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ish sandstone, which often forms picturesque castellated masses, in 

 which the elements have wrought miniature caverns, and which are 

 covered with cedar, piiion, and low pines. The shales are undoubtedly 

 of Cretaceous age, and it would appear equally probable that the over- 

 lying 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-Eock is reached, a little pool at the foot of a low 

 ledge of very tough, grayish, phonolitic 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 open 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 eruptiv^e 

 pile culminating in Laughlin's Peak. The latter mountain rises from a 

 broad, undulating, grassy swell in the plain, and in which Mr. King- 

 man reports the occurrence of sandstone similar to that appearing in 

 the bluffs bordering the old valley-depression, which lies to the north- 

 • 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- 

 Eock, 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 an extensive shallow basin, surrounded by 

 gentle acclivities, low basaltic terraces, and isolated mountains whose 

 summits rise above the i^lain 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 5 the mud of their sloping 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 sa id. derived from the degradation of the surrounding 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 b^' 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 to their smooth sides. But the most 

 interesting feature of the environments is the Capulin Mountain, a 

 l^erfectly 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 the 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 mount- 

 ain as seen from the vega, to the southwest, is shown in the middle 

 section of the foregoing sketch. The eruptive material occurring at the 



