152 UPPER, OR FLINTY CHALK. 



sisting of pebbles and fragments of chalk, held together by a ferruginous 

 cement. A portion of the pit in which sections of three of these wells 

 occur, is represented Tab. iv. fig. 3. An appearance somewhat analogous 

 is observable on the north side of the chalk-hiU on which the church of 

 St. John, sub Castro, in Lewes, is situate *. The broken chalk in Falmer 

 pit is in very small pieces, the angles of which are perfect ; a proof that 

 although minutely divided, it has not suffered by attrition. The sides of 

 the vaUies of the South Downs, are universally composed of chalk, of a 

 character precisely similar ; an appearance, which in all probability, has 

 resulted from the ruin of the chalk cliffs having accumulated in sloping 

 taluses at their base. 



Brighton pits. There are several chalk-quarries in the vicinity of 

 this celebrated watering-place, but of these, one only is particularly worthy 

 of notice f. The pit alluded to is situated near the church, and affords an 

 excellent example of that fractured state of the chalk, which has been pre- 

 viously mentioned. It is thus described by Sir H. Englefield : " The 

 upper part of this chalk is in separate masses, not perfectly rubble, but 

 with aU their tender angles sharp, exactly as if just broken to pieces to 

 put into the lime-kiln, and quite clean, nearly of a size, and almost with- 

 out any chalk powder mixed with them." Some remarkable veins of 

 shattered flints occur in this quarry iji. 



Preston. The quarry is extensive, and hes immediately behind the 

 village ; it formerly produced numerous remains of fishes, palates, teeth, 

 &c. but is now seldom worked. It is however deserving of attention, on 

 account of several thin veins of pure flint that fill up vertical fissures in 

 the chalk, and which, to use the language of Sir H. Englefield, " appear 

 exactly as if the flint, not being quite hard when the fissures took place, 



* A circumstance somewhat similar is mentioned by M. M. Cuvier et Brongniart. These 

 naturalists remark, that in the beds of the lower marine formation, and particularly in those of 

 Liancourt, natural wells of considerable size are sometimes found, filled with ferruginous and 

 sandy clay, and waterworn siliceous pebbles. Geolog. Trans. Vol. ii. p. 208. 



■\ This chalk is very pure ; a specimen of the specific gravity 2'34, analyzed by my brother, 

 was composed of. Carbonic acid 43*4 



Lime - - 56"0 

 Silica - - 0"6 

 J Linnean Transactions, Vol. vi. p. 108. 



