THE GEOLOGIST. 



340 



ironstone is absent, and a tliick 

 covering of drift lies on tile 

 Chalk ; and at sucii a spot as 

 this Mr. Harris made Ms large 

 trench., described in Mr. Prest- 

 wich's paper (p. 332). His 

 smaller trench was dug at a spot 

 (like that at C H), where a rem- 

 nant of the ironstone remained 

 nnder the drift. At H G is a 

 peak of chalk standing high np 

 in the Drift, which may be sup- 

 posed to be thirty feet thick; 

 snch rough pillars of chalk are 

 not uncommonly met with in the 

 excavations which the farmers 

 make in gravel and clay to get 

 chalk for their lands along the 

 back of the IN'orth Downs. 



Mr. Prestwich truly states that 

 it is difS.cult to trace at the sur- 

 face the range of the " Kentish 

 Crag ;" and that it is so the 

 diagram will show. It is but 

 seldom that the ironstone and 

 ironsands are well seen at the 

 sm^face ; they are usually masked 

 by the Drift ; and farther, these 

 are but relics of the original 

 beds ; and it is often difficult to 

 distinguish these, even when ex- 

 posed, from the ferniginous Drift 

 in which they are enveloped. 



It is to be hoped that local 

 observers will follow up Mr. 

 Prestwich's researches, and en- 

 deavour to work out more par- 

 ticulars about these interesting 

 ii^onsands ; and perhaps the ac- 

 companying diagram will serve 

 the pm'pose of connecting toge- 

 ther before the eye the various 

 conditions under Avliich patches 

 of these strata remain on the 

 chalk- surface, and help to direct 

 renewed attention to the subject. 



