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Show 87 seen. The southward route passes over the divide which separates tbe drainage of the Gallinas from that of the Paerco. South of this divide the Cretaceous beds, including their highest members, Nos. 3 and 4, disappear on the sides of the Nacimiento Mountain. The mountain itself is the feldspathic porphyry of the true Rocky Range axis, which, rising through the Mesozoic beds which cap the northern part of the Sierra Madre forms* its most elevated portion. At the village of Nacimiento, the red Triassio beds are visible on the mountain- side, and its upper sandstone dips south as well as west from an elevated position. The range extends south from this point as far as my observation reached. The valley is occupied in localities near the mountains with the red feldspathic gravel usual along the Rocky Ranges. Some of the Mexicans, spoke of copper- mines, with ancient stone buildings, in the ravines of the Nacimiento. I conclude this chapter by a little further allusion to the Cretaceous hog- back, of which the most important is that formed by No. 3. At oue of the depressions in this line ( Fig. 11,) the erosion has displayed a considerable bed of lignite. It appears in four beds, which are represented in the following section: Pio. 11.- Synclinal in Cretaceous No. 3, opposite the Cafioncito de las Yogas. - Sandstone. - Shale, 10 foot. - Lignite, 10 feet. - Sandstone. - Lignite, 3 feet. - Sandstone. - Lignite, 3 feet. - Sandstone. - Lignite, 4 feet. FIG: 12.- Section of Cretaceous No. 3 at locality of Fig. 11. Feet Sandstone No. 3 00 Limonite 24- Carbonaceous shale 10 Lignite 10 Sandstone 00 Lignite • 3 Sandstone 00 Lignite 3 Sandstone... #- \ 00 Lignite 3 Total 80 This lignite bed extends throughout the region west of the Rocky Mountains wherever No. 3 occurs, and is the bed which has been mistaken for the true lignite, or No. |