BOTANICAL. INFORMATION. 33 



white calcareous cement, this conglomerate includes fragments 

 of primitive rock and of secondary, all rounded and smoothed, 

 from the size of small pebbles, to one or two feet in 

 diameter. This conglomerate makes up the mass of 

 the Black Hills, their centre being, as has been already 

 stated, syenitic ranges. A very different, and : 



B. — Low range of hills occurs at the end of this, or near 

 the detached mountains, based on, and overtopped by the 

 iron sandstone, the latter again leaning on syenite and 

 granite. This range of hills, known by the name of " Red 

 Butts," is composed of blood-red sandstone, intermingled 

 with micaceous clay of the same colour, forming a curious 

 front of sundry rounded cupola-like corners and high vertical 

 escarpments.* The conglomerate is in some localities 

 above, but ordinarily below the 



C. — New sandstone. A very extensive stratification which 

 constitutes most part of the hills and mountains of this 

 group. When undisturbed, it lies strictly horizontally ; 

 is found often imbedded, as a thin layer, in ferruginous 

 sand or shale; is coarse-grained, with an indifferent friable 

 argillaceous cement, and of a dirty-white or brownish colour. 

 Its highest localities are the high plateaux about the sources 

 of Missouri, where it has been lifted up by basaltic rocks 

 from beneath. It occurs fantastically- shaped, in obelisks, 

 towers, castles, &c, by the effect of weather, as for example, 

 the " Chimney" on the Platte, or the immersed sandstone 

 ranges in the shape of ruins of cities on the Upper Colorado. 

 Finally, it alternates sometimes, as has been stated, but gene- 

 rally overlies the 



D. — Vast stratified beds of carbonaceous bituminous 



* Part of the valley near these escarpments is cavernous, as the sound 

 of our horses' feet sufficiently indicated. Evidently the red colour was 

 imparted to this sandstone by heat. The clay banks and clayey sandstone 

 rocks opposite were likewise heated for a considerable distance, even the 

 banks and bottom of a small rivulet, as the red colour and baked ap- 

 pearance of the clay sufficiently indicated. The other portions of the valley 

 are wider, and are saline meadows. 



VOL.. V. D 



