82 



LIMESTONES, 



Upper 

 Gallery. 



Wall-case 43. 



sand 



i, with imperfect limestones, clays, and marls. At 

 the west corner of the Apley Wood a bed of calcareous sand- 



dina, 



(* 



Un 



norbis, and occasional bones of Turtle) appears on the shore 

 beneath the sea wall, resting on ragstone, similar to that 

 seen at Nettlestone, where it is 10 feet or more in thickness. 

 The shells, which are as much crowded as in Sussex marble 

 (No. 90,) are sometimes filled with a greenish marl, and the 

 rock itself is somewhat ferruginous, and of a pale ochreous 



•logical Map No. 10, and « Survey Memoir 



colour." 



Wi 



Forbes. 



92 and 93 — Headon Hill limestone, earthy middle 



JEocen 



of Planorbis, %c. — Headon Hill, Isle of Wight. 



This limestone attains its greatest development at Headon 

 Hill, from which circumstance it is generally called the 

 Headon Hill limestone. It thins out gradually from the 

 western extremity of the Isle of Wight, towards the north 



and east. (See " Survey Memoir 

 plates 9 and 10, and Geological 15 

 upper Headon series. 



the Isle of Wight," 

 No. 10.) From the 



94. — Purbeck limestone, shelly limestone, principally 

 composed of casts of Cyrena, from the intermarine beds of 



the middle Purbeck. 



Dorset, 



In Dorsetshire, immediately resting on the " cinder bed," 

 No. 173, Case 41, occurs a series of beds, partly of fresh- 

 water, partly of estuary and marine 



origin. 



From this 



circumstance, they have been called the Intermarine 

 series, by Professor Edward Forbes, in his classifica- 

 tion of the Purbeck strata. In Durlston Bay, these beds 

 attain their maximum thickness of 45 feet ; eastward, 

 in common with the great mass of the Purbeck strata, they 

 become much thinner. In the Isle of Purbeck, the Laning 

 Veins, the Royal, Freestone and Downs Veins, the four 

 principal veins quarried, all lie in the Intermarine series. 



Map 



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pn 



In 



0! Q w 



These mi 

 carbonise 



s, In 



l 



1 



98.— Poe 



kamj, T\ 



In the Y 



wliic 



; s:ime the 



with irreffu" 



ml perfect 

 *i are bnr 





