REPORTS. 
xlix 
" A numerical census shows that flints of various kinds formed 
40 per cent, of the deposit; schorl rock, 13 per cent. ; limestones, 
10 per cent. ; grits and quartzites, 10 per cent., the grits being to 
the quartzites as two to one ; quartz pebbles, 9 per cent. ; slate, 2 
per cent. ; chert, 2 per cent. ; lydian stone, quartz schist, and 
hornblende schist, each one example. All these rocks occur in the 
county. The limestones include a Liassic, a Cretaceous, and a 
cherty Carboniferous pebble — the nearest existing points for the 
two former being the east of Devon, and for the third the north 
of Dartmoor. 
"Kocks of direct igneous origin muster 13 per cent. There are 
six examples of granitoid rocks (elvans, pegmatite, and schorla- 
ceous granite, but not one a typical granite) ; Devonian lavas ; 
diabase, resembling that of Estover ; gabbro or epidiorite ; and 
Triassic trap — all at present represented in the district. 
" The other rocks of the igneous series are wholly new to us in 
Devon. First in importance are two examples of typical andesite 
— one a hypersthene-andesite, and the other an augite-andesite, 
closely resembling the rocks of the Andes ; and then we have a 
red-brown volcanic conglomerate, mainly composed of andesitic 
fragments, suggested by Professor Bonney to be the result of the 
denudation of volcanic cones \ and several examples of greatly 
altered volcanic breccias or tuffs, now highly siliceous green 
pebbles. The rocks of this last group might well have come from 
the long-vanished volcanic superstructure of Dartmoor, and indeed 
there is no other local source to which they can be assigned. 
"The presumption that they did so is strengthened by the 
important fact that during the past year your Curator has found 
distinct volcanic rocks on Dartmoor, with a volcanic breccia at 
Lee Moor, which includes rock fragments of the same andesitic 
type, and shows flow-structure in a felsitic matrix." 
