402 
THE GEOLOGIST. 
abruptly from tlie low ground of the Oxford Clay, and overlooking tlie 
valley of the Isis. In a large quarrv, at Kiogstone Bagpuze, the Upper 
Grit may be observed resting on the Coral E-ag, which in its turn reposes 
on the Lower Grit. At Wheatley, to the north-east of Shotover, these 
beds form an anticlinial, or dome, dipping under the Kimmeridge Clay, in 
every direction from the centre. The Coral Eag, in this neighbourhood, 
contains its usual assemblage of zoophytes and echinoderms. The Kim- 
meridge Clay extends along a band of country following the course of the 
Coral l^ag, and resting upon the southerly slope of the terrace formed by 
that rock. Its organic remains do not offer any important differences from 
those of the Oxford Clay ; indeed, many of them are common to both for- 
mations. The best sections of the Kimmeridge are at Headington, near 
Oxford, and Culham, near Abingdon. The Portland beds extend in a 
narrow band round the Shotover ridge of hills. At Combe Wood, near 
Cuddesden, a small patch of Purbeck beds may be observed resting on the 
Portland Stone. They consist of about four feet of grey marly limestone, 
containing Cypris, Mytilus, and Paludina. At Culham, the Gault and 
Lower Greensand may be observed reposing on a base of Kimmeridge 
Clay. The Gault at this place is a blue laminated clay, with its character- 
istic fossils, Ammonites lautus, A. interruptus, Nucula pectinata, Inoceva- 
mus concentricus, and Plicatula pectenoitles . The Lower Greensand con- 
tains no fossils in the neighbourhood of Oxford, but at Faringdon the re- 
markable gravels of this age are almost entirely composed of sponges, 
bryozoa, and mollusca. The freshwater sands of Shotover have been 
the subjects of essays by several writers, who all agree as to their fresh- 
water origin, but are not so unanimous as to their geological date ; some 
being inclined to regard them as being the equivalent of the Hastings 
Sands, or Wealden beds, and others as an estuarine condition of the Lower 
Greensand. Professor Phillips is of the latter opinion, and it seems to be the 
safer course to regard them as an exceptional condition of the Greensand. 
They contain very few fossils ; those that have been collected belong to the 
genera Paludina, Cyrena, Unio, and Cypris. These beds are valuable, as 
producing the well-known Oxford ochre. The high-level gravel belongs 
to the period of the northern drift, and is so called because it occupies the 
highest ground in the district, as at Wj^tham Hill, where it attains an 
elevation of 583 feet above sea-level. It does not contain any organic re- 
mains, and is composed of well-rounded quartz pebbles. The low-level 
gravel is quite distinct in its origin, being formed almost entirely of local 
rocks, and containing water-worn Oolitic fossils, such as Terebratulae, and 
fragments of Belemnites. South of Abingdon, where the surface-rocks 
are cretaceous, it passes into a flint gravel, evidently derived from the de- 
nudation of the chalk of the district. The only remains belonging to the 
period when it was deposited are those of elephants, probably Elephas 
primigenius. From the position of this gravel, which extends into the 
valleys of the Windrush and Evenlode, and other tributaries of the 
Thames, we may conclude that it was formed at a comparatively recent 
period, when the ridges of Coral Eag were dry land, and what are now 
river-valleys were a series of shallow lochs, similar to those on the west 
coast of Scotland. 
At the meeting of January 13th, 1863, the President, the Eev. Professor 
Henry Griffiths, in his Address referred at length to some interesting 
geological phenomena, peculiar to ]S'orth and South Wales, with regard to 
the Old Eed Sandstone, and particular attention was drawn to that system 
of strata. The President then minutely described the series of fossil ich- 
thyolites of that age, lately added to the collection of the Koyal Institu- 
tion. 
