EXCURSION TO FROGHALL, CALDON LOW, AND ALTON. 251 
in graceful treeless but grassy swells from the sterile-looking stretch of 
Yoredale shales. The limestone quarry is about 500 yards long and 
140ft. high ; and we learnt that there was a similar quarry on the other 
side of the hill. Gunpowder is preferred here to dynamite for bringing 
down the rock on account of its greater economy, dynamite being too 
swift and not lifting so efficiently. We had a good opportunity of 
observing the action of gunpowder, as several ‘‘ shots”? were fired while 
we were examining the limestone and the curious veins of calespar 
which traverse it in every direction. It had been arranged, however, 
that an unusually heavy shot should be prepared against our visit; so 
we devoted the time still required to complete its preparation to 
examining the crescent-shaped quarry. At the south-eastern horn of 
the quarry there was what appeared to be a fault, bearing N.N.E., 
and the space between the walls of the fissure (about Sit.) was 
filled with subangular pieces of limestone coated with radiate prisms of 
calespar half an inch long, and also contained hematite; the whole 
being imbedded in red clay cemented by carbonate of lime—the same 
red clay, in fact, as we had seen earlier in the day at the wharf, 
Everything being ready for the great shot, we took up position among 
the rocks at the other end of the cliff, whence the cavern containing the 
powder could be seen, about 400 yards off. Highteen hundredweight of 
powder was used for the charge, and it exploded with a stupendous 
reverberating roar, lasting about ten seconds, and accompanied by the 
rattle of thousands of tons of rock as a large area of the cliff crumbled 
down into the quarry. 
Behind the rocks on which we stood was a gap, or “pocket,” in the 
cliff, about 30ft. deep, andas many wide, reminding one of an abandoned 
lode working. It was an old disused clay pit, and once contained one of 
those remarkable deposits of white clay and sand which have been 
observed in several spots on the Weaver Hills, in Wales, and in Iveland.* 
Mr. Binney, F.R.S., who saw the ‘“ pocket” in its best days, says it was 
filled with bluish-white and pink clay, with various coloured sands, and 
strings of quartz pebbles, in lenticular alternations, curving inwards 
towards the middle. The middle of the deposit was occupied by a 
vertical bed or ‘“‘ pipe” of rounded pieces of grit and white quartz pebbles, 
mixed with sand, about 5ft. wide; and Mr. Binney regards this as 
proof that the ‘ whole of the clay and sand now found in the hollow of 
the limestone was the débris of the Millstone Grit formerly lying above 
them,” though he quaintly adds, that “there must have been some 
strange commotion to account for the position of the pebbles.” There 
was little to be seen of the clay now, however, as the middle of the 
deposit had been scooped out, and the Drift capping from above had 
almost completely obscured what remained. One of us here chanced to 
pick up a boulder of greenstone in the Drift. It most resembled one of 
the Derbyshire “ toadstones,” though it could scarcely have become so 
well rounded during the Glacial Period, and was most likely washed out 
of the Millstone Grit, during which period it was probably broken off its 
parent rock, and worn into a boulder. We saw no fossils here. 
* See papers by Mr. G. Maw, F.G.S., “ Geological Magazine,” 1866, 
