part 1] DEPOSITS AT WOKMS HEATH. 23 



the Chalk before piping commenced. Small pieces of chalk are 

 present in the clay nearest the wall of the pipe, and the cla}^ often 

 shows lamination parallel to the wall and sometimes slickensides 

 with vertical grooves. 



The grey clay between the flints, when washed, yields about 

 67 per cent, of mud. The coarser part of the residue consists of 

 ■a few pieces of chalk and flint more or less coated with manganese, 

 a large amount of earthy manganese concretions; prisms and frag- 

 ments of Inoceramus, more or less silicified ; bones, teeth, and 

 scales of fishes ; small phosphatic concretions ; crinoid ossicles and 

 other remains. The sandy portion consists of flints and fine 

 quartz-grains, the latter measuring mostty between 0*15 and 

 0*25 mm. in diameter. There are also heav}^ minerals, amounting 

 to about 0*005 per cent., apart from the manganese and phosphatic 

 material : they include ilmenite and opaque white grains (leucoxene 

 in part), zircon, staurolite, tourmaline (purple, green, and blue), 

 Tutile, kyanite, hornblende, magnetite, andalusite, and possibly 

 garnet. Where the grey clay was exceptionally thick and black, 

 the phosphatic and calcareous constituents were found to be absent 

 •or very scarce. 



Red Clay-with-Flints. 



The flints are like those in the grey clay, but show little sign of 

 manganese. Thin sharp splinters and flakes are more common 

 than in the gre} r clay. They show the original cortex of the flint, 

 and are not formed from pebbles. The clay is red and ferru- 

 ginous, with occasional small black patches of manganese oxide. 



A sample of the clay between the flints gave, on washing, flint 

 splinters, ferruginous matter, etc., on 30-mesh sieve, 12*7 per cent. ; 

 sand through 30-mesh sieve. 15*2 ; mud, 72*1. The sandy residue 

 consists of quartz and flint, with a few silicified foraminifera, 

 •sponge-spicules, etc. Iron-oxide is abundant, in spheres about 

 1 mm. in diameter and larger irregular pieces. Manganese-oxide 

 is less abundant, and neither carbonate nor phosphate of lime was 

 •seen. 



The heavy residue, freed from iron- and manganese-oxides, 

 amounts to 0*043 per cent. It consists of ilmenite and opaque 

 white grains, zircon, rutile, tourmaline, staurolite, kyanite, anda- 

 lusite, and magnetite. The heavy minerals, and especially rutile 

 and kyanite, are more abundant than in the grey cla} r , probably 

 through admixture with the adjacent sand during subsidence into 

 the pipes. 



Sand and Sandstone. 



The sand which comes between the red clay-with-flints and the 

 pebbles in the pipes is sometimes pale buif or almost white, but 

 more often is stained by iron to some shade of yellow or red. By 

 further addition of iron-oxide it is, in places, cemented into a 



