THE MIDDLE LIAS OF NORTHAMPTONSHIRE 
279 
The badly preserved nature of the fossils at this quarry is 
no doubt due to the absence of a clay capping. 
When the first of the two quarries just described was 
being worked some twenty years ago a small fault was 
noticeable; and a figure of it occurs in the “ Memoirs of the 
Geological Survey,” description of sheet 45 of the maps. In 
this diagram the Upper Lias, with two of the lime¬ 
stone bands near its base, are shown abutting against 
the Middle Lias rock-bed at an angle of about 30°. The 
faulting was thought to be very slight, and the geo¬ 
logical maps show only a very small patch of Upper Lias 
let in. The construction of a well some fifty yards north¬ 
east of the quarry has, however, shown that the fault is 
much more extensive than had been anticipated, for the well 
being commenced about thirty feet above the level of the 
brook, passed through sixty-five feet of blue clay before water 
was obtained. The blue clay was very unfossiliferous; but 
Mr. Beesley, who was consulted in the matter, before water 
was obtained, identified it as Upper Lias by the foraminifera it 
contained ; this was afterwards confirmed by other fossils 
from the lower part. Mr. Beesley says, in a paper he read 
before the Banbury Natural History Society, that not far 
from this spot a well w 7 as sunk fifty feet in vain, and water 
only obtained by boring, when it rushed in with great 
violence ; also, that some wells at Lower Middleton Cheney 
are eighty feet deep, thus pointing to a probable extension of 
the fault in that direction. 
The Marlstone rock-bed is again met with in its normal 
position in Thenford, about a quarter of a mile north of the 
quarry; indeed, the main street has been partly cut through 
it, and it forms the foundation of walls of houses both here 
and at Middleton Cheney. 
About a quarter of a mile west of Thenford there is 
another Marlstone quarry (Boucher’s Pit), long disused, 
however. A distinct band of ossicles occurs about two feet 
from the top, the thickness of the entire bed being about five 
feet. It is capped by the Serpentinus and Fish and Insect 
beds, as in the quarry south of Thenford ; the Fish bed is, 
however, much better preserved. 
Still another quarry is to be seen a little way out of 
Thenford towards Middleton Cheney, but from long disuse 
very little besides the Communis beds of the Upper Lias can 
be now examined. 
Near to Middleton Cheney we again find Marlstone 
quarries, though few of them show signs of having been 
