Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/171

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been empty spaces, and the other, that they have been filled from above.

I observed the first in the mine of Dolcoath, between Camborne and Redruth, where, at the depth of seventy fathoms below the adit level, that is to say, according to my observations, one hundred and eighty-four feet below the level of the sea, there was found an empty space in the vein of some fathoms in length, and broad in proportion. The walls of it are smooth, which is seldom the case, as these cavities, called by the miners, druses, creaks, or pouches, are almost always lined with crystallisations; Werner observes, that we find these druses in places where the vein is of greatest thickness. It often very distinctly appears that they have been much longer and wider, but that they have been partly filled up by a new substance having been deposited in them.

The second fact, I have alluded to, I observed in a coal—pit at Littry in Normandy, two leagues S.W. of Bayeux. In sinking the pit St. George, there was found in a vein at the depth of two hundred and fifty feet from the surface, a conglomerate formed of rounded pebbles, the greatest part of them flints, although the saalbande and the rock are of stratified limestone. A branch of a tree was also found, with the ligneous structure preserved. Werner mentions