VOL. XVII. (l) 



EXCURSION— STONESFIELD 



31 



" At the outcrop the rock presents a rich ferruginous aspect, but when reached at 

 positions where it has been protected from atmospheric influences, its colour is deep olive 

 green ; and the gradual change may be obser\'ed in blocks newly split. In its latter state, 

 it appears to be oolitic under the lens. 



" The character of the ore, before oxydization, is probably that of carbonate and 

 silicate of iron, the latter imparting the green tinge ; when exposed, it passes into a 

 hydrated peroxide of iron. The quantity of silica is about 12 per cent., and of lime 10 per 

 cent. Phosphoric acid is only present in minute quantity — 055 per cent. From an 

 analysis of nine samples made in the Museum of Practical Geology, the average quantity 

 of metallic iron was found to be about 32 per cent." ' 



The Upper Lias, which has been dug atFawler for brick-making, 2 varies 

 somewhat in thickness, the measurements of investigators varying from 5 to 

 over 16 feet. The section laid bare at the time of the visit of the Geologists' 

 Association in igo8, exhibited 12 feet of Upper-Lias clay, with a thin band 

 of pale earthy ferruginous limestone, containing Upper-Lias fossils, resting 

 directly upon the Marlstone. The ammonites that have been obtained indi- 

 cate that the Upper Lias here corresponds to the lower portion of the Upper 

 Lias as developed near Cheltenham. The higher zones are imrepresented. and 

 when one comes to the Oolite it is found that all its sub-divisions inferior to 

 the Upper Trigonia-Gnt are also lacking. There is a great non-sequence be- 

 tween the Upper Lias and Inferior Oolite here. 



The Inferior Oolite at Fawler is thus broadly divisible ; — 



Approximate thicknesses in 

 ft. ins. 



White oolitic lime-washed lime- 

 stones, with few fossils: 

 {teste Bather) 

 i) Nerincsa-'Bed 



Chipping Norton Limestone. 



seen 



[ 



Clypeus-Grit 



Marly 

 Beds 



{b) Terebratula-Murl 



15 



Rubbly 

 Beds 



Massive 

 Beds 



Upper Trigonia-Gnt (circa) 

 The Conglomerate-Bed has 



c) Impure limestone 



{d) Pkoladomya-Ma.Tl 



(e) Marl with indurated portions. . 

 Limestones, rubbly, coarsely-"! 

 oolitic ; Clypeus Ploti, Lima- • 

 tula gibbosa, etc J 



Limestones, more massive ; 

 usual Clypeus-Grit fossils : 

 average 



a) Conglomerate-Bed 



6 

 level 



average 



very uneven under surface, but 

 oyster-covered and often bored upper surface. It is, there can be little 

 doubt, of Garantianw or early Truellei hemera, and comparable with the 

 Conglomerate-Bed of the Radstock district, and of Maes Knoll, Dundry. The 

 lower part of the Clypeus-Grit is quite typical, both as regards faunal 

 and lithic characters ,- but the marly beds are a more local deposit, and are 

 succeeded by lime"stone called by previous authors the Chipping Norton 

 Limestone. 



The Members then drove into Charlbury and caught the 4.30 p.m. train. 



1 " The Geologist," vol. iii. (i860), pp. 303-304. See also Mem. Geol. Surv., " The Geology of 

 the Country around Woodstock, Oxfordshire" (1859), PP- 10-12; Mem. Geol. Surv., "Jurassic 

 Rocks of Britain," vol. iv. (1894.), pp. 303-306. 



2 A railway-truck load of Upper-Lias clay is sent annually from Charlbury to Nether Stowey, 

 in Somerset, for use in the tannery there. It is obtained from the field in which the wind-mill for 

 pumping purposes is situated. 



