalde, Chalma, Santa Cruz, and Santa Fe*, and the Pueblo Indian towns of San Juan, Santa Clara, Pojuaque, Coyamanque, nambe, San Ildefonso, and Tesuque. Through the attention of General Gregg, commanding the District of New Mexico, I was furnished with means of transportatian southward as far as the Zandia Mountains. The country south of Santa F6 is level, the road passing over the basaltic plateau above described, which prevents exposure of the Tertiary beds. The surface is covered with sage, { Arteme* ia,) with other plants, a little grass, and two or three species of cacti, one of which is a subcylindric Opuntia, with broad white spines forming flat rosettes. Descending into the valley of Galisteo Creek, which enters the Rio Grande thirty miles below San Ildefonso, the road passes over the upturned edges of the beds of the Cretaceous formation. They present escarpments toward the Rio Grande, dipping east and a little north 20°. The upper beds are of a yellow mud- color, and contain much cone- in- cone and some badly- preserved shells. The mud- beds include some strata of black carbonaceous shales, and the whole probably belongs to the Cretaceous No. 4. Below these, nearer to the creek, a series of harder slaty strata, including many Inocerami, appear, and these in turn are underlaid by about 300 feet or more of soft buff sandstones, which include occasional strata of carbonaceous slates. These form precipitous hills or bluffs along the course of the creek, and belong probably to No. 3. The thickness of the beds of Nos. 3 and 4, where crossed by the road, is about 500 feet. Below the buff sandstones, and apparently conformable with them, is a series of red sandstones of about 300 feet in thickness. I could find no fossils in them, and am uncertain as to their exact age. They form the Galisteo sandstone of Hay den, who regards them as peculiar to this region. These beds are further described below. Opposite the mouth of the Galisteo, the bad lands of the Tertiary again appear, but are composed entirely of coarse gravel. The narrow valley of the Tuerto Creek, which enters the Rio Grande ten miles south, is bounded by similar hills of gravel, sometimes very coarse, resembling cobble- Btones, and the same formation ap]> ears in hills between the town of Algodones and the Zandia Mountains. At San Felipe, the basalt bed disappears again from the eastern side of the Rio Grande, but caps the high bluffs on the western side. Beyond these, to the southwest of Algodones, red bad- land tracts are visible, which probably form a continuation of the Santa Fe" marls. A section carried across from the Rio Grande, at Algodones, to the Zandia Mountains, through the village and creek of Placita, gave the following results: The road winds among, and ascends for several miles, the mesas of coarse Tertiary gravel and cobble- stones until it reaches a wide plateau, from which the mountains rise ou the east. This tract is traversed by Placita Creek and its tributary arroyos, which furnish interesting sections. From these it appears that the greater part of the plateau consists of the yellow muddy shales and sandstones of Cretaceous Nos. 4 and 3. They form the bottoms, and in some cases the walls of the arroyos, and rise in low mono-clinal bills at various points on the plateau. The beds dip northwest 20° to 40°. In the intervals between the hills there is a deposit of indurated clay of 40 feet in thickness of post- Pliocene age. I obtained teeth and other bones of Elephas primigenius, sub- |