BOTANICAL INFORMATION. 487 
Lathyrus ornatus, Anemone tenella and Pennsylvanica, and 
Hymenopappus corymbosus. In wet places may be seen groups 
of Iris Virginiana, and Tripsacum monococcon, mingled with 
Carices, Eryngium aquaticum, and Zigadenus glaberrimus. 
On arriving at the Platte, the aspect of the country is 
entirely changed, and a comparative barrenness takes place. 
Here commences the | 
II.— Or less fertile region, lying between the Saline desert 
of Upper Platte, and the last named fertile prairie region of 
Kanzas river. 
Surface and apparent geological features.—' The land having 
risen to an elevation of about 900 or 1000 feet, it loses that 
pleasing undulated surface, characteristic of the western 
prairies. The tabular plains commence, though at first much 
interrupted by abrupt, steep ravines, and intervening ridges. 
They are composed of a coarse gravel, bedded on a massive 
layer of boulders of every sort of so-called primitive rocks, 
especially granite, and these again rest on recent horizontal 
sandstone, which latter overlays masses of bituminous shale 
of amazing depth. Piles of that sandstone are met with 
here and there, variously inclined, having been evidently 
dislodged from the level position, denuded of the soil by the 
weather, and are now walled at their bases with the accumu- 
lated boulders. In deep abrupt ravines, the water-courses 
are on bituminous shale, while the steep sides present to 
view the horizontal interrupted layer of the new sandstone 
stratas. This sandstone is of a coarse grain, and argillaceous 
cement, the latter preponderating ; hence it is easily decom- 
posed by the action of the atmosphere. _ d 
General features of the vegetation.—The woods are now 
reduced to groves only of Populus Canadensis, Mx., Ulmus 
Americana and fulva, Negundo fraxinifolium and Celtis occi- 
dentalis. A very small grove of Quercus macrocarpa occurs at 
the most northerly spur of the Black Hills, almost out of this - 
region. The thickets consist of Rhus glabra, Rosa parvifolia, — 
Amorpha frutescens, Salix longifolia, and Rubus occidentalis. 
Among the grasses, Avenacee and Festucaceæ take the lead, 
