416 LOWER OOLITIC ROCKS OF ENGLAND : 
Referring again to Prof. Judd, we learn that at Ufford, a well 
was sunk through the hard limestone of the Great Oolite (which 
required blasting) into the green clays with Cyrena (Upper 
Estuarine Series) below it. 
" At Helpstone, a number of large pits have been opened in 
the Great Oolite Limestone, the stone being extensively quarried 
for road-metal, which is sent to considerable distances in the Fen- 
land. In a large stone-pit, containing a lime-kiln, above Help- 
stone, we have the following section " : 
FT. IN. 
Soil, &c. - - - - 2 
Great Oolite / Oyster-beds, with, bands of clay between 
Clay. I them - - 3 
Great Oolite J ck mass f.. ^ hard dark-blue 
{ limestone, with many shells 
Limestone. ^ to bottom of pit. 
" A well here, commencing at the top of the oyster-beds, and dug to the 
depth of 12 feet, just reached the top of the clays of the Upper Estuarine 
Series." Another well, noted by Prof. Judd, sunk at the western end of 
Helpstone, passed through Cornbrash and Great Oolite Clay (13 feet), 
into ferruginous rock that yielded :n abundance of water, but this, how- 
ever, was unfit for drinking purposes. Around Milton Park the Great 
Oolite Clay is from 15 to 30 feet in thickness, and is very variable in 
character. 
" At the railway-cutting near Overton Longville, at a place 
called Bottlebridge (St. Botolph's Bridge), the clays of the Great 
Oolite were exposed between the Cornbrash and Great Oolite 
Limestones. At this place the late Marquis of Huntly com- 
menced digging the ironstone-balls, which form four bands in the 
midst of the dark-blue clays. The ironstone in the upper bands 
was soft and of a dark-brown colour, owing to weathering action, 
but the lower bands were of a greenish-white colour, and un- 
oxidized, and every gradation between these two varieties 
occurred. The ironstone is said to have been of good quality, 
and between 100 and 200 tons of it were sent to Wellingborough 
to be smelted. Its exploitation was soon abandoned, owing to 
the quantity of material which had to be removed to obtain the 
nodules of ironstone."* In an excavation for the New England 
Gasworks, near Peterborough, the clays of the Great Oolite were 
found to have a thickness of 22 feet. At this locality a brickyard 
has been opened in the beds. (See p. 203.) 
In the brickyard at Stamford Field (Torkington's pit) Prof. 
Judd observed, in 1869, the following sectionf : 
FT. IN 
Soil 16 
Great Oolite \ yster-beds - - - .30 
Limestone. J J 
Dark-coloured, nearly black, carbona- 
ceous and ferruginous clay - 3 6 
Green clays, with shells - 3 
Clays of a tea-green colour, sometimes 
passing to a bright green, and 
crowded with shells - - 5 6 
* Judd. Geol. Rutland, p. 217. 
f Judd, Geol. Rutland, p. 199. 
