Mr. J. Prestwich on an Artesian Well at Kentish Town. 81 



thinks it probable that the superficial brick-earth of the district 

 under notice was formed in a land-locked lagoon, subject to periodical 

 freezing; and that the "elephant bed" at Brighton is one of its 

 many and variable equivalents (in this case probably subaerial). The 

 brick-earth area has been subsequently encroached upon by the 

 estuaries of Pagham, Portsmouth, &c. ; and the successive oscillations 

 in the level of the land are evidenced in the estuarine deposits and 

 submerged forests of Pagham, Bracklesham, Portsmouth, &c. With 

 regard to the latest movements, the author's observations showed 

 that from Lewes Levels to Chichester Harbour, and on to Hurst 

 Castle, the coast exhibits signs of undergoing elevation at the present 

 day. The coast of the Isle of Wight opposite seems on the contrary 

 to be suffering depression, whilst the back of the island exhibits some 

 curious signs of local oscillation. 



November 21, 1855. — W. J. Hamilton, Esq., President, in the 

 Chair. 



The following communications were read : — 



1. " Notice of the Artesian Well through the Chalk at Kentish 

 Town." By Joseph Prestwich, Jun., Esq., Sec. G.S. 



The boring of this well has pierced the following succession of 

 beds : — London Clay, 236 feet, — Woolwich and Reading series, 

 ei^feet, — Thanet Sands, 27 feet, — Middle Chalk (usually termed 

 " Upper Chalk " in England), 244^ feet,— Lower Chalk, 227^ feet,— 

 Chalk marl, 172 feet, — Upper Greensand, 59 feet, — Gault, 85 feet, — 

 and then 176^ feet of a series of red clays with intercalated sandstones 

 and grits. Altogether amounting to 1290 feet. It was expected 

 that, in accordance with the general relations of the lower members 

 of the Cretaceous series as they come to the surface in the districts 

 North and South of London, that the sands of the Lower Greensand 

 formation would be found immediately to succeed the Gault in the 

 boring. Instead of the sands in question the red sandy clays have 

 presented themselves, and the question of the probability of obtain- 

 ing a supply of water by deejier boring depends upon the fact 

 whether these red clays are a local variation of the Gault, and over- 

 lie the usual Lower Greensand, or whether the lower Cretaceous 

 deposits have here put on a new character altogether. The very 

 few fossils met with in the Clays speak strongly in favour of their 

 being true middle Cretaceous lying above the horizon of the Lower 

 Greensand; but the occasional occurrence in the clay of large rolled 

 fragments of syenite, j)ori)hyry, basalt, hornstone, and old sandstone, 

 and its general mineral features, seem to indicate a littoral character 

 for these deposits, and to point to the possible neighbourhood of a 

 ridge of older rocks, which have modified the conditions under which 

 the lower cretaceous beds were formed in this area. The considera- 

 tion of this important subject was referred to a Committee, who v.ill 

 report upon it at a future n>eeting of the Society. 



Phil. Mag. S. 4. Vol. 11. No. 69. .Jan. 185G. G 



