One of these pools lies in the valley of the Rongtham river, to the
south of the Samin fault. It seemed, at first sight, to be nothing
more than an ordinary pool, such as may be seen on any mountain
stream. On the bottom, and close to the outlet, however, are coarse,
partially rounded boulders, exactly resembling those farther down the
river; and, as the old bed was followed up, these became coated with a
slight deposit of sand and mud, pointing clearly to a change in the
conditions under which they were formed. The water gradually deepened,
until trees were met standing in the water, but killed by the recent
submergence of their roots. The pool is nearly a quarter of a mile
long, and its greatest depth (12 feet) occurs near the middle, just
where the former stream, with an average depth of about a foot, was
crossed by the track from Darangiri. Towards the upper end, the water
shallows as gradually as it deepens at the other, and ends in a delta
of boulders brought down by the stream above. As no fault could be
discovered in the neighbourhood of the pool, it is evident that its
formation was due to a bend of the river-bed, the maximum change of
level, taking into account the river-slope, being not less than 24
feet.
Similar features characterise the other pools that were examined, some
of which are smaller, and others larger, than that described above.
One, higher up the valley of the Rongtham, has a length of about 1-1/2
mile and a maximum depth of 18 feet. Others of the same type, but of
smaller size, were observed among the Khasi hills, about fifteen miles
south of the Bordwar fissure; and it is probable that many others
would have been found in the intermediate district, which Mr. Oldham
was unable to visit.
_Changes in the Aspects of the Hills._--There are, again, other facts
of considerable interest which point to changes of level over a wide
area; the places where they were noticed being indicated by small
circles in Fig. 75. For instance, from Maophlang, near Shillong, a
road leads to the neighbouring station of Mairang. Before the
earthquake, only a short stretch of this road could be seen from the
former place, as it rounded a spur about three miles away. Now, a much
longer stretch is visible, and it can also be seen passing round the
next, and previously hidden, spur. In this district the movements seem
to have continued with the after-shocks; for, before the earthquake,
the crest only of a ridge about a mile and a half to the west was
visible; while, after it, a considerable portion could be seen, and
much more some months later than immediately after the shock.
Again, from a spot near the southern end of the Chedrang fault, it
used to be only just possible to see the Brahmaputra over an
intervening hill; whereas, now, the whole width of the river has come
into view.
Public-domain text, read in full here on John Shaqi.
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