273 
THE STORY OF THE LINCOLN GAP. 
F. M. BURTON, F.L.S., F.G.S., 
President of the Lincolnshire Naturalists’ Union, being the Presidential Address, 
delivered at Lincoln, 1895. 
A TRAVELLER starting from the Trent side, and journeying eastwards 
across Lincolnshire, might reasonably suppose, as he met with escarp- 
ment after escarpment—first the Triassic and Rheetic, then the Oolitic, 
and lastly that of the Chalk, with, here and there, lesser intermediate 
tidges—that the sea had been at work in forming the surface of the 
land ; but his impression would be wrong. True that, since the land 
rose from under the deep chalk ocean, it has undergone various 
periods of subsidence, elevation, and rest, and has been covered by 
the waters of the sea at various times; true that, in the ice period, 
the whole of the land sank to a considerable depth below its present 
level, and, therefore, true that the surface has been to some extent 
modified by the sea—yet, for all that, there are distinct proofs, both 
positive and negative, that it is to the action of rain and rivers that 
the present configuration of the land is due. 
In order to understand this, we cannot do better than consider 
how the gap through the Oolite escarpment at Lincoln was formed, 
as, from it, we get a clue to all the rest. 
n my address last year I alluded to a great river system coming 
from the South and West, the only remains of it being the Witham. 
Rivers cut narrow gorges or channels, and it is left to rains and 
sub-aerial forces to widen them into valleys. The fiords of Norway 
and the cafions of America are the work of rivers; but no one will 
give the Witham the credit of having cut through the Lincoln Gap, 
SO we must look for a more powerful and efficient agent, and we find 
it in the Trent. 
In considering this, it is most important that we should bear in 
mind the difference in the height of the land before the gap was 
formed, and at the present time. 
To enable a river to cut through rocks, whether hard or soft, it 
must, of necessity, start from higher ground than the land it runs 
Over; it must, in fact, have a downward slope to work on, and 
cannot go up hill. The land, therefore, to the West of Lincoln must 
at one time have been higher, instead of lower, than the present cliff, 
Otherwise the gap could not have been made}; or, as Mr. Jukes- 
Browne, in his paper ‘On the relative ages of certain river-valleys in 
Lincolnshire,’ puts it: ‘The original direction of all rivers which cut 
through ridges was determined by the general slope of the ancient 
Sept. 1895. " 
