100 
Now Mr. Tiddeman describes this upper clay or cave 
earth as gradually thickening from the entrance towards the 
rear of the cave, and he places a laminated clay between it 
and the lower cave earth, which he also describes as dipping 
gradually from the entrance towards the rear of the cavern, 
and he distinctly pronounces this laminated structure to be 
evidence of its glacial origin, and he supposes it to have been 
deposited in the following manner : — 
“ Let us imagine a glacier or an ice sheet passing by the 
mouth of the cave and partly blocking the entrance with its 
rubbish * * * * the glacier melts by day and usually 
(though not always) freezes by night. The moraine rubbish 
hinders the coarser debris from entering the cave, but gives 
passage to glacier water charged with fine mud. The glacier 
by its grinding keeps the water charged with mud, and the 
frequent change from daily flow to nightly inaction, gives 
rise to that close lamination, which is its characteristic 
feature.” 
With all respect to the opinion of so high an authority, I 
altogether deny the possibility of this being the true expla- 
nation, for the following reasons : — 
(a) Glaciers do not deposit fine mud in lateral moraines 
150 or 200 feet above the base of the glacier; and even if 
they did, it is not possible that such mud could flow into 
a cavern closed at its end as here described. 
(b) The laminated clay occurs in the cave on the surface, 
at a 'point where it can only be of most recent origin, near 
the dome which terminates in a “ pot hole,” and by which 
it has evidently been only recently introduced ; and similar 
clays occur in other caverns, ivhere glacial action as above 
described could not have obtained. 
After a most careful examination I am perfectly satisfied 
that Mr. Tiddeman has overrated the importance of this 
laminated clay, and that his theory is altogether erroneous. 
