THE FETRIFIED FOREST. 395 



limestone immediately above the clay, contain 

 nodules and veins of flint and chert, like those at 

 Durlstone Head ; the middle group is full of 

 trigonise, terebrae, cythereae, ammonites, and 

 other characteristic marine shells of the oolite ; 

 and the upper series, to within twenty feet of the 

 surface, consists of the fine architectural stone 

 which is locally termed the white-bed. Upon 

 this are three or four feet of limestone, full of 

 cavities left by a layer of shells, of which the casts 

 only remain ; and above, is an irregular bed of 

 flint nodules, covered by a thin stratum of earthy 

 oolitic detritus. Beautiful yellow sulphate of 

 barytes, called sugar-candy -spar, and stalactites of 

 calcareous spar, occur in the fissures of the lime- 

 stone. 



The petrified forest.— Upon the uppermost 

 oolitic stratum, is a layer a foot thick, of very dark 

 brown friable loam, which appears to have been a 

 bed of vegetable mould. It contains a large propor- 

 tion of earthy lignite, and like the modern soil on 

 the surface of the Island, waterworn stones, and 

 pebbles. This layer is called the " dirt-bed" by 

 the quarry men, and in and upon it are stems and 

 branches of coniferous trees, and plants allied to 

 the Gi/cas and Zamia. Many of the trees and plants 

 are standing erect, as if petrified while growing 



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