28 DE RANGE : UNDERGROUND WATERS IN LINCOLNSHIRE. 
g 1 L Lias Clay and Limestone. 
Except some small springs thrown out by an ironstone rock in 
the Middle Lias, at Bracebridge, at 45 feet above the sea level, no 
underground water is yielded by the Lias, and it may be regarded as 
an impermeable floor on which w r ater absorbed on the porous rocks 
lying above it are supported, and carried by their dip beneath the 
sea level, from whence they are prevented from rising by the over- 
lying impermeable Oolitic Clays. 
Above the Lias Clays occur the inferior Oolitic Basement Beds, 
consisting of the Northampton sand, and the overlying clays, shales, 
and sands of the Lower Estuarine series, varying much in character 
in different parts of the district. From Navenby to Burton four to 
eighteen feet of massive ironstone beds occur ; between Burton and 
Ingham clay and sands without ironstone replace the ironstone ; but 
northwards, the Northampton sands are represented by the compact 
hard ironstone called " the Dogger ;" the sands above at Ingham are 
also cemented into " pan," and associated with grey clay. 
These ironstone beds occur at about 200 feet above the mean 
sea level below the Cathedral, and dip eastwards, and descend beneath 
the sea level at a point on the Witham, half-a-mile on the Lincoln 
side of Washingborough Station, or 200 feet in two miles, which is 
equal to an inclination of rather more than two degrees in that direc- 
tion. Strong springs rise in a small combe about 200 yards south of 
the Wragby Road, and a little more than a mile E.N.E. of the 
Cathedral, which are due to the faulting of ironstone beds against the 
Lias. The structure of the ironstone varies from very compact to 
cellular, the latter being called " fire-stone " by the well-sinkers, who 
imagine the rock has been exposed to fire. 
Northwards from the gorge of the Witham at Lincoln, these 
various beds, capped by the Lincolnshire Oolite, form a fine escarp- 
