558 Geological Society. 



facts : — it is capable of rising 130 feet above the surface of the 

 ground, and it has a temperature considerably higher than that of 

 the surrounding air. 



This well, the bottom of which, reckoning from the Ordnance 

 datum-line, is now 150 feet lower than that of any other well within 

 the London Basin, has revealed a number of facts which are of the 

 greatest interest to geologists. 



The Tertiary strata passed through present their usual characters. 

 The London Clay has a thickness of 160 feet, the Woolwich and 

 Beading Series of 60 feet, and the Thanet Sand of 23 feet. The 

 usual band of gren-coated flints separates the Tertiaries from the 

 Chalk. 



The Chalk was proved to be 671 feet thick under Richmond. Two 

 important horizons, the Chalk Rock and the zone of Belemnites plenus , 

 were recognized in it, and it was thus proved that the Upper Chalk, 

 or Senonian, is 300 feet thick, the Middle Chalk, or Turonian, 

 150 feet, and the Lower Chalk, or Cenomanian (including the Upper 

 Greens and, which is normal in character and about 16 feet thick), 

 less than 250 feet. 



The Gault presents its usual characters, subdivisions, and fossils ; 

 it is 201^ feet in thickness. At its base is the usual band of phos- 

 phatic nodules. 



Beneath the Gault was found 10 feet of impure sandy limestone, 

 with but few and imperfect fossils, and a second junction-bed at its 

 base. These beds are probably referable to the Neocomian. 



At this point the boring entered thick beds of oolitic limestone 

 with some subordinate bands of clay. The careful examination of 

 these has revealed the presence of many fossils — Brachiopoda, 

 Bryozoa, and Echinodermata being especially abundant, some of 

 them in a very perfect state of preservation. These fossils prove the 

 strata in which they occur, 87| feet in thickness, to be of the age 

 of the Great Oolite. 



A careful reexamination of the evidence in the case of the boring 

 made in 1878 at Meux's Brewery, proves that the 64 feet of oolitic 

 limestone, which was there found overlying the Devonian rocks, 

 is also of Great-Oolite age, though deposited under somewhat dif- 

 ferent conditions from those at Richmond. 



The Great-Oolite strata at Richmond rest on beds of red and 

 variegated sandstones and " marls," the former exhibiting much 

 false-bedding. These strata have not yielded any fossils ; but their 

 lithologieal characters seem to indicate that they belong to the 

 New Red Sandstone formation. These discoveries have an im- 

 portant bearing on several very interesting geological problems. 



(1) The great Palaeozoic ridge beneath the London Basin is shown 

 to have been overlapped, in part or altogether, by strata of the 

 Lower Oolites, the Lias being absent ! That representatives of the 

 Middle Oolites were also present is shown by the derived fossils in 

 the Xcocomian strata along the base of the Xorth Downs. 



(2) Pervious beds of the Lower Greensand, which probably 

 underlie part of the Southern Metropolitan area, are proved not to 



