GEOLOGY SOUTH OF GRANTHAM. 
A Paper Read at the Meeting of the L.N.U. at Grantham, 7th June 1898. 
HENRY PRESTON, F.G.S. 
WHEN the Lincolnshire Naturalists’ Union visited Grantham in 
June 1896, some features of the surface geology of the district 
lying north of the town were described (see ‘ Naturalist,’ Sept. 
1896). It is now proposed that the Union shall make another 
visit and deal with the country lying south of Grantham as far 
as Colsterworth. 
Geologically, the ground over which we shall pass is not so 
varied as the district to the north, nor has it been subjected to 
Such a vast amount of denudation, hence the rock formations 
cropping out at the surface are less numerous and the surface 
features are more uniform in character. 
It will be seen from the diagram, Fig. 1, that, with the 
exception of a few small river valleys, nearly the whole surface 
to be visited consists of Lincolnshire Limestone and Boulder 
Clay, and it lies wholly within Sheet 70 of the Ordnance Survey. 
The sections to be seen on this visit will not be 
numerous ; they comprise Plateau Gravels, Lincolnshire Lime- 
of denudation of the Boulder Clay. It consists of rounded and 
smoothed pebbles of Inferior Oolite, Liassic Limestones, Marl- 
stone, Carboniferous Limestone and Sandstone, with a few 
Flints and very few Quartzites, Igneous Rocks, or hard Paleozoic 
Rocks. From this pit I have collected representative fossils of | 
Mountain Limeston ne, Lower and Middle ias, Lincolnshire 
olite, Great Oolite Limestone, Cornbrash, and Oxford an 
Kimeridge Clay. These, together with other fossils referred to, 
The Lincolnshire Limestone was described on your former 
visit, and it will suffice upon this occasion to mention that it 
is an Oolitic Limestone, averaging about 100 feet thick, rather 
variable in lithological character, sometimes yielding coarse 
shelly rag-stones, and at other times good beds of valuable 
freestones. 
The Northampton Sands are here very variable. They often 
show alternating beds of brown, purple, green and black a 
with irregular beds of sands, often very ferruginous or 
? careous, and again pure white leas of silica, At Colsterworth : 
