OCR Text |
Show 287 only its lower measures, or about half its actual thickness, which probably reaches 1,000 feet in this district. Looking northward, the same formation and conformation prevail, and out of which seem to rise the Spanish Peaks, the Purgatory intervening, but bidden in its valley 2,000 feet below. To the east, the view is arrested in the foreground by the wild intricacy of ravines scoring the Tertiary deposits, above which rears the massive wall of basalt which stretches far to the east and southeast, constituting a blank horizon from its initial extremity in the embattled heights of Fisher's Peak, which frown down upon the valley of the Purgatory. This great table- land, the Chicorica Mesa, attains an elevation quite equal to the general altitude of the Eaton Hills. The somber outlier known as Fisher's Peak may even exceed this altitude; but it plainly sinks away to the southeast and east, and beyond the Trinchera it is no more than 7,000 feet above the sea. Its sides in the southern declivity are gashed by deep ravines, with intervening grassy, terrace- like slopes, underlaid by the Tertiary deposits and strewn with the rough angular fragments fallen from the dark basaltic wall above, which is rarely broken down sufficient to allow easy access to its herbage- clothed summit It is impossible to examine this great basaltic- capped mesa without being forcibly impressed with the probable important influence it has* exerted not only in the origin but preservation of the Raton divide and the Tertiary plateau. Thus, it will be seen that the Baton Hills in their entire extent are composed of the great Lignitic formation, which abuts upon the ineta-morphic deposits which flank the main range, probably concealing them from view at the point of impingement in the vicinity of the Francisco Pass. It is along the crest of this divide that these Tertiary deposits also probably maiutain their greatest development, and where they may reach a thickness considerably in excess of that just attributed to the formation. When the great escarpment- exposure is examined from the plains at a distance sufficient to afford a comprehensive view of several miles extent, there is observed a marked diminution in the relative vertical in extent of the formation in its extension southward, which, however, does not appear to be a thinning in that directiou of the sediments composing its distinct strata, but rather the absence of successive superincumbent beds which have been removed by denudation. This phenomenon is perhaps nowhere more markedly apparent than in comparing the relative elevations of the buttressed heights, which mark the embouchures, like headlands along the coast, of the Canadian, Vermejo, and the Cimarron; and, to obviate the possibility of misconception, the eye can trace the continuity of certain marked horizons in this magnificent outcrop a distance of thirty miles. The difference in the relative level of the base of the formation at the respective exposures on the Cimarron and the Purgatory would appear to-indicate a gentle northeasterly inclination of the strata along the line of this outcrop, amounting perhaps to 700 feet between the above points, or in a distance of about fifty miles. But to the unassisted vision there is no perceptible dip, while the apparent inclination is probably due to the line of outcrop extending obliquely to the descent of the strata from the flanks of the mountains to the west, and possibly also in part attributable to the gentle uplift parallel with the Urac Mountain along the southern borders of the coal- field. It would appear most probable that these deposits have also participated to a greater or less extent in the uplift along the western borders of the field, though it is hardly more certainly apparent than the northerly inclination above alluded to unt* 1 |