307 



base of the cone is coarsely vesicular and of a dark-brownish color, en- 

 tirely dissimilar in a])pearance from the basaltin the neighboring mesas, 

 which latter varies Irom reddish to dark brown, specked with light 

 gray, and homogeneous in texture. To the eastward, the low, uneven 

 platform drops down into the depression between the Capulin and Sierra 

 Grande, in which is gathered the drainage of the headwaters of the dry 

 Cimarron. 



The lines of low basalt-capped bluffs on the west and northwest 

 borders of the vega present at least two distinct benches, of which the 

 lowest is about 75 feet in height, the other or highest (that shown on 

 the left of the Capulin in the sketch) perhaps as high again above the 

 vega. The lower one presents along its crest frequent abrupt outcrops, 

 but in the higher bench the basalt forms a low uninterrupted wall, 

 showing very irregular columnar structure, below which the debris- 

 strewn talus descends to the lower levels. There is also here observed 

 a lower basaltic outcrop, which forms a third irregular bench, some- 

 what less than half the height of the next higher bench ; but whether 

 it represents a distinct deposit, independent of those appearing in the 

 higher terraces, was not determined. Indeed, the thickness of the 

 basaltic beds was in no place satisfactorily exhibited, though in places 

 the upper oue shows a solid outcrop of 20 to 30 feet without revealing 

 the nature of the deposits upon which it rests. 



]Sfearly due north of the Vega Spring, overlooking the intervening 

 basaltic beds above alluded to, another volcanic cone rises to view, 

 which, though not so perfect as the Capulin, is yet unmistakable in its 

 origin ; the western rim is deeply broken down, showing the crater- 

 depression, while the opposite wall still remains perfect, and is much like 

 that of the Capulin. Perhaps not quite as high as the latter cone, it 

 rests upon a similar uneven upland eminence, and is grassed over to the 

 summit. The formation of these high spreading bases seems to be 

 directly attributable to the volcanoes themselves, and may have been 

 built up in the early stages of the eruption, which terminated in the 

 building-up of the conical elevations around their orifices. 



The Sierra Grande, like Laughlin's Peak, when seen from the v/est, 

 presents a broad-based mass gradually culminating in a blunt or rounded 

 summit, which attains an altitude of about 8,000 feet. Laughlin's Peak, 

 however, viewed from the northwestward, shows a deep depression 

 extending half-way from the summit to its broad base, and which has 

 all the appearances of a crater, the northwestern rim of which has been 

 demolished. The contour of both these mountains, as also that of the 

 ^Eagletail, suggests their possible origin as centers of volcanic eruption; 

 but they probably mark the sites of much larger and possibly older 

 craters than the Capulin anil others, which still retain their symmetrical 

 form and undoubted character. Their conical shape would seem to in- 

 dicate a different origin from that of the basaltic overflows, which dis- 

 tinction, in the case of the Capulin, is also quite manifest in the difference 

 in the physical character of the igneous products ejected, and out of 

 which the cone surrounding its crater was built up. 



There would appear to be several distinct basaltic deposits in this 

 region, as evidenced by the presence of at least three or four benches, or 

 terraces, of different levels. As stated above, there are at least two 

 such deposits, occupying comparatively low elevations, bordering the 

 Capulin Vega; and probably a third and lowest bench, which latter, 

 from the character of the material thrown out from the excavations of 

 some burrowing animal (perhaps the prairie-dog) in the edge of the 

 vega, apparently rests upon light, indurated, marly shales, probably 



