Regarding the existing flat-topped heights among the eastern Grampians as remnants of what was once the general character of the surface, we can trace every step in the gradual obliteration of the tableland and in the formation of the most rugged and most individualized forms of isolated mountain.
In the east the tableland falls away to the basins of the Congo and Zambezi, to the south it merges into a barren sandy desert.
Of the Canadian rivers lies the great arid tableland known as the Staked Plains (Llano Estacado), a vast stretch of barren wastes, with almost nothing to break the monotony of its landscape.
The most elevated tracts are on the west, where the surface rises towards the culminating range of hills, and on the south, where it rises to the elevated tableland of Mysore.
As the tableland runs northward it decreases both in height and width, until it narrows to a few miles only, with an elevation of scarcely 1500 ft.; under the name of the Blue Mountains the plateau widens again and increases in altitude, the chief peaks being Mount Clarence(4000 ft.), Mount Victoria (3525 ft.), and Mount Hay (3270 ft.).
To the south of the district in southern Westland, where the Alps have passed out to sea, the Archeans become more extensive; for they spread eastward and underlie the whole of the dissected tableland of Otago.
The great Brazilian plateau, which is the most important physical division of Brazil, consists of an elevated tableland moo to 3000 ft.
In the east a tableland of sandstone, called Saxon Switzerland, from the picturesque outlines into which it has been eroded, adjoins the Erzgebirge; one of its most notable features is the deep ravine by which the Elbe escapes from it.
From these lofty ranges there extends a broad tableland (in many parts more than 3000 ft.
In a basic neck of this period at Inverell, there are eclogite boulders, containing diamonds in situ; and it is doubtless from these basic volcanic necks that the diamonds of the New England tableland have been derived.