444 EOCENE. 



Economic products, etc., of the Lotvcr Bagshot Beds. 



The lignite or brown-coal of Bovey Tracey, which has been used extensively for 

 fuel, is very little employed now, as it gives off a sulphurous smell wlien burning. 

 It has been employed in the pottery at Bovey Tracey. Iron-pyrites is abundant in 

 the lignite-beds, and from its presence spontaneous combustion sometimes takes 

 place after heavy rain in the refuse-heaps. 



The Bovey Beds yield excellent pipe and potter's-clay. The best clay is shipped 

 at Teignmouth, whence it is sometimes termed ' Teignmouth Clay.' According 

 to Mr. Hunt's Statistics above 42,000 tons were sent from the port of Teignmouth 

 in 1865. The mode of raising the clay is extremely simple — the gravel ' head ' is 

 removed, and a large rectangular pit is sunk, which is supported by wood. The 

 workmen cut out the clay in cubical lumps weighing about 30 lbs. each, and fling 

 them from stage to stage by means of a pointed staff ; it is then carried to the clay 

 cellars, and when properly dried sent to the potters. The clays are employed for 

 whitening stones, etc. ; they have also been used in the manufacture of alum. 



An analysis of the clay, recorded by Mr. C. D. Blake, showed the following 

 composition : — 



Silica 47 'o 



Alumina 48 'o 



Oxide of iron I -5 



Magnesia 2 "O 



Water and Waste 1-5 



Although the clays maintain their purity, the proportions of silica and alumina 

 are subject to great variation.^ 



Stiff unctuous white clay, about 80 feet thick, has been worked at Petrockstow, 

 between Torrington and Hatherleigh, in Devonshire, and this deposit, which 

 contains seams of lignite, may, in Mr. Ussher's opinion, be of the age of the Bovey 

 Tracey Beds.' The deposits of China clay in Cornwall will be described in the 

 sequel. 



White clays, etc. (of uncertain age, but possibly Eocene or Pliocene), have been 

 noticed in pockets of the Carboniferous Limestone, etc., near Mold, Oswestry, 

 Llandudno, in Staffordshire,^ and also at Stacpole Court, in Pembrokeshire.^ 



The Poole Clay, so called from its being shipped at Poole, comprises beds of 

 pipe- and potter's-clay, which were worked by the Romans. It is now dug between 

 Wareham and Corfe, at Creech Grange, Nordon, Matcham and Rempstone ;5 also at 

 Branksea Island and Parkstone near Poole; and it is manufactured into ornamental 

 tiles, tesselated pavements, tobacco pipes, etc. (See Fig. 75.) In the Isle of Wight 

 this pipe-clay is almost entirely replaced by sands. Alum was formerly manu- 

 factured in the Island from the clays of Alum Bay, and as early as 1579 at works 

 in Parkhurst Forest.^ Lignite from Nordon, near Corfe Castle, has locally been 

 used as fuel. 



The Agglestone (or Haggerstone), near Studland, is an irregular weathered 

 remnant of Bagshot Sands about 18 feet high, which stands on the summit of a 



1 G. Maw, Q. J. xxiii. 391 ; T. Reeks and F. W. Rudler, Cat. British Pottery 

 and Porcelain, Mus. Pract. Geol., ed. 3, p. 2S1. 



'■^ Trans. Devon Assoc. 1879. 



3 G. Maw, G. Mag. 1S65, p. 200, 1867, p. 250 ; D. C. Davies, P. Geol. 

 Assoc, iv. 423 ; D. Mackintosh, G. Mag. 1874, p. 67 j see also P. B. Brodie, 

 Ibid. 1866, p. 432. 



* Murchison, Silurian System, p. 529. 



s W. H. Hudleston, P. Geol. Assoc, vii. 378. 



* Bristow, Geol. I. of Wight, p. 107. 



