250 EXCURSION TO FROGHALL, CALDON LOW, AND ALTON. 
into road-metal. The process being similar to that in use in other 
localities, however, it need not be described. Lying about among the 
limestone, were some massive geodes, where the prisms of calcite were 
four or five inches long; and although very interesting as mineralogical 
specimens, they seemed to be regarded as refuse here. A fine red clay, 
brought dowa in large quantities in the trucks from the limestone 
quarry, was evidently of some commercial value, for the women as well 
as men connected with the canal boats were actively engaged in taking a 
cargo of it on board. It somewhat puzzled us to know what formation it 
could have been derived from. Among other things we learnt here that 
the limestone, of which there were such stores all round, contained too 
much iron to be useful for agriculture, but that it made the best of 
fluxes for smelting. 
Taking our seats in a specially prepared tram-wagon, we soon found 
ourselves gliding, without any visible motive power, up a gentle incline 
cut through the dark gray shales of the Lower Coal Measures. Mean- 
while the curtain of dark clouds and haze which had hitherto given an 
air of cold solemnity to the excursion now swept swiftly across the sky, 
and with bright sunshine and the bluest of blue skies overhead, and 
amid charming scenery, almost romantic, we were presently making our 
way along one of the spurs of high ground that stretch from the Weaver 
Hills down to Froghall. 
We ‘pulled up” at Oldridge to examine a curious pillar, or 
“needle,” of what seemed to be the Third Grit (of the Survey) resting on 
the shoulder of the ridge along which the tramway passed. The ground 
around was smooth and grass-grown, sloping rather steeply into an east- 
and-west valley, which widened out to the west. The ‘“ needle” itself 
was about 25ft. high, in some parts being as perpendicular as if it had 
been chiselled by hand, and about 12ft. in diameter. It consisted of 
reddish-brown grit with quartz pebbles, and showed distinct oblique 
lamination, in one face inclined at 45° to south-west. It was difficult, 
even on the spot, to come to any fair conclusion as to the exact process 
by which the pillar got formed, for there was no exposure near with 
which to compare it, and time was too short to examine the hill around. 
We know, however, that the Third Grit is usually massive and well- 
jointed, and the fine edges formed by its outcrop are among the most 
noticeable features in the scenery of this part of Staffordshire. It 
may be inferred, then, that this columnar mass represents the ruins of 
an ancient ‘‘edge” or cliff, produced partly by the scooping out of the 
east-and-west valley—the lower part of which is probably in the Yoredale 
formation—and partly due to the physical structure of the grit of which 
it is composed. Similar pillars are met with at Belmont Chapel on the 
north side of the Cheadle coalfield. 
Partly owing to faults and partly to the general outcrop of older 
rocks going west, the sections exposed by the line revealed a complex 
alternation of Yoredale rocks, Millstone Grit, and Carboniferous Lime- 
stone, and at one point we passed through a tunnel in the Yoredale 
rocks, 500 yards long. We were soon in sight of Caldon Low, a flattened 
mound of limestone on the western edge of the Weaver Hills, which rose 
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