756 PROF. J. W. JUDD ON THE NATURE AND RELATIONS OF 
(6) As to whether the Upper Oolites—which exhibit such a 
thickness in the Wealden boring, and are again found as deep-water 
beds on the northern side of the axis—were also continuous over 
the latter, we have at present no certain evidence. Among the 
derived fossils in the Lower Greensand of the North Downs I have 
not been able to identify any as belonging to undoubtedly Upper- 
Oolite species. The beds at Shotover probably indicate that, during 
the Upper-Oolite period, the elevation which continued through a 
great part of the Neocomian period had already begun. 
(7) As no beds of Middle-Oolite age have as yet been detected in 
situ beneath London, we are led to conclude that the whole of them 
were removed during the great upheaval and denudation of the 
Paleeozoic ridge which undoubtedly took place during the latter 
part of the Neocomian period. This will account for the abun- 
dance of fragments derived from the Middle and Lower Oolites 
which are imbedded in the Lower-Greensand strata deposited along 
the southern flanks of the ridge. Of the importance of this move- 
ment of elevation, with its accompanying denudation, we have the 
clearest proofs. It was probably as this mcvement of elevation was 
gradually being replaced by one of subsidence, and while portions of 
the remnant of the Great-Oolite strata were still above the waters 
of the ocean, that the curious and anomalous strata lying between 
the Gault and the Great Oolite at Richmond were formed. These 
consist in part of the reconstructed materials of the Great Oolite, 
and in part of pebbles brought from the shores of the period, con- 
sisting of some exposed portions of the Paleozoic ridge. 
(8) During the subsequent Gault and Chalk periods a continued 
submergence of the great Palzozoic axis went on, the movement of 
subsidence more than keeping pace with the work of sedimentation. 
But that this downward movement was not without interruptions, 
we have now abundant evidence within the metropolitan area itself. 
The rock of the Zone of Belemmites plenus and the Chalk Rock afford 
evidence that, at the close of the Cenomanian and Turonian periods 
respectively, pauses in the deposition of sediment took place, ac- 
companied by some removal and redeposition of beds already formed. 
What the extent of this interruption to subsidence or partial re- 
elevation during these periods was, it may be difficult to determine ; 
but it seems certain that thick and important deposits were, in 
certain portions of the continental area, deposited during these 
breaks in the succession of our Chalk strata, and that these move- 
ments, in which the great Paleozoic axis participated, were wide- 
spread in extent and important in their consequences. 
B. The Water-supply of the Metropolis. 
The general analogy between the strata of the Paris and London 
basins iong ago suggested to geologists the possibility of obtaining 
for the latter city those deep-seated supplies of water which feed 
the great Artesian wells of the former. But, as Mr. Godwin- 
Austen showed by a priori reasoning, and several deep wells in the 
