512 Notices of Memoirs — Prof. Boyd-Bmvhins — Iron Ore, Dover. 



TJppEB Cretaceous 



Neocomian 



Oolitic 



IV. — On the Deposit of Iron Ore in the Boring at Shakespeare 

 Cliff, Dover. By Professor Boyd-Dawkins, F.R.S. 



THE general i^esults of the boring at Dover were laid before the 

 British Association at Cardiff in 1892, so far as relates to the 

 discovery of the South-eastern Coal-field. In the present com- 

 mnnication the author treats of a bed of ironstone, which is likely 

 to be of great importance in the new industries which will spring 

 up sooner or later in Kent in consequence of the discovery of Coal 

 in workable quantities. 



The strata penetrated in the boring are as follows : — Feet. 



Lower Gray Chalk and Chalk marl . .130 

 Glauconitic marl ..... 8 

 Gault 121 



! Folkestone Beds 64 

 Sandgate Beds . . . . .77 

 Hythe Beds .87 

 Atherfield Clays ..... 18 



/'Portlandian 32 



I Kimmeridgian ..... 73 



JCorallian 159 



' j Oxfordian\ ,go 



Callovian J * " ' 



VBathonian 156 



Coal-measures with twelve seams of Coal 23 feet 6 inches thick . . 1068J 



The ironstone occurs in the Kimmeridgian part of the section, and 



as shown in the following details : — 



PoRTLANDiAN Beds : — Feet. 



Gray marl with oolitic grains of ferric oxide . . • . . . .2 



Hard gray limestone . . . . . . • • • . ■ 1 



Brown calcareous sandstone ......... 2 



Gray shelly limestone with oolitic grains of ferric oxide . 

 Dark-gray marl .......... 



Hard blue limestone with Littorina ...... 



Brown oolitic ironstone . . . . . . 



Gray limestone .......... 



Dark bituminous clay 8 



Flaggy sandstone ........... 2 



Gray sandy clay • . . 4 



Arenaceous limestone with Cidaris ....... 7 



Dark bituminous shale .......... 27 



Gray nodular limestone 2 



Coralline Oolite with the usual fossils, Pecten vagans, etc. . . .27 



The ironstone presents very singular physical characters. It is 

 composed of small dark-brown shining grains of hydrated oxide of 

 iron like millet seed, embedded in a crystalline base partly of 

 calcium carbonate, and partly of iron carbonate. These grains are 

 oolitic in structure, and are probably the result of the same chemical 

 change by which the calcareous beds of the Inferior Oolite in 

 Lincolnshire have been converted into iron ores. They occur, 

 it will be noted, in several strata above the main bed, 12 feet in 

 thickness in the above section. 



This bed of iron ore is identical with that described by Blake and 

 Hudleston at Abbotsbury in Dorset, where it occurs between the 

 Kimmeridge clay above and the Corallian rocks below. 



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