348 CAMERON : SUBSIDENCES OVER PERMIAN BOUNDARY. 
" the subsidence, when a fall of the roof occurred and water came 
" in, but not in such quantities as to cause alarm. The morning 
" of the accident a stronger pressure than usual was felt, water was 
" seen coming down the heading, and volumes of sand and water 
" soon began to pour into the workings, to the depth of five feet, 
" before the survivors had time to reach the cage, which got so 
" imbedded in the sand, that it was all the engines could do to 
" move it. The sand and water finally rose twenty fathoms in 
u the shaft of the pit, or within five fathoms of the Ell Coal. 
" There had been very heavy rains and the river had been 
higher than usual. The inmates of a house, standing 150 yards 
" from the hole, said, they were roused from their sleep by a 
" tremendous noise, and proceeding to the place from whence it 
" came, found a hole rapidly forming, the sides quickly falling in 
" all round ; sand, stones and gravel came from the sides, and 
" apparently fell into a hole in the centre ; when the sides ceased 
" to fall in, the cavity filled with water, which appeared to come 
" from the sides. The area of surface land sunk was about 6 
" acres. Upwards of 1,000 great trees and hundreds of bundles 
" of straw were thrown into the chasm and immediately swallowed 
" up. The geological formation is stratified sand, gravel, and 
" stones, (the side nearest the river being all stones) such as 
" compose a river's bed. Owing to the continuous rains, this 
" deposit had become so saturated that it broke through to the 
workings below. In course of time a pumping engine was 
" erected, and the cavity pumped dry twice a day; this is stop- 
" ped and the pit is working again ; enormous quantities of sand 
"and gravel had to be taken out of the workings." 
Returning to this district — at Hartlepool the Permian and 
Triassic rocks dip or roll towards each other, indicating a trough 
extending longitudinal^ in the direction of their boundary. If 
more of these rocks could be seen, those now visible might prove 
to belong to beds that slope inwards from all round, as they are 
said to do in the salt districts of Cheshire. There are thick beds 
