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SLATY CONGLOMERATE. 
ON A SLATY CONGLOMERATE IN THE ROCKS OF 
CHARNWOOD FOREST. 
BY H. E. QUILTER, OF LEICESTER. 
It is no doubt well known tliat tlie rocks of Cliarnwood 
Forest are tlie remains of a volcanic district, consisting chiefly 
of volcanic agglomerates, ashes, and slates. One or two 
of the sections show, interstratified with them, bands of 
pebbles not more than 4 or 5 inches in thickness ; the one 
which I shall refer to and describe is interstratified with 
ashy slate, and is exposed near The Holgates, Bradgate Park. 
Conglomerates, as a rule, are usually interesting from the 
well-known association of physical conditions under which 
they have been formed, but when associated with ashes and 
slates of volcanic origin their interest becomes augmented, 
and the physical conditions under which they have been 
formed are somewhat more complex. 
This conglomerate is mentioned by Messrs. Hill and 
Bonney, in their researches in these Cliarnwood rocks, as 
“ a conglomerate of slaty pebbles with felspatliic fragments.” 
A close examination reveals the fact that this conglomerate 
has been acted upon by the same force or forces that induced 
the cleavage in the slates with which it is interstratified, 
splitting up the pebbles, so that very few are perfect. 
The matrix is a grit, composed mainly of rounded quartz 
grains ; the pebbles are well rolled and waterworn, and range 
in size from 1 to 3 or 4 inches in their longer axis, and 
consist chiefly of quartzose rock, with small crystals of quartz 
about -j 1 ^- of an inch in size scattered throughout. Pebbles 
of jasper are not uncommon; a few are of the rocks of the 
district, one being composed of the pinkish felsite fragments 
so common in the agglomerates of the district, and another 
of coarse pinkish quartzose slate, with embedded angular 
fragments of fine-grained green slate. Messrs. Hill and 
Bonney think that these rocks afford evidence of the existence 
of lakes, into which some of the ashes of the volcanoes fell to 
form slates; and it is evident that water must have had 
something to do in the formation of this conglomerate ; the 
water must also have been in motion, either as tidal action 
m an extensive lake or as running water, to convert the 
rough pieces of rock into rolled pebbles. 
Dr. C. Callaway, in the “Geological Magazine,” 1881, 
gives an instance of conglomerates in some other older rocks 
that were formed by contemporaneous denudation:— “ A 
