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Such are the hills of Monte Alegre, of Obydos, Almeyrim, and Cupati, as well as the lower ridges of Santarem. This escape of the waters did not, however, entirely empty the whole basin; for the period of denudation was again followed by one of quiet accumulation, during which was deposited the ochraceous sandy clay resting upon the denudated surfaces of the underlying sandstone.
These latter, however, never rise so high as the ochraceous clay, but are everywhere confined within the limits of high and low water.
If this be so, it is evident, on comparing the two formations, that the ochraceous sandy clay of the Valley of the Amazons has been deposited under different circumstances; that, while it owes its resemblance to the Rio drift to the fact that its materials were originally ground by glaciers in the upper part of the valley, these materials have subsequently been spread throughout the whole basin and actually deposited under the agency of water.
At the Cape of Good Hope, at the base of the mountains formed of granite and capped with sandstone, the ground is everywhere coated either by a fine-grained, rubbly, ochraceous mass, like that at King George's Sound, or by a coarser sandstone with fragments of quartz, and rendered hard and heavy by an abundance of the hydrate of iron, which presents, when freshly broken, a metallic lustre.
The unconformability of the ochraceous clay and the underlying sandstones might lead to the idea that the two formations belong to distinct geological periods, and are not due to the same agency, acting at successive times. One feature, however, shows their close connection. The ochraceous clay exhibits a remarkable identity of configuration with the underlying sandstones.
The second metamorphosed variety is likewise a hard rock, but without any crystalline structure. It consists of a white, opaque, compact, calcareous stone, thickly mottled with rounded, though regular, spots of a soft, earthy, ochraceous substance.
The students of a seminary were hurrying in serried ranks along the Quai de Billy, and the trail of cassocks acquired an ochraceous hue in the diffuse light. Farther away, vehicles and foot-passengers faded from view; it was only by their gleaming lamps that you were made aware of the vehicles which, one behind the other, were crossing some distant bridge.
At its mouth, near the town of Souré, and at Salvaterra, on the opposite bank, may be seen, lowest, the well-stratified sandstone, with the finely laminated clays resting upon it, overtopped by a crust; then the cross-stratified, highly ferruginous sandstone, with quartz pebbles here and there; and, above all, the well-known ochraceous, unstratified sandy clay, spreading over the undulating surface of the denudated sandstone, following all its inequalities, and filling all its depressions and furrows.
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