412 LOWER OOLITIC ROCKS OF ENGLAND : 
by the percolation of chalybeate waters, a deep brown colour and 
great induration. He remarks that one of the most interesting 
pits in which these characters are displayed, lies to the north-east 
of Benefield, where we find the following succession of beds : 
FT. IN. 
r Sandy gravel, containing small, irre- 
gular pebbles of brown oxide of iron, 
Drift, &c. ^ derived from the Northampton Sand. 
! Breccia of argillaceous limestone and 
1_ clay, fnll of Great Oolite fossils. 
f" - - 
Hurr," beds almost wholly made up 
of small oyster shells, and in their 
upper part indurated and stained 
Great Oolite j of a dark brown colour by oxide of 
Limestone. j iron* - ... about 2 
Blue clay - - - - 1 
Beds of good stone to bottom : quar- 
ried in places to depth of - - 9 
" Another peculiarity of the Great Oolite Limestone, as seen 
in the neighbourhood of Oundle, is well displayed in a pit between 
Upper and Lower Benefield. Here the bottom-beds of the series, 
which can be raised in very large slabs and blocks, exhibit much 
false-bedding and are crowded with shells ; they also contain 
fragments, usually subangular, of a compact limestone possibly 
derived from the Lincolnshire Limestone, and indicating the 
denudation which those beds suffered prior to, and during, the 
deposition of the Great Oolite." The stone-beds of the Great 
Oolite here present the aspect of Forest Marble. The Great 
Oolite Clay is little more than 3 feet thick ; and therefore, as 
Prof. Judd remarks, no attempt was made to separate it from 
the Limestone on the Geological Survey Map, in this part of 
the district. 
" The * town-pit ' of Apethorpe is opened in the lowest hard 
bed of the white limestone. It is here about 16 inches thick, and 
is overlaid by hard, cemented, limestone rubble. It is underlaid by 
a bed of marl, and that in turn rests on a bed of stone 4 inches in 
thickness. Below this we find a great mass of light- blue clay 
belonging to the Upper Estuarine Series. Along the line of 
the valley by King's Cliffe, Apethorpe, and Wood Newton to 
Fotheringhay, a number of small pits occur by means of which the 
general succession of the Great Oolite beds may be traced/' f 
Below Calvey Wood, on the Walk of Morehay, south of King's 
Cliffe, the Great Oolite Clays " are seen below the Cornbrash, 
and are found to contain numerous branch-like concretions of 
brown oxide of iron, like those of the equivalent beds at New 
England, near Peterborough." 
" On the Bedford Purlieus the beds of Great Oolite Limestone 
are exposed in some small openings, and are also reached in two 
of the wells dug on parts of the old forest-land which, at the time 
* There is a specimen of this Oyster lied in the Museum of Practical Geology, 
j- Judd, Geol. Rutland, pp. 205, 207, 216, 217; see also Sharp, Quart. Jouru. 
Geol. Soc., vol. xxix. p. 280. 
