Westward from the Lower Tennessee river the surface of the East Gulf Coastal Plain rises rapidly to the summit of a broken cuesta or ridge and then descends gently and terminates abruptly in a bluff overlooking the Mississippi Flood Plain.
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.
As in all such forms, the Niagara cuesta has a relatively strong slope or infacing escarpment on the side towards the oldland, and a long gentle slope on the other side.
The cuesta would be straight from east and west if the slant of the strata were uniformly to the south; but the strata are somewhat warped, and hence the course of the cuesta is strongly convex to the north in the middle, gently convex to the south at either end.
High, overlooking the central denuded area of that state; and there, between the Brazos and Colorado rivers, occurs a series of isolated outliers capped by a limestone which underlies both the Llano on the west and the Grand Prairies cuesta on the east.
By the 10th of July Cuesta had joined Wellesley at Oropesa;, and both then moved forward to Talavera, Victor falling back before them: but Cuesta, irritable and jealous, Battle of would not work cordially with Wellesley; Venegas - Talavera, counter-ordered it is said by the Spanish junta - did July 27, 28, not go to Arganda, and Wilson, though he advanced 1809.
The cuesta begins where its determining limcstone begins, in west-central New York; there it separates the lowlands that contain the basins of lakes Ontario and Erie; thence it curves to the north-west through the province of Ontario to the belt of islands that divide1 Georgian Bay from Lake Huron; then westward throtigh the land-arm between lakes Superior and Michigan, and south-westward into the narrow points that divide Green Bay from Lake Michigan, and at last westward to fade away again with the thinning out of the limestone; it is hardly traceable across the Mississippi river.
In area, enclosed by bluffs one or two hundred feet high in the northern part, generally decreasing to the southward, but with local increase of height associated with a decrease in flood plain breadth on the eastern side where the Grand Gulf cuesta is traversed.
The most significant stage in this series of changes occurred when the glacio-marginal lake wateis were lowered so that the long cuesta of Niagara limestone was laid bare in western New York; the previously confluent waters were then divided into two lakes; the higher one, Erie, supplying the outfiowing Niagara river, which poured its waters down the escarpment of the cuesta to the lower lake, Ontario, whose outlet for a time ran down the Mohawk Valley to the Hudson: thus Niagara falls began.
Then comes the East Texas timber belt, broad in the north-east, narrowing to a point before reaching the Rio Grande, a low and thoroughly dissected cuesta of sandy Eocene strata; and this is followed by the Coast Prairie, a very young plain, with a seaward slope of less than 2 ft.