Notices of Memoirs — W. Whital<er — Silurian in Kent. 469 



Martinique, with a discussion of the phenomena of the extrusion of 

 and subsequent destruction of the spine which have been described by 

 Lacroix and others, and a comparison of the eruptions of the two 

 islands. 



XI. — Ois" THE Finding of Siltteian Beds in Kent.^ By 

 W. Whitaker, B.A. (Lond.), r.R.S. 



A BOEING has lately been made, to a great depth, at Messrs. 

 Curtis & Harvey's works, on the Thames Marshes at ClifFe, 

 for the purpose of getting a supply of water, firstly from the Chalk 

 and then from the Lower Greensand. It has failed in this, the water 

 from both formations being too salt to be of any use ; but it has 

 succeeded in adding a geologic formation to the Kentish list, and that 

 the oldest yet found in the county. 



Details of the section will be given in a forthcoming Geological 

 Survey Memoir on the Water-supply of Kent. It should be noted 

 that the division between some of the formations is doubtful, but any 

 error from this cause is immaterial in the following abstract: — 



Feet. 

 Alluvium and River Gravel . . 77 \ 



656 (or more) 



208 (or less) )■ 1,074 feet. 

 96 (or less) 

 37 (or more) 



Upper, Middle, and Lower Chalk 



Gault 



Lower Greensand . 



Dark-grey clayey rock 

 Nearly the whole of the Chalk has been pierced, the topmost part 

 only being absent. The thickness given to the Gault is a little 

 more than in the borings at Chatham, Frindsbury, and Strood 

 eastward, and still more than at Erith (Crossness) westward. The 

 thickness given to the Lower Greensand is also more than at Chatham, 

 whilst at Erith there is none of this formation. 



The chief interest of the boring, however, lies in the facts that 

 the floor of the older rocks, which has been proved in many places 

 in Kent, was reached at a level of about 1,030 feet below Ordnance 

 Datum, and that the Palaeozoic formation found is of Silurian age, 

 nothing older than Devonian having been hitherto recorded from the 

 deep borings of the county, and that only at Brabourne, unless the 

 red rocks at Crossness should turn out to be of like age. 



The proof of the Silurian age of the lowest beds is given by the 

 occurrence of fossils at the depth of 1,063 feet, Atrypa reticularis and 

 Plectartibonites having been determined at the Palaeontological Depart- 

 ment of the Geological Survey by Mr. H. A. Allen, from samples of the 

 cores sent by Mr. Baldwin Latham. There are traces of other fossils. 

 The practical value of the boring is that it puts a northern limit 

 to the Kent coalfield in its neighbourhood. 



XII. — On a case of Thrttst and Ckush-brecciation in the Magnesian 

 Limestone, Co. Durham.^ By David "Woolacott, D.Sc, F.G.S. 



ALONG the two miles of cliff between South Shields and Marsden 

 the breccias that formed so marked a peculiarity of the Magnesian 

 Limestone of North-East England are best exposed. The rocks seen are 



1 Read before the British Association, Section C (Geology), DubUn, Sept. 1908. 



