amongst other things I remember a portion of a tin kettle and a fragment of a basket, of the coarse kind used on board colliers and other ships.
Here, then, is a cavern which the sea is at present filling, and in which it is depositing relics of man and portions of terrestrial mammals, but not, so far as I could discover, any marine organism, excepting the seaweed. Probably a careful search might have detected some small shells and other sea-offerings amongst the weeds, but I certainly saw nothing of the kind, nor were there any of the larger mollusks so constantly cast up on our beaches. There appears no reason, à priori, why some caves belonging to earlier periods may not have received their contents in a similar manner.
Again, those who have visited the Cheddar Cliffs, in Somersetshire, probably remember that a considerable body of water issues from the foot of the right-hand cliff, not far above the village of Cheddar. This stream commences its subterranean journey about two miles off, where it enters a "swallet."
It is scarcely possible to believe that it fails to introduce specimens of the natural history of the district into this cavern, or that it does not deposit organic relics, together with mud and stones, in at least some of the sheltered nooks and recesses which probably occur along its course of fully two miles.
I have no doubt that, at least, one of the celebrated caves of this county was in this way furnished with the materials which have rendered it famous.
I am far from believing that the history of any cavern can be regarded as generally typical. Neither of the agencies above described could have produced the phenomena observed at Orestone, near Plymouth, where, in all probability, the fossils and the materials in which they were inhumed found a passage through an open fissure into the cavernous interior of the limestone.
It would not be safe to generalize from any individual case, whether it be Kent's Hole, Windmill Hill Cave at Brixham, the caverns at Orestone, or a dirty dog on a study hearth-rug.
I am, yours, etc., Wm. Pengelly.
Lamorna, Torquay, December 14th, 1861.
Northampton Sands.
Dear Sir,—In replying to Dr. Wright's communication in the last number of your excellent periodical, I offer him my apologies. The origin of my mistake was, in carelessly reading that part of Mr. Aveline's 'Memoir on the Geological Survey of a part of Northamptonshire,' where he speaks of the confusion that formerly existed with regard to these sands.
These beds have been assigned to the Upper Lias, although not by Dr. Wright, and are so coloured on more than one geological map. For instance, in Reynolds's 'Geological Atlas,' lately published under the revision of Professor Morris, all the country over which the Northampton sands are so well displayed has been coloured, with the Lias, brown, a mistake which should be avoided if a second edition of that neat and otherwise useful little work is contemplated.
The fact is, no one knows exactly where to place or with what to class these sands. Lias they assuredly are not. Mr. Aveline considers them to be equivalent to the Stonesfield Slate of Oxfordshire. This seems likely,
