THE CORALLIAN ROCKS OF ENGLAND. 273 



from the rest of the fauna, and perhaps on the whole incline to 

 French rather than to English types *. 



The Abbotsbury Ironstone. — It has long been known that vast 

 deposits of hydrated ferric oxide associated with silica occur at 

 Abbotsbury ; but their geological position has not been made clear, 

 nor their fossil contents enumerated. The deposit is a very local 

 one, and is contained in a synclinal trough on which the village 

 stands. It is very well exposed in two sections to the north of the 

 main street. The first is in the roadway leading over the hill to 

 GorweU, which is cut into the natural rock ; and the dip to the 

 south being greater than the slope of the road, we meet with the 

 highest beds below, and continually rise into lower ones. It is not, 

 therefore, easy to estimate the total thickness. It is a tolerably 

 uniform deposit as seen in this road, the weathering having ob- 

 literated most of the minor features. In the second section, that 

 in Red Lane (a very appropriate name), the beds are less changed, 

 and we may recognize the following variations in them : — 



Section of Ironstone, Red Lane, Abbotsbury. 



1. Loose ferruginous sand ^ ft. in. 



2. Granular iron- ore, with grains about the size of a millet-seed, and | 



with streaks of ferric hydrate in various directions. Fossils }-20 

 abundant, especially Brachiopoda, as Rhynchonella corallina j 

 and Waldheimia lampas J 



3. Coarse ferruginous suboolitic grits in bard cherty bands with 



numerous Ammonites decipiens 2 6 



4. Yellow weathering sand without fossils 2 



5. Dark green earthy suboolitic rock highly charged with ferrous 



oxide 1 



6. Dark ferruginous sandstones with intercalating variable hard beds, 



with fossils in the form of casts, including Exogyra virgula ... 10 



35 6 

 We are unable in this section to trace the connexion of the beds 

 either upwards or downwards; but we can see that there is no 

 room for any thing above them to dip beneath the Kimmeridge Clay. 

 That these, or at least their equivalents, overlie the Sandsfoot Grits 

 is satisfactorily proved on Linton Hill (see fig. 1), where the cliff 

 formed by the latter is distinctly seen to be continued beneath a 

 small mound, in which is an excavation showing the characters of 

 the ironstone. The clays and sandy beds which intervene between 

 the yellow sands at Sandsfoot and the true Kimmeridge Clay are 

 not seen here ; and the Abbotsbury Ironstone may be, as far as 

 stratigraphy is concerned, on their horizon. But this must be 

 better judged of by their fossils. 



In the ironstone we have found the following : — 



* When we first inspected this Osmington section, the sliding forward of the 

 superincumbent clay had so advanced the upper beds as completely to obseure 

 the reading. The very wet winter of 1876-7 seems to have cleared much of 

 this away. One of us, on visiting the locality in March 1877, had tbe good 

 fortune to find the Ringstead-Bay Section especially clear. The statement, 

 therefore, that there is no Coral Rag whatever in the Weymouth district must 

 be modified. 



Q. J. G. S. No. 130. t 



