180 — . Dr Arber, On a little-known 
On a little-known concealed coalfield in Oxfordshire. By E. A. 
NEWELL ARBER, Sc.D., F.G.S., Trinity College. 
= 
[Read 22 November 1915.] 
At the present time the existence of only two wholly con- 
cealed coalfields has been proved in this country. Both of these 
lie in the very large hidden area to the South of the Midland ° 
fields, and to the Hast of the exposed or partly exposed fields of 
the West of England. This district, including the Home and- 
Southern Counties and East Anglia, may be conveniently sub-— 
divided, though in a purely arbitrary manner, into two nearly” 
equal halves by a line joining Bristol and London. In the more 
Southern section lies the Ként coalfield, which is still the only 
wholly concealed Coal Measure area of which we have any real 
knowledge. It was first proved in 1890. ; 
The fact however is often overlooked that the first entirely — 
concealed field discovered in England lies in part at least in 
Oxfordshire, in the Northern section of our district. Coal 
Measures were here proved in or before 1877, in a boring at ~ 
Burford Signet near Witney. It is true however that, with the 
possible exception of another boring at Lower Lemington near 
Batsford, the details of which have only recently been made known 
to us, no progress has since been made in the matter of probing 
the nature, extent and resources of the Oxfordshire field. 
While unfortunately no new facts are available for publication 
here in regard to this coalfield, it may be worth while to reconsider 
briefly the present evidence, in the light of the better knowledge 
which we now possess of the adjoining coalfields, 
The accounts which have been published of the Burford 
Signet Coal Measures are neither so explicit nor as detailed as 
one could wish. Situated a little to the South of Burford, and 
to the West of Witney in the S.W. corner of Oxfordshire, not far 
from the Gloucestershire border, the boring in question was put 
down between 1875 and 1877. The Mesozoic cover of Jurassic 
and Triassic rocks was only 1184 ft. in thickness. The o.D. of 
the boring was 350 ft. Translating the record with reference to 
this constant, we find that the Coal Measures were struck at 
834 ft. o.D. and that 226 ft. of the same rocks were penetrated*. 
* De Rance, C. H., Trans. Manchester Geol. Soc., Vol. xiv. p. 437, 1878; Rep. 
Brit. Ass. Dublin (1878), p. 382, 1879; see also Woodward, H. B., Jurassic Rocks 
of Britain, Vol. 1v., Mem. Geol. Surv., 1894, p. 803. 
