Aggraded Sentence Examples
When the ice sheets fronted on land sloping southward to the Ohio, Mississippi and Missouri rivers, the drift-laden streams flowed freely away from the ice border; and as the streams, escaping from their subglacial channels, spread in broader channels, they ordinarily could not carry forward all their load; hence they acted not as destructive but as constructive agents, and aggraded their courses.
The load of silt borne down stream by the river finally, after many halts on the way, reaches the waters of the Gulf, where the decrease of velocity, aided by the salinity of the sea water, causes the formation of a remarkable delta, leaving less aggraded areas as shallow lakes (Lake Pontchartrain on the east, and Grand Lake on the west of the river).
Many of the intermont plainsthese chiefly in the north-appear to be heavily aggraded with mountain Waste; while others-these chiefly in the southare rock-floored and thinly veneered with alluvium.
The tilting of the mountain mass was presumably not a simple or a single movement; it was probably slow, for Pitt river (headwaters of the Sacramento) traverses the northern part of the range in antecedent fashion; the tilting involved the subdivision of the great block into smaller ones, in the northern half of the range at least; Lake Tahoe (altitude 6225 ft.) near the range crest is explained as occupyilig a depression between two block fragments; and farther north similar depressions now appear as aggraded highland meadows.
South of Mt Shasta, the Valley of California is an admirable example of an aggraded intermont depression, about 400 m.Advertisement
Exception to this statement must be made in the south-west, close to the mountains in southern Colorado, where some lava-capped mesas (Mesa de Maya, Raton Mesa) stand several thousand feet above the general plain level, and thus testify to the widespread erosion of this region before it was aggraded.
In the southern part of the Basin Range province the ranges are well dissected and some of the intermont depressions have rock floors with gentle, centripetal slopes; hence it is suggested that the time since the last dislocation in this part of the province is relativel remote; that erosion in the current cycle has here advanced muc farther than in the central or northern parts of the province; and that, either by outwash to the sea or by exportation of wind-borne dust, the depressions-perhaps aggraded for a time in the earlier stages of the cyclehave now been so deeply worn down as to degrade the lower and weaker parts of the tilted blocks to an evenly sloping surface, leaving the higher and harder parts still in relief as residual ranges.