250 NOTE ON A RECENTLY FORAIED CONGLOMERATE 



Note on a recently formed Conglomerate near St. Mary's 

 Island, Northumberland 



By David Woolacott, D.Sc, F.G.S. 



(Received December i, 1908) 



A little to the north of St. Mary's Island between tide- 

 marks, and extending out beyond low water, there is exposed 

 at present (November, 1908) about a score of patches, 

 totalling several square yards in extent, of a hard cemented 

 conglomerate a few inches thick. It is firmly attached to 

 the bed-rock, and appears to have been only recently un- 

 covered. As many detached pieces are lying about on 

 the shore, it must be undergoing rapid denudation. It is 

 chiefly composed of grains of sand, sandstone and other 

 pebbles, angular fragments of shale, pieces of green apatite, 

 rivets, bolts, and bits of iron plate, the whole being compactly 

 cemented together, and covered with a thin black glaze. 

 After careful searching by Dr. Smythe, G. Weyman, and myself, 

 there were also found firmly set in the deposit a limpet, some 

 lead shot, a brass nail, a corroded and iridescent halfpenny, 

 crystals of calcite filling up holes, man)'- irregular masses of 

 iron pyrites, and some small perfectly formed crystals of the 

 same material. The heterogeneous layer lies almost entirely 

 on the shale which is noted for having cone-in-cone structure 

 developed in it, and is firmly attached to this bed. It is 

 obviously of quite recent origin, the apatite giving a clue to 

 the time during which it has been forming, and the rivets, 

 bolts, and iron plate to the means whereby it has been 

 cemented. Near the place where it occurs a ship called the 

 Jane Clark, laden with green apatite from Norway, was 

 wrecked on St. Mary's Island about 1890, and thus the con- 

 glomerate with this mineral in it has been produced within 

 the last twenty years. The cementing matter has been 

 largely derived from the corrosion of the pieces of iron 

 occurring in the deposit. Some of the rivets have been 



