VOL. XVI. (2) EXCURSION—CHARNWOOD FOREST eel 
These beds were so affected by earth-pressures as to form an 
ellipsoidal dome. This dome was cut across by a fault, and the 
relative levels of the two halves were so disposed that now the 
weather-eaten south-eastern portion only raises its jagged crags above 
the environing Keuper Marls, while the other portion lies buried to 
the north-west. Owing to this periclinal disposition of the beds, each 
subdivision can be traced more or less continuously around the semi- 
ellipse, although faults have greatly interfered with their regularity. 
Into the clastic volcanic rocks, grits, and slates of the Forest, 
three or four types of igneous rocks have been intruded, the chief of 
which are porphyroids and augite-syenites. The former were intruded 
first, for they are crushed and sheared by the main north-west and 
south-east movements ; while the latter are not. Bosses of augite- 
syenite occur at Markfield and elsewhere in the Forest, and further 
afield at Enderby and Croft, where their hard rock-masses, amid the 
softer marls, give rise to noticeable tumulus-like hills. 
The main folding, faulting, and cleaving of the Charnwood-Forest 
deposits, and the intrusion into them of the igneous rocks, appears to 
have taken place in Pre-Cambrian times. But from that date onwards, 
until closing Triassic times, if not somewhat later, the region was 
subjected to denudation. At the present time the majority of the 
rocks are only just being uncovered, and so, as Prof. Watts has 
picturesquely stated, ‘‘ they still present a scarcely altered Triassic 
landscape: to this day many of the summits are as rugged and pre- 
cipitous as when they were mountain-tops overlooking a Triassic 
desert, cr just submerged beneath the waters of a Triassic lake.” 
Dr C. Callaway, at the request of the President, then added some 
remarks, and has furnished the following notes for this report. 
‘*The age of the Charnwood rocks (Charnian) has not been 
determined with certainty. The Geological Survey originally identi- 
fied them with the Cambrian. Messrs Hill and Bonney cautiously 
referred to them as pre-Carboniferous ; but leaned to the opinion that, 
if their Pre-Cambrian age were established, they would probably be 
correlated with the Pebidian of Hicks (Uriconian of Callaway). They 
were struck with the lithological resemblances between the Charn- 
wood series and the Uriconian rocks of Lilleshall Hill, in the Wrekin 
area. I understand that some of the more recent workers are dis- 
posed to refer the Charnian to the age of the Longmyndian, which, it 
must be remembered, was regarded as Cambrian in the time of 
the earlier work of the Geological Survey. 
“I incline to the view that the Charnwood series is Uriconian 
rather than Longmyndian. I was long ago impressed with the close 
lithological affinities between the Charnian and the Lilleshall rocks, 
which are mainly hornstones and slaty beds of volcanic facies. The 
Charnian as a whole is volcanic, the prevailing types being agglomer- 
ates, hornstones, and gritty and slaty beds, built up largely of lapilli 
and felspar. The Uriconian away from Lilleshall Hill is still pre- 
dominantly volcanic, but associated with volcanic slates and grits are 
numerous flows of lava. The Longmyndian, on the other hand, is in 
