644 EEPORT — 1894. 



The following Papers and Report were read : — 



1. Some Points of Special Interest in the Geology of the Neighbourhood 

 of Oxford. By Professor A. H. Green, M.A., F.R.S. 



There are several spots around Oxford the names of which have come to be 

 household words in the literature of geology. 



It is not likely that I can add anything to what has been long known about 

 localities which were favourite haunts of Buckland, Phillips, and other of our 

 feremost geologists. But, as excursions to some of these places have been planned, 

 I hoped it might be serviceable to recall attention to the more important of the 

 specialities of these spots. 



We hope to visit historic Stonesfield. Work will be begun at some brick- and 

 ironstone-pits at Fawler, where the Liassic zones of Ammonites capricornus, 

 A, viargaritatiis. and A. spinatm are well shown. Above these comes an at- 

 tenuated representative of the Upper Lias, not more than 10 feet thick. The 

 basement bed, with its mixture of ammonites elsewhere relegated to separate 

 zones, which has been studied by Mr. Walford, is present. Above the Upper Lias 

 we have the representative of the Inferior Oolite, here reduced to the two bands of 



Chipping Norton Limestone. 

 Clypeus Grit. 



The latter is referred to the Parkinsoni zone, the lower zones of the subformation 

 being here absent.* On the hill above lie the workings in the Stonesfield Slate, 

 with its mixture of terrestrial, fresh water, and marine forms, too well known to 

 need special description. Quarries may afterwards be visited in Great Oolite 

 (Upper Zone), Forest Marble, and Cornbrash, one of which shows a curious case of 

 contemporaneous erosion. 



An excursion over Shotorer will show a succession from the Oxford Clay to 

 the Neocoraian Ironsands. One point of interest here is the little coral reefs of 

 the Corallian Beds, and tlie bank of finely comminuted material, derived from 

 their wear, which adjoins them.^ The Portland Beds are sandy and shingly, and 

 mark the margin of the southern Portlandian sea. 



The Neocomian Ironsands are part of a long strip which runs from Wiltshire, 

 through Oxfordshire and Bedfordshire, to Cambridgeshire and onwards. They 

 are coarse, shingly, very current-bedded, obviously shore deposits. Possibly they 

 were formed in a long strait that connected the northern and southern Neocomian 

 basins. At most of the spots where they yield fossils, these are marine. But it 

 is only natural that, as we go along a coast line where the physical conditions 

 change from place to place, there should be a corresponding change in the 

 character and fossils of the deposits. And it is so here. On a hill adjoining 

 Shotover the Ironsands have long been known to contain fresh-water fossils. 

 We are here facing what was the mouth of a river. At Faringdon, again, the 

 beds depart widely from their normal type. There is no current bedding, indeed 

 very little bedding at all. Their abundant fossils include sponges, most of which 

 are very perfect, and delicate bryozoa but little worn, with scattered specimens 

 of perfect brachiopods, all embedded in a matrix of very finely comminuted 

 organisms. These facts seem to me to point to a tract of still water such as 

 would be found in a sheltered bay. In the deeper water of the centre the fossils 

 would be preserved entire, while over the shallow margins they would be ground 

 small, and the finely comminuted matter swept into the central pit till it was 

 filled up. 



An interesting section occurs in a brick-pit near Culham. It shows — 



3. G ault clay, with a band at the bottom containing sand, pebbles, and rolled 

 fossils derived from the Neocomian Ironsands. 



2. Thin band of earthy limestone ; Kimmeridgian (?) or Portlandian. 



1. Kimmeridge Clay. 



' Walford, Q.J.G.S., xli. (1885), p. 38. 



' Blake and Hudleston, Q.J. G.S., xxxiii. (1877), pp. 308-311. 



