252 Preston: Geology South of Grantham. 
stone rock which is being rapidly denuded away by the various 
springs rising within it. These streams, coupled with the 
action of wind and weather, will in time clear away the whole of 
this limestone, and the underlying rocks of the Liassic series 
will become the surface rocks. Such rapid denudation cannot 
possibly take place on the east side of the Witham, hence we 
may picture to our minds a time when the Lincolnshire cliff will 
extend southwards for several miles beyond its present limit 
at Grantham 
Besides the direct action of the streams in wearing away this 
mass of limestone, it eles be interesting Bs notice a secondary 
cause helping to remove i 
In the autumn of A) the Waterworks Company had 
occasion to lower one of their supply mains across the hill 
marked a 6 in map, Fig. 1. In the survey map this hill is 
shown capped with Plateau Gravel, and a pit in this gravel will 
be seen at Little Ponton. 
The trench cut by the Waterworks Company extended for 
about 500 yards in a W.S.W. direction, and in the deepest part 
was 22 feet deep. Very little of the gravel was met with, but. 
limestone was reached at a depth of 6 feet from the surface 
From the sketch of the section, Fig. 2, it will be noticed that 
the contour of the hill is one uniform curve, but it was soon 
Fig 2 
found that the rock surface did not follow the contour of the 
ground. Various beds of Boulder Clay were met with and some 
was a series of valleys, or large fissures running approximately 
and S. direction. These fissures, or swallow holes, were 
generly filled with a red marl, and the sides were inclined at 
thin beds of sand and gravel, but the most remarkable feature’ _ 
Naturalist, re 
