20O CARBONIFEROUS. 



Mines of Lead, Iron, and Manganese have been opened in dififerent places in the 

 Cuhii-measures. 



The beds of Culm stretch across the country from Barnstaple Bay and Bideford 

 towards Chiltlehampton west of South Molton, and they have been worked at 

 different periods, although never with any great profit. They vary from 6 inches 

 to 14 feet in thickness, occurring in lenticular masses, and at different horizons. 

 They may be seen at Greenacliff on the coast near Bideford, Hiscott, and Umber- 

 leigh. The softer varieties of culm, when ground to a powder, are sold as a 

 pigment, under the name of 'Bideford Black.' As a fuel it is useful for lime- 

 kilns, etc. Murchison has suggested that possibly some of the culm-strata of 

 Devon, devoid as they are of any workable coal, may yield bituminous products 

 by the application of heat. 



The beds of grit are sometimes sufficiently developed to be useful for building- 

 purposes and road-metal, as near Chudleigh, while flagstone-beds are worked near 

 Launceston and at Ashwater, Beaworthy, and other places west of Oakhampton. 

 The Grinshill freestone has been worked near Bideford. Beds suitable for roofing- 

 slate have been obtained at Boscastle. 



According to Sedgwick and Murchison, some of the shales are calcareous, and 

 contain masses of a variety of Rottenstone like that in Derbyshire. (See p. 167.) 



The Culm-limestones are lenticular and impersistent, often passing into calcareous 

 shale. In the large quarries seldom more than a third or fourth part can be burnt 

 for lime ; the alternating bands of dark indurated shale are used for flagstones or 

 coping-stones. 



The soil is usually poor, and the area is largely made up of rough pasture, wood- 

 land and moorland ; but, as Mr. Ussher has remarked, the rocks afford some very 

 charming river-scenery, and locally exhibit very pleasing contours.^ 



POSSIBILITY OF COAL-MEASURES IN THE EAST AND SOUTH-EAST OF 



ENGLAND. 



It has been a fertile topic for speculation whether other Coal- 

 basins may be met with beneath the Secondary and newer rocks, 

 of the east and south-east of England. Although, as before 

 mentioned (see p. 149), the idea had occurred to De la Beche, the 

 subject was first discussed in a very elaborate memoir by Mr. R. 

 A. C. Godwin-Austen. 



Judging from facts brought to light in working the Coal- 

 measures of Belgium and the North of France, " and reasoning 

 also on theoretical considerations connected with the extension 

 of the old coal-growth in the west of Europe, Mr. Godwin-Austen 

 concluded that Coal-measures might possibly extend beneath the 

 south-eastern part of England." Illustrating his remarks by a 

 map, " he showed that the Coal-measures which thin out under the 

 Chalk near Therouanne probably set in again at or near Calais, and 

 are prolonged (beneath the Tertiary strata and the Chalk) in the 

 line of the Thames Valley parallel with the North Downs, and 

 continue thence under the valley of the Kennet, into the Bath and 

 Bristol coal area. He showed, upon well-considered theoretical 

 grounds, that the Coal-measures of a large portion of England, 

 France, and Belgium were once continuous, and that the present 

 coal-fields were merely fragments of a great original deposit, which 

 he inferred had been broken up in two directions previously to the 



^ Physical Features of Devonshire, Trans. Devon Assoc. 1S80. 



