Figure 9, Plate I., shows the top of the De Beers' crater with basalt overlying the shale.
Its diaphanous, pearl-grey glaze, uniform, lustrous and finely crackled, overlying encaustic decoration in white slip, the fineness of its warm reddish pate, and the general excellence of its technique, have always commanded admiration.
At Vredefort there is a granitic boss, belonging to the Swaziland series, regarded as being an intrusive in the overlying Witwatersrand series by G.
The deposits in the great limestone caves of Kentucky, Virginia and Indiana have been probably derived from the overlying soil and accumulated by percolating water; they are of no commercial value.
In Cheshire the surface-water trickling through the overlying strata dissolves the salt, which is subsequently pumped as brine, but at Middlesbrough the great depth and impermeability of the strata precludes this, so another method has been resorted to.
Thus comparing the Nearctic and Palaearctic floras we find striking differences overlying the points of agreement already indicated.
Similarly it is necessary, in view of the hydrostatical relations of water and mineral oils, and the volatile character of the latter, that the porous stratum should be protected from water and air by an overlying shale or other impervious deposit.
When the land reappeared a new series of valleys would at once begin to be eroded; and the subsequent degradation of these overlying sediments might reveal portions of the older topography, as in the case of the Great Glen, Lauderdale, and other ancient valleys.
Rocks belonging to the Cretaceous system at one time covered considerable areas on both sides of the Highlands, but they have been entirely stripped off the eastern side, while on the western they have been reduced to a few fragmentary patches, which have survived because of the overlying sheets of basalt that have protected them.
The overlying Tertiary series includes nummulitic beds and valuable seams of coal.