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Show • 304 pressions of long linear leaves and endogenous root- like bodies, together with small fucoidal markings. Higher in the bluffs, heavy ledges of buff and reddish sandstone appear, showing a slight inclination down the valley, or southeastward, indicating, in connection with the opposite dip observed at the head of the park, a gentle undulation in the strata, more or less parallel to the metamorphic ridges ten or fifteen miles to i the west. Looking up the valley from this point, we gain a beautiful view of tbe Vermejos, showing the peaks to the north of the great truncated pyramidal cone, framed in between the walls of the gateway. It is with peculiar emotions each re- appearance of their familiar domes is hailed; and so constantly have they attended our progress through the parks that it is with equal reluctance we now turn our backs in adios to these majestic mountains. Theuce the valley continues, closely pressed by the hills, a distance of two or three miles, when they suddenly diminish in altitude, and recede as we approach Cameron's, on the Elizabethtown and Trinidad road, where the stream enters a broad depression occupied by low upland undulations, which are clothed with pine and pinon and extensive grazingrange. This undulating belt probably marks the breaking- down or eastern limits of one of the terrace- levels of the Tertiary plateau, or a stage in the drainage of the Post- Tertiary basin, whose waters for a time swept the base of this low escarpment. Considerable tracts of bottom land, or low, shelving terrace- benches, continue from this point down the valley some nine miles to Mr. Stoat's, the border upland gradually increasing in elevation above the deepening bed of the stream, and drawing nearer ou approaching ( he great bend, where they present bold bluffs and escarpments, often madenp of immense beds of sandstone. Here the Yermejo nearly doubles upon itself in the distance of about one and a half miles, and in the course of ages it has excavated its channel deep into the Tertiary deposits, which rise in precipitous and frequently vertical walls to the height of several hundred feet above the shadows that dwell at their base, and which no ray of sunlight penetrates. A practicable bridle- trail traverses the canon, crossing and recrossing the impetuous stream, whose bed is blocked by immense masses of sandstone dislodged from the ledges above, and paved with bowlders, which afford treacherous footing for our animals, winding beneath overhanging ledges, now crossing a thicket- grown miniature iutervale, then rising high up on the shoulder of a steep talus of dSbris- a bit of journey performed with some degree of misgiving, but remembered with liveliest satisfaction. Below the great bend, a distance of four miles, the stream continues walled in its narrow valley by sandstone escarpments, when it sweeps round a low ledge and opens out below into the gradually- widening level intervale, which extends thence some three miles to the embouchure of the valley into the plains. Rounding the high point in the angle south of the valley, the road passes up through shallow depressions, past deep alcoves studded with picturesque castellated rocks and totteriug watch- tower pinnacles, oat upon the long pinon covered slope bordering the basin of the Canadian. The accompanying profiles are intended to exhibit the general structural features iu different parts of the region noticed in the foregoing pages, and the relative position of the various geological element* there met with. Fig. 1, plate 48, represents a profile extending easterly from Costilla Pass in the main range, across the narrow belt of overturned Palaeozoic and Mesozoic strata at the base of the mountains, out upon the Tertiary of the Baton plateau, crossing the head of the Canadian basin, tbe |