The occurrence of the lake basins in the lowland belts on either side of the Niagara cuesta is an abnormal feature, not to be explained by ordinary erosion, which can produce only valleys.
In the embayment of the coastal plain some low cuesta-like belts of hills with associated strips of lowlands suggest the features of a beltedcoastal plain; the hillybeltordissected cuesta determined by the Grand Gulf formation in western Mississippi is the most distinct.
Most of the plain is treeless prairie, but the sandier belts are forested; two of them are known as cross timbers, because their trend is transverse to the general course of the main consequent rivers.
All the nine climate belts in the United States, except that of southern Florida, are represented within its borders.
The stretch from Samsat and Jeziret-ibn- 'Omar to the alluvial plain seems to divide itself naturally into three parallel belts, highland watershed district, un- Geography.