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HOLOCENE AJs^D RECENT NON-MARINE MOLLUSCA FROM THE 

 NEIGHBOURHOOD OF PERRANZABULOE. 



By Eev. R. Ashington Bullen, B.A., F.L.S., F.G.S., F.B.A.I. 



Mead 8(h January, 1909. 



The following paper is work which my friend Mr. B. B. Woodward 

 has wanted done for some time past. My opportunity came in 

 JSTovember last, and, had the weather been more favourable, the 

 result would have been probably more important. 



The Church of Perranzabuloe was unearthed by storms in 1835, 

 after being buried by ' blown sand ' for nearly twelve centuries. 

 The place was at once raided for building material and architectural 

 relics, some of which are now in Truro Museum (Royal Institution of 

 Cornwall). The ruins would give a date for anything of the nature 

 of a Holocene deposit, but unfortunately there is none available for 

 examination in the immediate vicinity. There were evidences for 

 kitchen middens near it, as broken marine shells occur at a level 

 200 feet o.n. I found Cardium rmticum and broken fragments of 

 Mytilus edulis near, and there were quantities found in 1835, supposed 

 to be St. Piran's waste-heaps, but probably much older, if other 

 evidences yet to be examined are found to belong to the late Bronze 

 or early Iron age. Most of this shell deposit has been carted off 

 by farmers as a fertilizer. The moss is very thick and wet on the 

 lofty slopes of the hollow in which the ancient church lies, affording 

 a suitable habitat for the species of MoUusca that are most moisture- 

 loving. 



The rediscovered church is about half a mile from the sea-cliffs, 

 from which it is separated by deposits of shell- sand from 50 to 

 probably 70 or 80 feet in depth, although as the sand dunes are 

 deposited on the varying contours of the underlying Lower Devonian 

 rocks, it is somewhat difficult to estimate their depth. 



One of the most interesting points about the work has been the 

 discovery of an old lacustrine deposit in which the MoUusca have 

 been almost entirely of fresh-water species, with the exception of 

 some examples of Helix aspersa and Helicellavirgata, which may mark 

 the former edge of the water, but this is not yet certain ; they seem 

 to have been blown into the water and then sunk to the bottom. 



The shells indicated belong to a deposit formed on the bed of a 

 shallow lake at about 200 o.d., which deposit overlies evenly stratified 

 shell-sand, beneath which lies the slate rock. This stratified shell- 

 sand is about 3 feet above the present surface, where it has been 

 left, but unfortunately much of the deposit with its most valuable 

 shell-evidence has been removed, and only the indurated sand has been 

 left scattered about the site of the lake. This lacustrine deposit 

 underlies part of the dunes of blown sand, which is 40 or 50 feet 

 in thickness hereabout. The stormy wind fortunately scoops out 



