VOL. XV.(1) THE PRESIDENT’S ADDRESS 13 
to the Lower Cambrian quartzite of the Wrekin. The 
base of this series shows included fragments of altered 
purple and green felspathic breccias and shales, and similar 
rocks have been detected in place below the quartzite 
at Barnt Green. In the Nuneaton district, certain strata 
mapped as Carboniferous turn out to be Cambrian, and at 
their base reappears the quartzite with derived volcanic 
fragments. The volcanic rocks, consisting of ashes and 
felsite, emerge from below the quartzite at Caldecote. 
The ash-beds are made up of angular bits of quartz 
and felspar, sometimes of the minuteness of dust. The 
eruptive rock is a quartz-felsite, but whether intrusive or 
a contemporaneous lava has not been determined. 
The most important mass of Precambrian volcanic rocks 
in the eastern Midlands forms the picturesque region 
of Charnwood Forest. The local name “ Charnian” has 
been given to the series; but it is generally admitted that 
they are the equivalent, at least partially, of the Uriconian. 
Their volcanic origin is most marked. Conspicuous 
varieties are green slates, sometimes so well cleaved as to 
be used for roofing. They are composed of comminuted 
felspar crystals, with earthy matter and some lapilli, and 
sometimes contain epidote or viridite, which gives the 
green colour. Some kinds are coarser, and these grade 
into breccias, containing angular fragments of slate, to- 
gether with lapilli of andesite, trachyte, and other eruptive 
rocks. 
The granite and syenite of Charnwood are well known 
for their commercial uses. They are regarded as intrusive 
in the volcanic series, and are therefore of later date. 
I know of no other Uriconian masses in Great Britain ; 
but in the north-west of Scotland evidence has been ob- 
tained of the former existence of a Precambrian volcanic 
formation which has entirely vanished. The red sandstone 
of Loch Torridon, considered by McCulloch to be Old Red, 
