GEOLOGY 23 
opencast system is about 12 ft., though in the railway cutting near the 
railway station about 18 ft. of ironstone is exposed, and is underlain by 
sandy shales. 
Further north, around Somerby and Pickwell, the Middle Lias escarp- 
ment becomes free of drift deposits, and the rockbed or ‘ Transition 
bed,’ as it has been called, is well exposed as a flat-topped hill dipping 
gently eastwards and presenting a bold escarpment to the west around 
Burrow-on-the-Hill or Burrough Hill, where it attains a height of 690 ft. 
It is on this flat tableland that an early Romano-British encampment was 
located. 
Over considerable portions of this area the Marlstone has been removed 
for supplying the Holwell Ironworks at Asfordby, near Melton Mowbray, 
with raw material. 
There has recently been much increased activity in quarrying the 
ironstone, and the average annual output in this area is over half a million 
tons. The content of iron varies from about 23 per cent. to 2g per cent. 
Above the Middle Lias in this area and separated from the Marlstone 
‘ Transition bed,’ the upper surface of which shows some pene- 
contemporaneous erosion, are beds of clay with nodular limestone in 
bands and septaria. These are succeeded by the ‘ paper shales’ and 
fish and insect limestones. These beds comprise the Upper Lias in 
this area. They form steep banks, and in quarrying the underlying 
Marlstone by the open-cast system for ironstone these measures form the 
overburden which is removed. 
The Upper Lias outcrop in the north-east is only about a mile wide, 
but on the borders of Rutland, into which county it passes, the width is 
greatly increased, and east of Tilton and Tugby it attains its greatest 
width of outcrop of about six miles. South of the river Welland, near 
Market Harborough, the outcrop again narrows to pass beyond the county 
boundary. 
On the east side of the county, in the neighbourhood of Tilton, outliers 
of Inferior Oolite form the cappings of the highest hills, as at Whatborough 
Hill (755 ft.), Robin-a-Tiptoe (726 ft.), and Barrow Hill, near Lod- 
dington, and at Launde Wood. A larger outlier in the neighbourhood 
of Medbourne and Neville Holt on the north side of the river Welland 
is capped by Lincolnshire Limestone, the upper member of the Inferior 
Oolite. Further north in the neighbourhood of Waltham-on-the-Wolds, 
Stonesby and Croxton Park, is a faulted block of Lincolnshire Limestone, 
a cream-coloured oolitic limestone, detached from the main mass at 
Sproxton, Saltby and Croxton Kerrial. Unlike the bold features usually 
presented in the main mass further east, this outcrop has little effect on 
the relief, only forming a plateau which reaches about 570 ft. at Waltham 
and near Lings Hill, north-west of Croxton Park. 
The Lincolnshire Limestone, which varies from a ragstone or oolite 
to a freestone in different localities, overlies the Northampton Sand. 
In east Leicestershire the Inferior Oolite series comprises the 
Northampton Sand, usually rich in ironstone, passing up into brown 
sands, succeeded by sands and clays of a lighter colour. These beds 
represent the Lower Estuarine series. 
