After dinner we moved on, ascending the creek above mentioned, whose valley was sufficiently wide for a little distance, to afford us an easy and unobstructed passage. The stream runs nearly from south to north, in a deep, but narrow and tortuous valley, terminated on both sides by lofty and perpendicular precipices of red sand rock. This sandstone {258} appears entirely to resemble that before mentioned, as occurring in an inclined position along the base of the mountains, on the Arkansa and Boiling-spring creek. Here it is disposed in horizontal strata of immense thickness; it varies in colour, from a bright brick red to a dark, and is sometimes grey, yellow, or white. It consists essentially of rounded particles of quartz and other siliceous stones, varying in size from the finest sand to gravel stones and large pebbles. Extensive beds of pudding-stone occur in every part of it, but are abundant somewhat in proportion to the proximity of the high primitive mountains. In the lower parts of the stratum these beds of coarse conglomerate appear to have the constituent gravel and pebble-stones more loosely cemented than in portions nearer to the upper surface; wherever we have met with them in immediate contact with the granite of the Rocky Mountains, they are nearly destitute of cement, and of a colour approaching to white. This remark, it is highly probable, may not be applicable to many extensive beds of pudding-stone which lie near the base of the mountains. In the instances which came under our notice, the absence of colour and the want of cement may very probably have been accidental. The finer varieties of the sandstone are often met with in the immediate neighbourhood of the granite, and are of a compact structure, and an intense colour. Red is the prevailing colour in every part of the stratum, but stripes of yellow, grey, and white, are frequently interspersed. In hardness and other sensible properties, it varies widely at different points. In many instances it is entirely similar to the sandstone about New Brunswick, in New Jersey, at Nyac, and along the Tappan bay, in New York, and particularly that variety of it which is quarried at Nyac, and extensively used in the cities of New York and Albany for building. It contains a little mica in small scales; oxyde of iron predominates in the cement, and the ore denominated {259} the brown oxyde, occurs in it in seniform botryoidar and irregular masses.