66 



THE GEOLOCtIST. 



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-olFerings amongst the weeds, but I- certainly saw nothing of the kind, 

 nor were there any of the larger moUusks so constantly cast up on our 

 beaches. There appears no reason, a 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 shel- 

 tered 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 l-ith, 1861. 



ITortliampfon Sands. 



Dear Sie,— In repl3nng to Dr. T^'^right's communication in the last 

 number of your excellent periodical, I ofl'er linn my apologies. The origin 

 of my mistake was, in carelessly reading tlir.t part of ]\[r. Aveline's ' ]\Ie- 

 moir 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 in- 

 stance, in Ecynolds's ' Geological Atlas,' lately published under the revision 

 of Professor Morris, all the country over which tlie 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. 



Tlie fact is, no one knows exactly where to place or with what to class 

 these sands. Lias the}^ assuredly are not. ]\lr. Aveline considers them 

 to be equivalent to the Stonesfield Slate of Oxfordshire. This seems likely, 



