TEANSACTIONS OF SECTION C. 657 



a continuous sheet of these rocks from the central part of London for some miles 

 southward. How far south we cannot say. We can, however, limit the northerly- 

 extension, as in the northern part of London and beyond no Jurassic beds have 

 been found, On the east, too, along the valley of the Thames, they soon end oH", 

 though they may extend far beneath the broad tract of the Weald, and perhapu 

 also under some of the bordering chalk tract. 



The object of the various borings alluded to has been to get water from the 

 Lower Greensand, which formation comes next beneath the Gault at the outcrop 

 on the south, right through Surrey and Kent. The borings have, however, proved 

 that it thins out underground northward, not reaching so far as London. 



The only chance, therefore, of getting water from this formation near London 

 seems to be by tapping some older formation which may come into contact with 

 the Lower Greensand in some part of its underground course, and may be perme- 

 able enough to receive and to carry oft' some of its water. The Jurassic limestone 

 as yet found at Streatham is too compact for this, but the boring will be continued 

 for awhile in the hope of reaching beds of looser texture. 



Should the Company, however, feel compelled to abandon the work, it is to be 

 hoped that some means may be taken to carry it on as a scientific experiment, in 

 order to find out what formation comes beneath the Jurassic beds, which, in the 

 two borings that have pierced them, are succeeded by red sandstones and marls of 

 doubtful age, or by undoubted Devonian rocks. We have now another chance of 

 solving an important problem, the question whether Coal Measures occur along the 

 valley of the Thames. 



Note. — Since this paper was read the boring has been carried through the 

 Jurassic beds, which are only SS^ feet thick, and has entered a set of compact cal- 

 careous sandstones, grey and greenish grey, mottled with maroon-colour, probably 

 with beds of clay (specimens of which are not brought up by the boring-tool). 

 These beds are like those of Richmond and of doubtful age — New Red or Old 

 Red P 



4. On the Loiuer Carhoniferoiis Hods of Gloucester si lire. 

 By E. Wethered, 'F.G.8., F.C.S., F.B.M.8. 



In Gloucestershire there are two coalfields, namely, that of the Bristol and 

 Forest of Dean. The Carboniferous Limestone Series of Gloucestershire were long 

 ago divided by Sir H. De La Beche as follows : 



2,338 791 



The author has proposed some detailed alterations with regard to the Bristol 

 coalfield which are stated in the ' Quarterly Journal of the Geological Society' for 

 1888, p. 187, but the above divisions have been generally accepted under the 

 terms Lower Limestone Shales, Carboniferous Limestone, and Upper Limestone 

 Shales. Professor Hull has given a classification of the Carboniferous Series 

 throughout the country (' Quart. Journ. Geol. Soc' 1877), based on the various 

 stages which occurred during the deposition of the rocks. The author supports 

 the principle of that classification, and is of opinion that the Lower Carbonii'erou,s 

 rocks of Gloucestershire might be correlated with the same formation in the north 

 of England. If this could be done it might be possible to adopt terms for the respec- 

 tive stages which would apply to the north and south of England, and thus avoid 

 the complication of terms now in use. 



The author then recited the stages which occur in the Carboniferous Lime- 

 stone of Gloucestershire. Above the Old Red Conglomerate there appears a series of 



1888. u u 



