The soil superimposed upon these strata of limestone, is a calcareous loam. Near the rivers it is intermixed with sand; this is also the case with the soil of the high prairies about the Konzas village. In ascending the Konzas river, one hundred, or one hundred and twenty miles from the Missouri, you discover numerous indications, both in the soil, and its animal and vegetable productions, of an approach to the borders of that great Sandy Desert, which stretches eastward from the base of the Rocky Mountains. You meet there with the orbicular lizard, or "horned frog," an inhabitant of the arid plains of {131} New Mexico. You distinguish also some cacti, as well as many of those plants allied to chenopodium and salsola, which delight in a thirsty muriatiferous soil. The catalogue of the forest trees belonging to the vallies of this region is not very copious. The cotton-wood and the plane tree, every where form conspicuous features of the forests. With these are intermixed the tall and graceful acacia, the honey locust, and the bonduc, or coffee-tree,[161] and several species of juglans, carya and fraxinus, with pinnated or many-parted leaves. Trees of the family of the coniferæ are not of frequent occurrence on the Missouri. About the summits of rocky cliffs are here and there a few cedars or junipers, the only trees that retain their verdure during the winter. The prairies, for many miles on each side of the Missouri, produce abundance of good pasturage; but as far as our observation has extended, the best soil is a margin from ten to twelve miles in breadth, along the western bank of the river. In the summer very little water is to be found in the prairies, all the smaller streams failing, even though the season be not unusually dry. On account of the want of wood and of water, the settlements will be for a long time confined to the immediate vallies of the Missouri, the Konzas, and the larger rivers; but it is probable, forests will hereafter be cultivated in those vast woodless regions, which now form so great a proportion of the country; and wells may be made to supply the deficiency of running water. We have seen at Bellefontain, as well as at several other points on this river, a pretty species of sparrow, which is altogether new to us;[162] and several specimens of a serpent have occurred, which has considerable affinity with the pine-snake of the southern states, or bull-snake of Bartram.[163]