The flow of time in the Connecticut valley : $b geological imprintsBain, George W. (George William)
Science
The flow of time in the Connecticut valley : $b geological imprints
Bain, George W. (George William)
Geology -- Connecticut River Valley
Every stream has its load of sediment, as the silt- and sand-filled
reservoirs along the edges of the valley so effectively testify. Each
sandy river bed is an aggregate of rolling grains, moving with the
current, slow where it is slow and faster where the current is
accelerated, but travelling always towards the sea. Every grain is a
piece of the countryside lost to the land and soon to become a part of
the ocean floor. Very little of this sand comes from the lowland itself,
for the Connecticut may cut the bank below Hadley, but it leaves almost
as much sand as it acquires on the opposite shore. The river’s burden is
brought to it by swift tributaries—the brook at West Pelham and hundreds
more like it. Their sides are cut-banks, but no extensive sand bars are
built to balance their erosive work; what they pick up they carry to the
lowland, and what they bring to the lowland is soon transported to the
sea.
The contribution which the tributaries make to the lowland rivers was
demonstrated only too conspicuously by the great fans of coarse debris
spread across the valley of the Deerfield River and the West River
during the floods that accompanied the torrential rains of the
hurricane. Parts of the village of Townshend, Vermont, nestling in the
flat floor of the West River valley, were buried in gravel wash, and the
hillside roads above were gullied ten feet deep. One harassed traveler
aptly remarked that the original road level could be recognized from the
few concordant remnants of pavement beside the trout brook.
The hill slopes at Townshend rise and end near Jamaica, about one
thousand feet higher in elevation. Here the roads are in good condition.
There are no signs of erosion, and the rolling uplands extend for miles
with no signs of gullying or wash by the heavy rains.
The debris handled by the West River now and for ages past has come from
the steep hill slopes along the main valley. Each load of sand has cut
these slopes back from the main stream and has widened the lowland
floor. So, for millions of years, the tributaries of the Connecticut
have pushed the valley walls farther from the main river, and their
tributaries in turn have pushed their hill slopes back, while the valley
floors have steadily widened. The Connecticut Lowland was broadened in
this way, and the tributary Deerfield has developed its valley in
similar fashion but to a lesser degree. Today streams near the
headwaters acquire sediment, not from the upland across which they flow
to reach the deeply entrenched valleys, but from the steep slopes in the
most remote recesses of the upland on which they rise.
Public-domain text, read in full here on John Shaqi.
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