Reports and Proceedings. 81 
infilling of sand and clay which has yielded so fruitful a harvest 
to the patient researches of the above-named geologist ; here it was 
that he discovered the teeth of Microlestes, the little Mammal allied 
to the Kangaroo-rat of Australia. Leaving Holwell, the Members 
passed by Nunney Castle, and were conducted through the romantic 
valley called ‘Vallis,’ where are a succession of quarries, representing 
the same geological features as at Holwell; the Lias-dykes, how- 
ever, in this locality being in some of the sections only a few 
inches in thickness, and looking more like veins running through 
the limestone than anything else. Several of these sections repre- 
sent the Carboniferous Limestone capped unconformably by the 
Oolite. 
The excursion was terminated with a vote of thanks to Mr. Moore 
for his energetic guidance in this geological labyrinth. 
The next Geological Excursion was on August 11th to Burrington 
Coomb, and across the Mendips to Cheddar Cliffs, by Charter House. 
Mr. W. Boyd Dawkins, F.G.S., kindly undertook the guidance of 
the Members this day; and, having first taken them to the cavern 
on the left of the ascent, explained his views as to the formation of 
_Burrington Coomb, and limestone ravines in general, of which the 
following is an abstract :— 
‘When the Mountain-limestone of the Mendip-range was first 
exposed to atmospheric influences, the rains that descended upon it 
sank into the joints, and, carrying away portions of the rocks in 
solution, formed little streamlets, which gradually united until they 
formed the main stream that flowed through the channel, which is 
now Burrington Coomb. For countless ages it flowed on through a 
large cavern, gradually enlarging its bed, while the entrance through 
which it passed into open day becoming decomposed, and the roof 
falling in atom by atom, the small ravine grew larger and larger, 
and crept upwards at the expense of the cavern, until the latter 
was altogether lost ; and thus, in the course of time, the coombs and 
ravines are formed with which we are all so familiar in Limestone 
districts.’ 
In illustration of his theory of the action of water inside caverns, 
Mr. Dawkins conducted the party, or some at least of those who 
were sufficiently bold to venture, into the intricate windings of the 
great Goat Church Cavern, and there pointed out the gradual pro- 
cess of wearing away which is now going on. In one of the many 
chambers lately excavated by Mr. Dawkins, he showed the spot 
where he discovered a flint flake associated with the tooth of an 
extinct animal. The party, having returned to daylight after an 
hour’s absence in the heart of the limestone rocks, were next taken 
across the Old Red Sandstone axis of the Mendips, to the head 
of the Cheddar Cliffs ; and here, in illustration of the gradual dis- 
integration atom by atom of the outside of the cavern, were shown 
a good specimen of a coomb in process of formation, the roof gra- 
dually falling in stone by stone, and the ravine creeping on and on 
by slow degrees into the cavern, as the latter yielded to the wearing 
process of atmospheric agencies. 
VOL. Ii.—NO. VIII. G 
