: MIDDLE LIAS: GRANTH.YBT, 239 
The lower beds of the Middle Lias in this area are from 8 to 
120 feet thick. 
Near Holweli the Marlstone is underlaid by blue shaly clays 
which rest on about 4 feet of green and brown micaceous sands, 
and these again repose on blue clays with nodules of ironstone. 
There are several iron- works at Hoi well, and from 12 to 14 
feet of ironstone has been exposed, but there is no more than 10 
feet of good ore, and this is reduced to 5 feet in places. Sandy 
beds occur at the base. When worked into the hill, the ironstone 
is said to become too hard and too limy to be used with profit, 
in fact it then needs to be blasted. Crinoidal beds occur here and 
there in lenticular masses, as at Tilton. Belemnites are abundant 
near the base of the stone, also Rhyntfionella tetrahedra, Terebratula 
punctata, and Pecten cequivalvis. 
On the high-ground south of Eastwell the Marlstone has been 
extensively worked. Iu is a brown friable and sandy ironstone, 
largely composed of tiny organic fragments that have been con- 
verted into iron- ore ; it is oolitic in places, but otherwise much 
resembles the Norfolk Oarstone. Fissile sandy beds occur below 
the ironstone, and they were to be seen in a cutting by the incline ; 
while near its base, the rock contains ochreous and phosphatic con- 
cretions, that give the bed a conglomeratic appearance. Below, 
about 20 feet of bluish-grey sandy and micaceous clays with 
indurated bands, were exposed.* 
At Woolsthorpa the beds that are worked, consist of about 
8 feet of brown sandy ironstone, with hard greenish cores in 
places, but very changeable in character. Ammonites spinatus, 
Avicula incequivalvis, Terebratula punctata, and Rhynchonella 
tetrahedra occur. The beds for 6 or 6 feet, become more 
calcareous, below and in some places more nodular and sandy, 
and too poor to be used for smelting. The Marlstone rests on 
grey laminated shaly clays with ironstone-nodules and sandy layers, 
about 6 feet of which were exposed. 
At Wookthorpe and Eastwell the profitable beds are roughly 
separated from the unprofitable, by a layer of hard ferruginous 
and sandy limestone, crowded with specimens of Rhynchonella 
and Terebratula. These fossils are by no means confined to this 
horizon, but they are conspicuously developed in this hard bed, 
which is much charged with green earthy matter. 
Near Grantham the Marlstone attains a thickness of about 27 
feet, and the total thickness of the Middle Lias, judging by the 
observations of Mr. W. H. Holloway, is about 150 feet.t 
The beds immediately below the Marlstone were exposed in a 
brickyard in Barrowby Lane w r est of Grantham ; they comprise 
about 30 feet of grey and brown sandy and micaceous shales, with 
layers of sand, sandstone, and ferruginous limestone, the whole 
resting on a floor of septaria. 
* See E. Wilson, The Lias Marlstone of Leicestershire, Midland Naturalist, 
vol. viii. (reprinted). 
| Jukes-Browne, Geol. S.VV. Lincolnshire, p. 143. 
