156 
THE CRETACEOUS ROCKS OF BRITAIN. 
These immature flints were first found in a lane south-east of 
Eastcott, and were described by Mr. Hill and myself in 1889.* 
The folio whig description is taken from the account there given : 
“ One of the beds contains many definite siliceous concretions of 
irregular shapes, comparable to nodules of flint or chert, but 
unlike such nodules in being so closely united with the surrounding 
matrix that they are not readily separated from it. They are very 
hard ; when broken they are seen to be of a yellowish or bluish-grey 
colour, with a dull earthy fracture which is quite different from 
that of flint. Examined with a lens, the fractured surface is seen 
to be rough and granular, and has somewhat the appearance of a 
piece of grey chalk which has been hardened by an infiltration of 
gum or cement.” 
Stratigraphical Details. • 
Zone of Ammonites varians. 
Chloritic Marl. —The basement bed of the Chalk is well ex 
posed at several localities in this district. It is generally a bed full 
of phospliatic nodules and fossils, and the occurrence of Stauro - 
nema Garteri proves it to be the continuation of the subzone 
characterised by that species. Only in one locality (Urchfont) has 
any bed been observed that might be compared with the subzone 
of Catopygus columbarius at Maiden Bradley. In most places 
north of the Vale of Pewsey there are signs of erosion at the base 
of the Stauronema zone. 
One of the best exposures is that in the lane south of Urchfont 
where the following succession was seen in 1888 : — 
ft. in. 
. f Light-coloured glauconitic marl, with phosphatic nodules 
I passing down into very sandy marl, highly glauco- 
g I nitic, with many phosphates - - - - - 6 0 
'-Thin continuous layer of phosphatic nodules. 
li ( Greensand, somewhat marly, with scattered plios- 
| ) phates and Pecten asper, passing into next - - - 0 6 
g 1 Hard glauconitic sandstone, with Pecten asper - 1 0 
O [ Greenish-grey sand, with doggers of sandstone - - 5 0 
The Selbornian part of this section has been described in a pre¬ 
ceding volume. There is really a complete passage here from Green¬ 
sand to Chalk, and though the above grouping represents my im¬ 
pression at the time it is possible that the six inches of green sand 
above the sandstone represents the Bye Hill sand. Eossils are 
abundant in the overlying Chloritic Marl, and a list of those 
obtained in two hour’s search is given on p. 163. 
The junction is seen again in the railway-cutting at Stert, but 
though this is less than two miles distant the beds have changed 
considerably, for at Stert the sands pass up into marly sand, and 
this becomes gradually harder and more marly, becoming a glau- 
* Quart. Journ. Geol. Soc., Vol. xlv. p. 403. 
