274 BURTON : THE STORY OF THE LINCOLN GAP. 
surface over which they began to run.’ This being borne in mind, 
what evidence is there to show that the Trent once flowed through 
the gap on which Lincoln is built? 
The river itself is one of considerable volume. It is the combined 
issue of several streams, having their sources in Derbyshire, Stafford- 
shire, Warwickshire, and Leicestershire, and it flows, as 
Newark, in a north-easterly direction ; there, however, it leaves its 
course and bends to the north, skirting the low Triassic and Rheetic 
escarpment on the west, ‘as if it had not been able to cross that 
comparatively slight obstruction’; then, continuing past Gains- 
Ww 
Newark, is of comparatively recent origin, and that it formerly con- 
tinued its north-easterly course and flowed through the gap at 
Lincoln, is capable of proof; and the credit of suggesting this is due 
to Mr. Penning, of the Geological Survey, when he was engaged, in 
1878, in mapping the gravel beds round Lincoln. 
ow what are the proofs? First, it is, as Mr. Jukes-Browne says 
in his paper before referred to, ‘a significant fact that if the general 
course of the Trent, south-west of Newark, be prolonged to the 
north-east, it points to the great gap in the Oolitic escarpment at 
Lincoln through which the river Witham now flows’; but it is more 
significant to find that, all along this north-east tract, lie vast beds of 
ancient gravel deposits, showing clear traces of river action, distinct 
from the other and more modern gravels around (which latter, as 
I shall show later on, are the result of floods to which the Trent has 
always been greatly liable) ; and still more significant is the fact that 
these ancient gravel beds carry with them incontestable proofs of 
their origin, being ‘largely made up of rounded pebbles of quartzite, 
hornstone, and other old rocks, which have evidently been derived 
from the Triassic pebble-beds, beyond Newark, on the west’; and as 
these ancient gravels, with their component pebbles, are found 10 
large quantities, not only between Newark and Lincoln to the west of 
the gap, but right through and far beyond it on the east, they could 
have been brought there only by the Trent, otherwise there is NO 
way of accounting for them. 
All this is, I submit, sufficient to convince any reasonable mind 
that the present course of the river Trent is not its original one, but 
that, ages ago, in early pre-glacial times—(as I think), and not post 
glacial, as Mr. Jukes-Browne suggests—it passed through the Lincoln 
Gap to the fen-land beyond, which was then, probably an open bay. 
We have now to enquire how the change came about ; and, to under- 
stand it, we must learn something of the laws relating to river courseS- 
sauna 
Naturalist, a 
