54 Lincolnshire Notes & Queries. 



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 under- 

 gone 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 consid- 

 erable 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 con- 

 figuration of the land is due. 



In order to understand this, we cannot do better than con- 

 sider how the gap through the Oolite escarpment at Lincoln 

 was formed, as from it we get a clue to all the rest. 



In 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 canons 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 power- 

 ful 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 uphill. 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-Brown, 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 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, Staffordshire, Warwickshire, and Leicestershire, 

 and it flows, as far as Newark, in a north-easterly direction ; 



