By far the greater proportion of this section of country is characterized by a rolling and plain surface, which may be alleged not only of the space included within the limits above assigned, but of extensive portions of country north and south of it. Although the elevated table-lands, a description of which has just been given, are situated within this region, they occupy but a small proportion of it. In addition to these inequalities in the surface of the country, there are numerous mounds or knobs of different magnitude, and occasionally swells of greater {225} or less extent, which contribute to give a pleasing variety to the prospect. The country is also divided into extensive parterres by the valleys of rivers and creeks, which are usually sunk 150 or 200 feet below the common level, and bounded in some places by perpendicular precipices, and in others by bluffs, or banks of gentle slopes. Immediately at the base of the mountains, and also at those of some of the insular table-lands, are situated many remarkable ridges, rising in the form of parapets, to the height of between fifty and one hundred and fifty feet. These appear to have been attached to the neighbouring heights, of which they once constituted a part, but have, at some remote period, been cleft asunder from them by some extraordinary convulsion of nature, which has prostrated them in their present condition. The rocky stratifications, of which these ridges are principally composed, and which are exactly similar to those of the insulated table-lands, are variously inclined, having various dips, from forty-five to eighty degrees. Throughout this section of country the surface is occasionally characterized by water-worn pebbles, and gravel of granite, gneiss, and quartz, but the predominant characteristic is sand, which in many instances prevails almost to the entire exclusion of vegetable mould. Large tracts are often to be met with, exhibiting scarcely a trace of vegetation. The whole region, as before hinted, is almost entirely destitute of a timber-growth of any description. In some few instances, however, sandy knobs and ridges make their appearance, thickly covered with red cedars of a dwarfish growth. There are also some few tracts clad in a growth of pitch pine and scrubby oaks; but, in general, nothing of vegetation appears upon the uplands but withered grass of a stinted growth, no more than two or three inches high, prickly pears profusely covering extensive {226} tracts, and weeds of a few varieties, which, like the prickly pear, seem to thrive best in the most arid and sterile soil.