908 J. PRESXWICH ON THE RANGE OE THE LOWER 



under London a succession of strata of the same character as those 

 met with in connexion with the Coal-measures of the north of France 

 and Belgium ; and we are confirmed in the hope I have before ex- 

 pressed that, to the north of the line just named, productive coal- 

 basins of similar character may be met with underlying the Chalk 

 and Tertiary strata of this country. 



The attempt to determine the strike of Devonian strata at Messrs. 

 Meux & Co.'s was not successful ; but the general direction of the 

 strata has been proved by the last deep boring at Crossness, near 

 Blackwall, undertaken by the Metropolitan Board of Works. In this 

 instance the Chalk and Gault were successfully traversed, when, in 

 place of the Lower Greensand, mottled red, grey, and greenish hard 

 sandstones and red, slightly calcareous, clays were met with ; but, 

 owing to the small size of the bore-hole, the specimens were so frag- 

 mentary and, as in the case at Kentish Town, so much mixed with 

 debris and fossils from the Gault and Chalk, that their determination 

 was for a time difficult. After, however, inspecting various speci- 

 mens obtained in passing through the 60 feet of these strata, and 

 eliminating all the sources of error, I have now no doubt of the 

 identity of the beds with those at Kentish Town. This would indi- 

 cate a strike somewhere between N.W. and S.E., or W.N.W. and 

 E.S.E., corresponding with that of the Palaeozoic rocks in the north 

 of Prance. A section of Crossness well, for which I am indebted 

 to the courtesy of the Board, is annexed (p. 913). 



In considering this question, it mast be borne in mind that what- 

 ever the relative position of the Devonian and Coal-strata may be, 

 there is one circumstance relating to their occurrence in this part of 

 England that is here likely practically to limit the winning of coal. 

 If, as we believe, the Lower Greensand extends underground from 

 its outcrop in Kent and Surrey as far as London, its presence in that 

 area would present a most formidable barrier to the sinking of 

 shafts to the Palaeozoic strata, owing to the difficulty of passing 

 through any great thickness of loose sands so highly charged with 

 water and under such a pressure. To the north of London, where 

 the Chalk and Gault rest directly on the Palaeozoic rocks, this impedi- 

 ment does not exist ; but how far the same order of superposition 

 may be maintained can only be determined by trials in various 

 places. The zone marked by the absence of the Lower Greensand 

 cannot be many miles in width, as this formation reappears, although 

 in less force than in Kent, from beneath the Gault in Bucking- 

 hamshire and Bedfordshire, 30 to 40 miles north of London, and 

 may be prolonged under part of the Chalk hills of those counties and 

 possibly of Hertfordshire. 



This brings me to the second point of importance determined by 

 Messrs. Meux & Co.'s well. Although the well at Kentish Town 

 had unexpectedly disclosed the existence of Palaeozoic strata directly 

 under the Gault, I have always felt convinced that the Lower 

 Greensand, so thick at Sevenoaks and Kedhill, extended to or near 

 to London, and that although the Tottenham-Court Road appeared 

 to me too near Kentish Town for a successful trial, I considered 



