682 MB. F. CHAPMAN ON THE BABGATE BEDS OF 8UBBEY. [Nov. 1 894, 



At the lower end of the lane can be seen the yellow sand with 

 ironstone, evidently belonging to the Hythe series, following which 

 are pebbly beds about 12 feet thick, and with these the Bargate 

 series commences. 



The Pebble-bed is replaced higher up by a hard siliceous rock, of 

 a whitish tint variegated with greenish-grey streaks. The rock 

 contains only a trace of calcareous matter, and consists almost 

 entirely of quartz-grains and sponge-spicules (the latter having the 

 axial canals usually filled in with mamraillated chalcedony, though 

 occasionally with glauconite),with a few glauconite-grains (see fig. 1). 



Fig. 1. — Thin section of siliceous rock formed mainly of sponge- 

 spicules {seen in transverse sections'), with glauconite-grains and 

 quartz. Bargate series, Halfpenny Lane, Ohihvorth. x21. 



A softer bed lies upon the hard rock containing sponge-spicules, 

 consisting apparently of brown sandy clay, and showing current- 

 ledding when freshly broken down. This soft bed, upon washing 

 away the clay, yields a plentiful supply of sponge-spicules. These 

 spicule-beds amount to about 8 feet in thickness, and may be a 

 thicker development of the somewhat similar siliceous rock occurring 

 at Littleton (see ante, p. 680). Dr. G. J. Hinde, V.P.G.S., has kindly 



