272 
THE GEOLOGIST, 
with these ore-caveras, which are locally termed " churns, ' there 
are some facts deserving special notice. Directly beneath the lowermost 
bed of the stratified rock, termed by the miners the "lidstone," the 
" crease" is traversed by a series of irregular joints or pipes, technically 
termed "leads," which rise out of the "churns," and often penetrate 
into the "lidstone," and even far beyond into the overlying rocks, 
coming out to the day. These " leads," when followed, usually 
increase in width, and then expand at the depth of a few feet — perhaps 
of only a few inches — into the churn-proper. The chums are not isolated 
pockets, but have strings or branches, more or less numerous, likewise 
termed " leads," which communicate with other churns lying either in 
the same plane, or in an inferior or superior one ; hence the search for the 
ore is not of that precarious nature that it would have been had the 
"churns" been solitary, and not connected deposits. Experience has 
proved that the smaller the lead the larger generally is the " churn." 
The growth of the " mine-ground," to use a miner's expression, or the 
mode in which the ore is dispersed in the " churns," much resembles 
the conditions under which crystallized deposits of other minerals, 
such as carbonate of lime and sulphate of barytes, are often found 
in other caverns. The roofs of those churns which lie nearest to the 
lidstone are invariably encrusted with stalactitic ore, the crystallization 
apparently radiating towards the centre of the segments of the circles 
which are described by the irregular rolling form of the roof. In 
the dividing masses of "crease," geodes are exceedingly common, and 
concretions of compact hieniatite, lined with shining crystals of hydrous 
oxide of iron, are constantly detached from near the walls of the 
churns ; the interior of the large churns, however, are mostly filled 
with powdery rod haematite, held together by a slender frame-work of 
crystallized or compact ore, which trills easily before the pick, ren- 
dering the getting very inexpensive. In many of the old workings 
large quantities of the powdery ore or " Smith's Mine," which forms 
by far the richest product of the churns, have been found from time to 
time, having evidently been rejected by the old miners, who were pro- 
bably unable to use it from its choking the furnace in the air bloomeries. 
The dimensions of the churns often exceed the belief of those who have 
not explored them, and few persons travelling over any of the roads 
near Mitcheldean, or from Bream to Lydney and Coleford, in fact, 
over nearly all sides of the Forest near the crop of the limestone, are 
