SCIENCE-GOSSIP. 



33 



. in England is the ten-yard seam of the Dudley 

 coalfield, but this is quite exceptional, a few feet 

 being generally the maximum. These coal seams 

 represent successive periods during which a 

 luxuriant and very characteristic vegetation covered 

 an old, low-lying swampy land surface, which was 

 subject to frequent oscillations of level and 

 consequent incursions of the sea, each of which 

 resulted in the deposition of sand and mud on the 

 peaty matter that had accumulated during the 

 previous period of vegetable growth. At last a 

 marked upheaval brought about conditions 

 unfavourable to further development of these in- 

 cipient coal beds, thus bringing the Carboniferous 

 period to a close. Subsequent disturbances 

 eventually modified in large measure the general 

 distribution of the coal-bearing strata. Together 

 with the underlying formations they were thrown 

 into a series of longitudinal and transverse folds. 

 Nature's ceaseless agents of destruction — air, frost 

 and water — came into play, and slowly but surely 

 removed the crests of these folds, wearing their 

 way down to still lower and lower strata, until the 

 coal measures, and in many cases the underlying 

 beds, disappeared. On the other hand, the coal 

 measures between the folds being from their 

 position less exposed to denudation, remained 

 comparatively intact, but isolated from those with 

 which they had formerly been continuous, lying in 

 troughs or basins surrounded by older rocks. 



Thus one of the folds above referred to extended 

 north and south from the Cheviots into the heart 

 of the Midlands, forming a ridge now known as 

 the Pennine Chain, with its strata dripping east 

 and west. L'ntold ages of wear and tear have, 

 however, stripped the summit of this ridge of its 

 coal measures, laid bare the millstone grit below, 

 and to a large extent the carboniferous limestone 

 In this way the coalfields on the east of the 

 Pennine Range became separated from those on 

 the west, while a similar disturbance and denuda- 

 tion that appears to have taken place subsequently 

 in a transverse direction through the northern 

 parts of I-ancashire and Yorkshire have cut off 

 the Northumberland and Durham coalfield from 

 that of Yorkshire, and also isolated thi land 



from the Lancashire coalfields In a similar 

 manner, the coal basin of the forest ol Dean has 



been separated from that of South Wales The 



intervening country is now ! upied by 



rock* far older than the carboniferoi 



all enpo^ol by denudation N ■ amples 



.] ba lins than the ■■• two 'I be 



coal measures occupy a dish lhaped hollow formed 



by the underlying mill .tone grit which crops up all 



•:ther wiih the i arbi aileron . li 



* forms at the SUrl ■ ■ ,i i|„ : 



,outh V.'alci coalficl •■] ,,,. i|,,. 



south by a tract of rocks consisting of carboniferous 

 limestone, which in many places has been denuded 

 down to the underlying formation known as the 

 Devonian or Old Red Sandstone. These occupy 

 the extreme southern portions of Pembrokeshire 

 and Glamorganshire, but their continuity is inter- 

 rupted by the bays of Swansea and Carmarthen, 

 and also, just south of Cardiff, by the estuary of 

 the Severn, but on the eastern side of the estuary 

 they reappear in the form of the Mendip Hills of 

 Somersetshire. Still further east they disappear 

 under newer formations, the whole tract being one 

 of the transverse folds formed after the close of the 

 Carboniferous period, and as we shall see later it 

 has an important bearing on the question of coal 

 in our southern counties. On the northern flanks 

 of the Mendip Hills we find the millstone grit and 

 coal measures of the Bristol coalfield, largely 

 hidden, however, by newer deposits of secondary 

 age, and only appearing at the surface where these 

 have been removed by denudation. 



We are now in a position to appreciate the 

 reasoning by which Mr. Godwin-Austen, in 1S55, 

 was led to put forward the theory that an exten- 

 sion of these western coalfields might be found at 

 a workable depth under our south-eastern counties. 

 At first sight the idea seemed a wild one. In 

 proceeding eastwards from Bristol we meet in 

 succession immense thicknesses of newer secondary 

 rocks, all dipping eastwards in such a manner as 

 apparently to place the palaeozoic rocks at a 

 depth of at least six or seven thousand feet below 

 the surface in the neighbourhood of London, and 

 consequently entirely beyond our reach. Besides, 

 there seemed no guarantee that deposits of 

 carboniferous age existed at all so far east ; the 

 formation might thin out, or, if not, might change 

 its character in so great a distance — a not unlikely 

 possibility. Mr. Godwin-Austen was able to reveal, 

 however, certain points of similarity between the 

 coalfields of Belgium and norlh-east France and 

 those of Somersetshire and South Wales, and 

 also between the Ardennes district and the Mendip 

 Hills, which respectively bounds those coalfields 

 on tin! south. The Ardennes form an elevated 

 region of pal.r-ozoic rocks, bearing on their 

 no 1 1" 111 slope a scries of long narrow detached 

 1 oal troughs, streti hing south-west along the valley 

 of the Meusc from Aix la-Chapelle through Liege 

 uid Namur, and continued through Mods and 

 roi to tin French frontier, and then uorth- 

 11 1 by Valenciennes and Douai to within ten 

 mid of Si I > 1 1 1< 1 or thirty from < Calais, 1 • om 

 the ph) ical tructure of the district, the litho 

 • harai tci of the strata, and the organii 

 remains which they contain, Mr. Godwin Austen 

 was convinced thai the anticlinal 01 ridgesol the 



rVrdenni 1 a 1 ontinua 1 thai ol the Mendip i, 



and thai if we could sti Ip south easl England ol its 



