ES eee 
GEOLOGY 17 
II. 
GEOLOGY 
BY 
H. H. GREGORY, M.A., 
ASSISTANT CURATOR, LEICESTER MUSEUM AND ART GALLERY. 
Position of the Area—Chief Rock Formations—Charnwood Forest Rocks— 
Granitic Rocks—Mountsorrel Granite—Carboniferous Limestone—Millstone 
Grit—The Coal Measures—The Triassic Rocks—Rhetic Beds—The Lower 
Lias—The Middle Lias—The Marlstone Escarpment—Ironstone at Tilton— 
The Upper Lias—Inferior Oolite—Glacial Drift and River Deposits—The 
Quarrying Industry. 
LEICESTERSHIRE can claim much of interest in the diversity of its general 
geology. Situated as it is in the Midlands of England, it forms part of 
the wide central plateau which is composed of Triassic and Jurassic 
rocks, It lies to the south of the southern termination of the Pennine 
axis, around which sweeps the plain of Triassic rocks on both the east 
and the west. ‘Two narrower arms of this central plain bifurcate from 
the area and continue northwards. On the eastern margin of the Trias 
the Jurassic rocks form prominent scarp features. The line separating 
the Triassic and Jurassic rocks runs across the irregularly pentagonal- 
shaped county of Leicestershire from a point about two miles west of 
Lutterworth in a N.N.E. direction, through Dunton Bassett and Wigston, 
passing east of the city of Leicester to Brooksby in the Wreake Valley, 
thence westwards to Sileby and north-north-westerly to Stanford-on- 
Soar, when it continues northwards and north-eastwards into Notting- 
hamshire. 
To the west of this line the Triassic rocks form the major portion of 
the solid floor of the surface of the county through which appear the 
older rocks, for which Leicestershire is so justly famed, while to the 
east of the line the lower and middle Jurassic rocks (Lias and Oolite) 
rise. in escarpments, whose scarps, where prominent, face westwards. 
A variety of resulting physical features and land forms within this area 
is therefore not surprising. 
Were the superficial deposits (glacial boulder clay, sand and gravel) 
to be removed, the city of Leicester would be seen to be almost centrally 
Situated in the county, nestling as it were in the lea of the Jurassic rocks 
and itself built on the Keuper Marls, but within easy access of each of 
the outcrops of the other geological formations and in a position at the 
navigable head of the river Soar. The river Soar, for much of its 
course, actually skirts the line separating the Triassic and Jurassic rocks. 
The north-eastern lobe of the area culminates in the Belvoir ridge, 
an escarpment composed of Lower and Middle Lias rocks, of which 
B 
