The Potter journal and news item. [volume] (Coudersport, Pa.) 1872-1874, 1873-04-25
SITS 4 YEAR

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of il. at intervals, are verdure-cover-
ed meadows and deposits Of shlngle
and sand, overhowed during periods
of rain and freshet. These constitute
what may be termed the river-hats
or hood-plains. Something is added
10 il during each overflow. Mean
while the river-channel is deepening
BY the wearing action of the current
and transportation Of the materials
Of its bed. At length the waters are
discharged along the channel and no
longer overflow the food-plsins,
which become at once q terrace. the
last formed the newest of the series,
the oldest of which may be more than
q thousand feet mp the bank.
/ The newly-nade terrace now really
forms the bank or banks of the
stream. and is itself slowly worn
away and distributed elsewhere by
the abrasion of annual freshet>.
Portions Of it may thus disappear
but other portions remain.
1t is obvious that terrac. -Eorma-
tions occur in greatest perfection
where the stream is not very rapid.
Where it flows a. a torrent food.
plain or delta may form only at its
mouth. Sometimes. however. swift
stream l. checked by the accumuls-
ton Of debriS or by rocky gorges,
forming lake-like basins around which
terracc-fonnations occur with great
uniformity and beauty. The Con
necticut River Is 1889 feet higher al
it, source than at its mouth; and, ac-
cUrding 10 Prof Hitchcock's : excel
lent report on the Surface Geology
Of New England, twenty-five snch
basins or levels occur in its descent.
II is evident. as We have observed,
that the highest terrace of a series is
the one first formed and the oldest,
but when formed was equally, with
the last one, the flats or food-l lain
Of the river; whence it follows that
the river was then much higher, -
regards the general level Of the land.
than row. lis present deep valley
was not cxcavated, but il BY no
means follows that the river was any
higher as regards the level Of the SEA.
\ change Of level has. indeed, taken
place, but it has been oil the land. not
of the ocean. No truth in geology
i better established than this perpet-
ual oscillation OF the crust OF the
GLOBE and from the unchanging
ocean-leyel i measured the extent Of
the movement.
The process 10y which a river-val-
. !ey i excavatcd and terraces formed
upon its banks l. directly connected
wife this elevation Of the land. In
deej, it could occur only during
period Of elevation AMI may have
commenced with the emcrgence OF
the land above the waters, for then
would begin the flowing Of streams
and their concentration into larger
ones, forming at last our magnificent
system Of rivers. During period
Of subsistence, however, the rivers
disappear a. their valleys are filled
aud the land j. overfowed hy the in
vadiDg ocean. Nor i proof wanting
Of submergence Of a very large por-
tion Of this continent, especially that
which i north Of the for,ieth paral-
lei, directly following the Glacial ani
preceding the Terrace Epoch; and
nowhere il that fact more apparent
than in New England.
The occurrence Of ancient btachcs
above the terraces on Hoosac Noun
tain and among the White and Green
Mountains 2200 AMI 300 feet above
the ocean. proves its former presence
: and the movement Of It's currents and
waves.
At that period the site Of the pres
ent river was the bottom Of an ocean.
II was during the progress of that
period Of continental depression and
subDergence that the glacial drift
was modified and re-distIibuted,
forming enormous deposits filing
old basins and river-valleys, SO that
when the land emerged from the Wa
ters it was comparatively level. few
mountajn-reaks rising above the
plain.
II is at this point, IS VI have seen
that the present riyer-system with It's
terraced valleys begin and the ple-
nomena way occur i'll the following
order:
l. Elevated beaches, indicating
ancient sea-shores.