TRANSACTIONS OF SECTION C. 647 



twenty miles in width. As it approaches the upper eStuaty of the Severn it is 

 represented by the outlying coal-tield of the Forest of Dean, and the three par- 

 tially or wholly covered fields to the north of the Mendip Hills, distributed through 

 an area measuring forty-five miles from north to south. The wedge-like syncline, with 

 its more or less connected coal-fields, continues to widen eastwards, its northern 

 boundary being probably represented by a line drawn from the northern rim of 

 the South Welsh coal-fi"eld to the north of the Forest of Dean, and continued due 

 I'ast beneath the Secondary and Tertiary rocks to some point between Walton-on- 

 the-Naze and the mouth of the Blackwater. It passes through Gloucester, 

 Eissington, in the valley of the Windrush, Blenheim, Kirtlington, Quainton, 

 Luton, Bishop's Stortford, Dunmow, Braintree, and Colchester. The width of 

 this great tectonic syncline between Colchester and Dover is about fifty miles, 

 and it occupies nearly the whole of the London Tertiary basin, which, it must be 

 noted, is of the same wedge shape, wideniog to the east. 



The boring recently described by Mr. AVhitaker at Culford, near Bury 

 St. Edmunds, in which a slate rock, probably of Silurian or pre-Silurian age, was 

 struck at a depth of G37 feet G inches from the surface, shows that in all probability 

 that area is an anticlinal area. About forty -two miles to the south, in the deep boring 

 at Harwich, the Yoredale shales come in. Both these points are, be it remarked, 

 to the north of the line in question. Both indicate a Palreozoic area in Suffolk 

 and northern Essex older than the Coal-Measures, and similar to that on the same 

 meridian in South Wales and Gloucestershire which lies to the north of the 

 western coal-fields. We have, therefore, not merely a well-defined Pembroke- 

 Mendip anticline forming the southern boundary of the coal-fields both in the 

 west and in the east, as proved by the south-eastern coal-field at Dover, but also 

 evidence of the continuation of the South Welsh pre-Carbonilerous barrier of 

 Hull, which forms the northern boundary of the visible coal-fields due eastwards 

 into Suffolk. It may therefore be reasonably inferred that similar coal-fields, 

 isolated from each other by tracts of older rocks, are to be found in the South 

 Welsh syncline where it lies buried beneath the Secondary and Tertiary strata. 

 In other words, we may conclude that there are coal-fields in North Wilts, in the 

 counties of Berk.s, Oxford, and Buckingham, and the Tertiary basin of the Thames 

 within the limits laid down above, and in a direction indicated in 1871 by the 

 Coal Commissioners. 



One such coal-field, indeed, has already been discovered in a deep boring at 

 Burford, near AVhitney, in the valley of the Windrush. The discovery, however, 

 has unfortunately not been followed up, and we do not know whether it is of wide 

 <;ast and west range, similar to that of South Wales, or of Bethune and Namur, oi- 

 whether it is small and unimportant, like some of the smaller coal-basins north of 

 the Mendip Hills. It ofl'ers a sure basis for other deep borings, which may have 

 the same industrial effect on Oxfordshire as those which have extended the range 

 of the buried Coal-Measures in northern France, ninety miles to the west of 

 Charleroi, and converted a purely agricultural into a great manufacturing district. 

 There is no practical difficulty arising from the depth at which the Coal-Measures 

 may be expected to occur in this region. At Burford they were struck at 

 1,184 feet from the surface, and at Dover at 1,113 feet below high-water mark. 



The borings in the area of the London Tertiaries prove that the Palfeozoic rocks are 

 not buried to'a greater depth than about 1,200 feet below sea-level, and in Hertford- 

 shire to as little as 796 feet. The most important collieries in England are carried 

 on at depths ranging from 1,500 to more than 3,000 feet. 



The new light thrown upon the question of the buried coal-fields by recent dis- 

 coveries places it in a very difi'erent position from that which it occupied in 1871, 

 when Godwin-Austen, Prestwich, and Hull gave their evidence before the Ivoyal 

 Commission. The boring at Dover, revealing the existence of a valuable coal-field, 

 now offers a fixed point for further discovery in south-eastern England. That at 

 Burford ofi'ers a similar basis for the proving of the Oxfordshire coal-tield. The many 

 other wells and borings made in the area of London, and as far north as Bury St. 

 Edmunds, also afibrd important information as to the northern boundary of the 

 productive South W^elsh syncline. The development of our mineral wealth is of 



