232 Correspondence. 
Mr. Fisher says, ‘ That there must be a vacuity somewhere beneath, 
the subsidence is clear. That it should be in the gravel is im- 
possible, because the stratification, as exposed in the sides of the 
hole for about 10 feet, is perfectly regular; that it exists in the 
London Clay is also impossible ; but that such a cavity should exist 
in the Chalk is probable.” Now I would wish to question Mr. 
Fisher’s explanation with all humility, as I am but a very young 
hand at Geology. 
The author of the article then proceeds to state, that wells 
have been bored in the neighbourhood, at distances of a mile or 
more from the pit; and he continues, ‘I conceive, then, that the 
motion of the water in this subterranean reservoir’ (in the chalk at 
a depth of nearly 300 feet), ‘caused by the draught of water at these 
wells, disturbed the equilibrium of the roofing of the chasm at a 
point where it was barely stable, and caused the subsidence in 
question.’ I would suggest, if the cavity at this depth were large, 
why did not a larger area subside ?—and, if small, surely it would 
not cause a roof of from 200 to 300 feet thick to sink. ‘The expla- 
nation that I would suggest, would rather be, that erosion has taken 
place in the Low-level-gravel at a small depth below the pit, say 
20 feet or a little more (allowing an inequality in the thickness 
of the bed of gravel, which at the well a mile distant was found to 
be abcut 12 feet), and that, when this erosive action had sufficiently 
undermined, the roof fell in. 
I might better explain my ideas by the following section (hypo- 
thetical). 
River Colne. 
} 
j 
i 
\ 
| 
1 
1 
Fig. 2.—Diagram to explain the Formation of the Pit. 
A. Low-level-gravel. Gs Dotted lines to show successive stages of erosion. 
B. London Clay. d. Point at which the débris would (and did) stand highest. 
The erosion would have been either from water from the River 
Colne, or from rain having percolated the gravel and run down 
an inclined surface of the clay at its junction with the gravel.— 
Yours, &c., FRANK RUTLEY. 
13, DenpicH Pxacz, S.W. 
THE BURNING WELL AT BROSELEY. 
To_the Editor of the GnoLoGicaL MAGAZINE. 
Sir —As I did not perceive any reply in the last Number of the 
GEOLOGICAL MAGAZINE to the enquiry in the previous Number rela- 
tive to the Burning Well at Broseley, mentioned in some old topo- 
