24 SCIENTIFIC SURVEY OF LEICESTER AND DISTRICT 
In the working of the ironstones, the Lincolnshire Limestone, where 
suitable, is worked for its lime content in smelting. Much new activity, 
however, is anticipated in the neighbouring district around Corby, where 
these beds are to be worked more extensively. 
GLactIAL DrirT AND RIVER DEPOSITS. 
Later Secondary and Tertiary rocks are not represented in the district. 
The major topographical features had been determined by the end of 
Tertiary time. All the minor features, however, owe their origin to 
the presence of the glacial deposits which obscure the pre-glacial 
topography of large areas of the whole district. The glacial deposits 
are essentially diverse in character, and consist of beds of older sand and 
gravel and older boulder-clay with quartzose sand interbedded and 
succeeded by chalky boulder-clay and valley drift. 
These drift deposits appear to be of two distinct ages, one containing 
quartzite pebbles being derived from the west and north, and the other 
containing chalk, lias limestone and oolite from the east. Possibly a 
third series, found only at lower levels in the valleys and consisting of 
clays and gravels, were deposited at a later date, after the existing valleys 
had taken their primeval form. 
By far the major portion of Leicestershire is drained by the river 
Soar and its tributary, the Wreake. The Soar is a strike stream, having 
cut its valley in a sigmoid curve in Triassic marls at the foot of the 
Jurassic scarps. It is probable that its present course approximates to 
its pre-glacial course. The retreat of the ice-sheet left the country 
strewn with thick masses of glacial detritus which, as one vast sheet, 
rose gradually to the watershed and fell away gradually on either side. 
At Six Hills it is over 120 ft. thick, while in a recent boring for water, 
on the outskirts of Leicester 70 ft. of boulder-clay was proved. Through 
this sheet the rivers and streams have re-excavated their channels, 
often exposing the solid strata below. The numerous brooks draining 
to the Soar on its right bank, north of Leicester, flow down the scarps 
of the Jurassic rocks into which they have eaten their head-waters, while 
the Wreake has collected numerous obsequent or scarp streams and 
joined the Soar as a stream, running along the strike of a projecting spur 
of these Jurassic rocks. Other interesting examples of stream abnor- 
malities can be seen at the Brand and at Ulverscroft Mill, on Charn- 
wood Forest, and also at Croft in the upper reaches of the river Soar. 
After the final retreat of the ice-sheet, the rivers flowed at a higher 
level with greatly increased volume, depositing along their courses much 
sorted sand and gravel, which at the present day remain as river-terraces 
along their banks. Teeth, tusks, and skeletal bones of extinct animals, 
such as the mammoth, woolly rhinoceros, reindeer, bison, and others, are 
found in these terraces. 
These deposits yield valuable supplies af sand and gravel, and a 
thriving industry has grown up with the ever-increasing demand. 
Recently at Quorn and Barkby Holt extensive works have been opened 
for the working of these gravels. 
The Leicestershire quarrying industry has long held a premier position 
