158 



SCIENCE-GOSSIP. 



The spot is almost within sight of Calais, where 

 the Coal Measures have been found at a depth 

 of 1,104 f ee t- The discovery of coal at Dover 

 is the first of a series of coal-fields which, look- 

 ing into the future, we may live to see stretch- 

 ing right away from Bristol, in the direction of a 

 line connecting that coal-field with the Pas de 

 Calais. Borings near the River Thames, in 

 reaching strata older than the Carboniferous, have 

 disposed of the possibility of Coal Measures being 

 found actually beneath London. But geologists 

 agree that the disappearance of Wealden Beds 

 between the North Downs and such places 

 as Richmond, Tottenham Court Road, Streat- 

 ham, Crossness, and Chatham, where borings 

 have been made, points to their having been 

 deposited against an axial east and west ridge, 

 which may contain the coal-basins for which we 

 are in search, and that, therefore, the range of 

 the Downs offers the greatest possibility of success. 

 Prestwich thought they should be looked for on 

 a line passing from Radstock, in Somerset, thence 

 through the Vale of Pewsey, and thus along the 

 North Downs to Folkestone. The ancient land- 

 surface rises so rapidly beneath London as to reach 

 a depth of but 795 feet from the surface at Ware, 

 in Herts, at which the Silurians were touched. 



Before the Dover boring was commenced, a 

 shaft was sunk to sea-level, i.e. 44 feet deep. It 

 must, therefore, be understood that in referring 

 here to depths of various strata, 44 feet must be 

 added to the measurements given in the sections 

 quoted in this article, unless stated otherwise. 



From the diagram it will be sesn that the Grey 

 Chalk extended to a depth of 91 feet, after which 

 followed a thickness of 39 feet of Chalk Marl 

 and 8 feet of Chloritic Marl, this represent- 

 ing the so-called Upper Greensand. The Gault 

 was of great thickness, reaching no less than 

 121 feet. Next followed the Neocomian, or Lower 

 Greensand. According to Professor Boyd-Dawkins, 

 660 feet of Jurassic strata were then bored through, 

 Portland Beds, Kimmeridge Clay, Corallian Series, 

 Oxford Clay, Kelloway Rock, and Bath, or Lower, 

 Oolite, all being represented. According to 

 Messrs. Brady, Simpson and Griffiths, the thick- 

 nesses were as follows : 



Grey Chalk and Chalk Marl .. 174 feet 



Chloritic Marl S ,, 



Gault .. .. .. .. .. 121 ,, 



Lower Greensand, Wealden and 



Hastings Beds .. .. .. 241 ,, 



Upper, Middle and Lower Oolites, 



and Lias . . . . .. . . 613 ,, 



To Coal Measures . . 1,157 f ee ' 



The Coal Measures were at length struck at 

 1,113 f eet from trie bottom of the shaft, whilst 



from 24 feet further down came reports of zj feet 

 of good house coal, containing, however, a thin 

 sandstone parting. The strata then gave con- 

 tinued evidence of their origin, the sandstones 

 being streaked here and there with coal, with, now 

 and then, valuable seams of the same material. 

 Omitting those of less than one-foot in thickness, 

 ten seams were encountered, yielding altogether 

 21 feet n inches of coal. 



In the valuable and concise paper read before 

 the North of England Institute of Mining and 

 Mechanical Engineers, by Messrs. F. Brady, 

 M.I.C.E., G. P. Simpson, F.R.G.S., and Nath. R. 

 Griffiths, an analysis of coal from the lower seams 

 in the Dover boring, gave the following result : 



Carbon . . . . . . . . 83-8 



Hydrogen . . . . . . 465 



Nitrogen . . . . . . . . -97 



Oxygen . . . . . . . . 3-23 



Owing to the high percentage of volatile 

 matters, Mr. Watteyne rejects the idea that the 

 Dover coals belong to the base of the formation, 

 in spite of some correspondence in structure 

 between some of the sandstones in the boring, and 

 those of the lowest regions of the Coal Measures 

 in Belgium. 



The great four-foot seam of good bituminous coal 

 was discovered at a depth of 2,177^ feet from the 

 top of the bore-hole, or 2,22iJ feet from the 

 surface. 



The important question remaining is to ascertain 

 whether by a continuation of the boring there is 

 the possibility of further coal seams being reached. 

 The fact of the seams being horizontal shows that 

 here, at any rate, if this be one of the detached 

 coal-basins, we are in the centre of such basin, but 

 this horizontality throws little light on the thickness 

 of the measures. The boring was continued 105 

 feet below the four-foot seam, a total of 1,173 feet 

 of Coal Measures being bored through. This is 

 more than one-half of the whole depth of the 

 boring, but from a mere stratigraphical point of 

 view it does not follow that there is no further 

 great thickness below. In South Wales we have 

 no less than 11,000 feet of coal-bearing strata, so 

 that there is no great impossibility of finding a still 

 greater thickness below. 



It is fairly possible to judge, however, as to the. 

 position which these Coal Measures bear strati- 

 graphically, from the fossils which have been 

 brought up by the boring-tool. The best specimens 

 of organic life were submitted to M. R. Zeiller, of 

 the School of Mines, Paris, for identification. 

 Vegetable remains from three levels were examined 

 with the following results. 



From a depth of 1,894 f eet from the surface the 

 following ferns were found: Odontopteiis (? Mari- 

 opteris spkenopteroides, Lesq.), Neuropteris sclieuzeri, 



