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254 WOODRUFFE-PEACOCK : NATURALISTS AT GAINSBOROUGH. 
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Going northwards over the Common, we crossed the Rheetic 
strip again at the foot of Hardwick Hill, and got once more on 
the Keuper. This hill stands out as a landmark which can be se 
from a great distance, and from it, a very fine view of the Trent 
valley, before it merges into that of the Humber, is obtained. It is 
difficult at first sight to believe that this wide area was once—and 
within comparatively recent times—high ground, through which 
a few miles further to the north, the Humber—then a comparatively 
small river—flowed eastwards to the sea; and that so wide a valley 
as we now see is the result of the gradual drainage of the land 
on the Humber side. At first the only sign ofall this waste of 
the land would be a mere rift or gully, down which would flow 
a little stream ; but, as the Humber deepened its bed, the rift would 
grow wider and deeper year by year, the stream would increase in 
volume, ‘a rivulet then a river,’ until, at last the lateral valley we 
now see was formed—of such extent that the head of it reached the 
Trent on the south, tapping its waters, and-compelling it to change 
its old course through the Lincoln Gap for its present bed. 
This Keuper outcrop, forming Hardwick Hill, stood out once 4 
a low headland on the Trent side, when the river ran at a higher 
level than it does now; and, on it, the capping of sand and gravel, 
which has for years protected the underlying Keuper. beds from the 
rain and forces of the atmosphere, and prevented them from being 
swept away, was deposited. 
Descending Hardwick Hill on the northern side, we got 0D the 
alluvium of the Trent, with patches of blown sand, here and there, 
at intervals. This blown sand is met with in vast quantities over 
large areas to the east of the Trent ; and, wherever it comes 10 
contact with the alluvium it passes under it, showing that the san 
the earlier, or older formation of the two. These sand-beds are 
a feature of great interest in this neighbourhood. They are found, 
not only on the borders of the Trent valley, but much further inland ; 
and, wherever they are met with, their rounded, dune-like nae 
show their zolian origin. They were formed when the Trent flowe 
at a much higher level than it does now, and when the tides were 
probably stronger; and they are the result of wind action, blowing 
up the loose, low-lying tracts of sand over the elevated ground on 
the east. 
Messrs. A. Fieldsend and F. M. Burton have drawn UP the 
following list of birds observed, and I have added a few notes ae 
my thirty years’ experience of the ground. Black-headed - O°: 
Old birds, first year birds, young and eggs in vast numbers. ee 
_ gull pond is an offshoot from the famous ponds at Trig 
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