42 
THE SYENITES OF SOUTH LEICESTERSHIRE. 
Nuneaton and Atherstone) we were able to prove some time 
back. Tlie same Cambrian Beds have also been reached in 
two boreholes put down on the east side of Leicester, between 
the Spinney Hills and the village of Evington. In the first 
of these borings hard, much-jointed, bluish slates were reached, 
at a depth of 728 feet, and pierced to a total depth of 819 
feet. In the second boring, a little further east, very similar 
slates were touched at 886 feet, and the boring attained a 
total depth of 1,002 feet. Other borings near Market Bosworth 
have revealed the presence of precisely similar coarse red, 
purple, and blue slates, underlying the coal measures. 
On the whole, it seems probable that all the syenites of 
South Leicestershire are intrusive in rocks of Cambrian age. 
As to the actual date of the intrusion we cannot be certain, 
but it may possibly have taken place during the Lower 
Silurian period, when, as we know, volcanic action was rife 
elsewhere in Britain. 
Economic Uses .—Our modern systems of paving have 
brought into great request rocks possessed of a sufficient 
degree of hardness and toughness to stand the wear and tear 
of our streets. As we stand in any syenite quarry we 
observe the rock to be crossed in two or three directions by 
well-marked cracks and fissures. These are termed master- 
joints , and between them the blocks of stone are again 
divided by minor joints. These joints greatly facilitate the 
working of the rock ; which, indeed, it would be impossible 
to quarry if it were not for their existence. A mass of tough 
boulder-clay, in which there are no joints, is dreaded by a 
navvy far more than the hardest granite. 
In the syenite quarries the first task is the removal of the 
surface soil. Holes are then bored in the rock with iron rods 
to a depth of ten or twenty feet. In these holes charges of 
powder are inserted and fired, by which a large quantity of 
rock is dislodged and made to fall upon the floor of the pit. 
The great blocks are then still further split up by powder or 
by dynamite into masses of a more convenient size. Skilled 
workmen now take the stone in hand, and, by properly 
directed blows with heavy hammers, divide it into square or 
oblong masses (four-inch cubes are most commonly made) 
termed setts, or into longer pieces called kerbs. The smaller 
fragments are broken up and used as macadam. 
The South Leicestershire syenite splits, “ cuts,” or cleaves 
very readily. It is largely used in the neighbouring towns 
and in the eastern counties; many thousands of tons are also 
sent to'London annually. The average price of good setts is 
about twenty-seven shillings per ton. 
