58 KEPOKT — 1866. 



Reflection vipon tlio order and nature of the rocks which surroimd the south- 

 eastern counties of England, whether on the coast of Franco, the Channel Islands, 

 or the western, midland, or northern counties of England, having- led me to adopt 

 an opposite conclusion, I beg to offer the following observations in explanation of 

 the view which I take, viz. that no ]3roductive coal-measures can reasonably be 

 looked for in Essex, Kent, Sussex, Middlesex, Herts, Hants, Bucks, Oxfordshire, 

 Suffolk, Norfolk, and the eastern counties, from Yorkshire southwards. In this 

 list Nottinghamshire is happily not included. To it must necessarily be added 

 all the numerous tracts wherein rocks older thaii the carboniferous rise to th" 

 surface, as in the greater part of Wales and Herefordshire, in all of which coal 

 cannot of necessity be found. 



Let us first test the value of the data afforded by observations in France, which 

 have led to the application of the above theory to the south of England. 



But although I diiFer from Mr. Godwin-Austen, the difference between us is not 

 great, inasmuch that I do not believe that my distinguished friend maintains that 

 a really valuable coal-field is likely to be found in the south-eastern counties, but 

 simply, that some carboniferous and older rocks may there underlie the younger 

 deposits. His memoir is, indeed, full of originality in tracing out the gradual position 

 of an old terrestrial area over v.'hieh the vegetation that formed the coal-fields pro- 

 bably extended. 



It is true that beds of coal of considerable dimensions are worked at Valen- 

 ciennes at once beneath the chalk, all the intervening formations which exist in 

 many other parts of the world being there omitted. This fact simply indicates 

 that at Valenciennes the coal-bearing deposits had formerly been elevated, so as to 

 constitute ancient lauds, and had not been afterwards depressed under the sea 

 during all the periods in which the Triassic, Liassic, and Jurassic formations were 

 accumulated in other tracts. These carboniferous strata of Valenciennes con- 

 stitute a portion of the southern edge or lip of the great coal-basin of Belgium, in 

 which country', together with the sulDJaceut Carboniferous and Devonian limestones, 

 they form those great undulations so admirably laid down in the geological map of 

 M. Dumont. The portion of these coal-strata which exists in France, and which at 

 Valenciennes dips at a high angle to the north to pass into Belgium, has been also 

 found to have a lateral extension on the strike for a certain distance to the west 

 beneath the Cretaceous rocks, i. e., towards the British Chaimel. 



By trials made through the Cretaceous rocks and other overlying deposits, 

 these same coal-strata have been proved to extend to the west of Bethune. But 

 they there gradually thin out to a narrow band, which diminishes to a wedge-lik(3 

 mass directed to W.N.W. The western limit of the better portion of the field has 

 been definitely proved by the fact that, in all the borings which have been made to 

 the east of a village called Flechenelle, Devonian limestones, schists, and grits filono 

 have been reached, the coal being thus completely omitted. 



For general purposes the geological map of France, by Messrs. Elie de Beaumont 

 and Dufrenoy, sufficiently explains this thinning out to the west of the Valenciennes 

 coal-field. My conclusions, however, are more specially drawn from a good statis- 

 tical coal-mining survey map of France, recently prepared by able civil engineers, 

 as laid down on the maps of the Depot de la Guerre, as well as from my own ob- 

 servations in the Boulonnais. On this map, every concession or grant of a right 

 to sink for coal (in number exceeding 200) is marked ; the results of each sinking, 

 and the depths being regularh' given. The limits of the coal-bearing strata on the 

 north and on the south of the Carboniferous Zone have been thus ascertained by 

 trials, all of which show that the Devonian rocks fiank on each side this narrow 

 tongue of coal-measures, the extreme point of which is at Flechenelle. Between 

 that village and Boulogne, Devonian rocks only are found under the secondarj^ 

 deposits in all the borings that have been made. It is only to the north of Bou- 

 logne, at Hardingen, that a detached mass of carboniferous limestone, with an 

 insignificant patch of worthless coal associated with it, is seen to be basined upon 

 those Devonian rocks which there rise to the surface. In short, all the practical 

 French geologists with whom I have conversed are of opinion that the coal-basin 



