VOL. XVII. (i) EXCURSION— STONESFIELD 29 



then the river-valleys have become broadened and deepened, and the patches 

 of Northern Drift proportionately more and more widely separated ; while 

 four terraces of gravel, at successively lower levels, mark the stages in 

 the lowering of the valleys. The information possessed with regard to 

 the Superficial Deposits may thus be summarized : — ' 



Alluvium. — Recent deposits of fine silt, forming flat meadow lands, liable to floods, along- 

 side the rivers. 



River-Gravels. — I. Low Level Gravels. 



(i) ist Terrace: 5 to 10 feet above flood level, and about 220 feet above sea- 

 level. Occurs in isolated patches. (2) 2nd Terrace : 20 to 30 feet above 

 flood-level. O.xford, and most of the villages of the Upper Thames Valley 

 built upon it. (3) 3rd Terrace : 40 to 50 feet above flood-level. At 

 Wolvercote, the lowest layer is rich in Palaeolithic implements of the 

 Chell^en Stage. 



N.B. — All three terraces contain palceolithic implements, and mammoth 

 and other remains. 



II. High Level Gravel. 



(4) 4th Terrace: 70 to 100 feet above flood-level, and, at the Handboroughs, 

 from 300 to 330 feet above sea-level. No fossil remains yet recorded. 



N.B. — The river-gravels " consist of pebbles and small pieces of 

 limestone from the Oolitic [uplands, together with a variable 

 quantity of quartzose and flinty tnaterial, probably washed out 

 of the Glacial {or Northern'] drift." 



Plateau Gravel From 100 feet and upwards above the present level of the river, and of 

 or very similar constitution to such Northern Drift in the Lower Severn 



Northern Drift Valley as caps Sandhurst Hill, near Gloucester. The top of this hill 



is 283 feet above sea-level. 



From Handborough the party proceeded to Stonesfield via Combe. Just 

 before entering Stonesfield, a deep " solution valley " 2 was pointed out, and 

 then the Members proceeded to the banks of the Evenlode, south of the 

 village, where typical Clypeus-Grit is clearly exposed. This is one of the 

 prettiest spots in the district, and is of interest both to the geologist and 

 to the student of river-features. Next, the Stonesfield Slate (or better 

 "stone-tile") working was visited. In former years the fissile limestones 

 ihat occur near the base of the Great Oolite were very extensively worked, 

 but now only one pit is open. The shaft down to the slate-bed is about 

 30 feet deep, and then the slate is worked by means of a long gallery. The 

 slate-rock is brought to the surface and left to weather for a considerable 

 time, after which it can be readily split (see PI. VI., figs, i and 2). A num- 

 ber of the characteristic fossils were obtained from the slate-workers. 



Concei-ning the rocks between the Clypeus-Grit and the Cornbrash in 

 North Oxfordshire, Mr Richardson said that much work had been accom- 

 plished of late years on the lower portion by Mr E. A. Walford, F.G.S. His 

 results were most valuable ("On some New Oolitic Strata in North Oxford- 

 shire," Buckingham, 1906), and were worthy of a wider circulation than the 

 form of publication would probably allow. 



In descending order, the beds from the Cornbrash to the Clypeus-Grit 

 are : the Cornbrash, Forest Marble, Great Oolite proper (with the Stonesfield 

 Slate at the base), Neaeran Beds, Chipping Norton Limestone, Trigonia- 

 signala-Beds and Clypeus-Grit. Of these, the last is of Tniellei and Sclilcen- 

 bachi hemerae : the Chipping Norton Limestone of probably fusees ; while 

 Ammonites subcontractus has been found in the neighbourhood, and brings 

 the deposit in which it occurred into line with the Weatherstonc and Shell- 

 Beds of Minchinhampton, and with the Fullers' Earth Rock of parts of 

 Somerset and Dorset. In these parts of Somerset and Dorset, the deposit 



1 A full description of the gravels of the district, by R. I. Pocock, will be found in the Mem. 

 Geol. Surv., " The Geology of the Country around Oxford" (1908), [price 2s 3d], pp. 81-105. 



2 See paper by the Rev. E. C. Spicer, Quart. Joum. Geol. Soc. vol. Ixiv. (1908), pp. 335-342, 

 and pis. xxxviii. and xxxix. 



