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Show 306 ish sandstone, which often forms picturesque castellated masses, in which the elements have wrought miniature caverns, and which are covered with cedar, pinou, and low pines. The shales are undoubtedly of Cretaceous age, and it would appear equally probable that the overlying sandstone prove to be the base of the Tertiary formation. A few miles farther on, and perhaps twenty miles from the crossing of the Canadian, Hole in- Rock is reached, a little pool at the foot of alow ledge of very tough, grayish, phouolitic rock, which seems to be a dike pushed up through the sedimentary strata, along an east- west line, and which here crosses the head of a little branch of the Tanaja. From this point, the road passes over a sort of low divide, and yet within the depression, which is here bordered by similar topographic and stratigraphic features observed on the upper course of Tanaja Creek. In the course of a few miles, a more opeu country is reached; to the left or northwest, lowish basaltic- capped mesas, in which a branch of the Una deGato rises, and in the opposite direction the huge eruptive pile culminating in Laughlin's Peak. The latter mountain rises from a broad, undulating, grassy swell in the plain, and in which Mr. Kingman reports the occurrence of sandstone similar to that appearit\ g in the bluffs bordering the old valley- depression, which lies to the uorth-west. A gentle descent amidst surroundings which every step become more emphatically marked by the evidences of igneous phenomena which here abound, and in' a distance of fifteen miles from Hole- in- Rock, we gain the Capulin Vega, and camp beside a little pool which oozes from the swelling, peaty soil in the midst of the plain. The Capulin Vega is quite au extensive shallow basin, surrounded by gentle acclivities, low basaltic terraces, and isolated mouutains whose summits rise above the plain 1,500 to 1,800 feet, or about 8,000 feet above the sea. Its surface is quite level, with here and there shallow ponds; the mud of their slopiug shores whitened by an efflorescence which renders the water brackish at this season, and their margins unrelieved by a solitary tree. In the low places flooded by the rains, considerable tracts of coarse herbage, suitable for hay, occur; the drier portions of the vega possess a loamy soil, which is largely made up of the ^ a id derived from the degradation of the surroundiug igneous rocks. To the southwest, the surface gradually ascends into the upland at the base of Laughlin's Peak; and, on the northwest, the basin is hemmed in by low basaltic escarpments. To the east, the prairie rises into what appear to be broken- down volcanic cones, and beyond lies the broad-spreading mass of the Sierra Grande, to the right of which, and much nearer, a nearly perfect crater cone appears- the latter some eight miles and the former fifteen miles distant- which are destitute of trees, and grassed over to their summits with a tough reddish wire grass, which gives a delicate pleasing tint Ibo their smooth sides. But the most interesting feature of the environments is the Capulin Mountain, a perfectly symmetrical cone, rising from a broad low basis of scoriaceous rock to the height of near 1,800 feet above the vega. The summit is truncated, and occupied by a funnel- shaped crater between 200 and 300 feet in depth, and which is said to be grassed over to its bottom; on the southwest, the rim is slightly broken down, revealing ( he character of the crater to best advantage. The outer wall on the east side, as seen from the vega, presents an abrupt escarpment perhaps 50 feet in height; otherwise, the slope is very uniform, and covered with herbage and a growth of shrubs or dwarf- pines. The appearance of the mountain as seeti from the vega, to the southwest, is shown in the middle section of the foregoing sketch. The eruptive material occurring at the |
