64 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 24, 
ceded them ; and at the same time there must have been a persist- 
ence of reef conditions within the limit of the migration of corals 
during the Kimmeridge and Portland period, and without the area 
of Western Europe. 
If the Neocomian is regarded in a general sense as the marine 
equivalent of the Wealden, some insight may be obtained concerning 
the great elevation of parts of the Jurassic sea-bed which occurred 
before the commencement of the Cretaceous era. The opinion of 
Elie de Beaumont, that a great upheaval, which he has named the 
system of the Cote d’Or, took place before the sediments of the lower 
Cretaceous seas began to form, is worthy of careful consideration. 
It would appear that long ranges of the Jura and Cevennes, and 
granitic rocks covered with Oolitic outlers were tilted and elevated 
before the sediments of the Neocomian period were deposited uncom- 
formably and horizontally in relation to them. If this was so, the 
varying bathymetrical conditions already noticed as characterizing 
the sea-bottoms of the Upper Oolites culminated in an upheaval, 
which produced land in one portion of the area of Western Europe, 
and determined the presence of the physical conditions favourable 
for coral-life in another. 
The Gault. 
When the species forming the Coral-fauna of the Gault are com- 
pared with recent forms, there is no difficulty in asserting that they 
were dwellers in deep water, and not within the range of reefs. 
Some of them, probably, were littoral kinds. Ali are specifically 
distinct from the Neocomian corals, and present a different facies. 
Nothing is known concerning the reefs of this period; and the few 
species of the generally very uncoralliferous strata of the Continent 
are deep-sea forms. 
Upper Green Sand.— Upper and Lower White Chalk Strata. 
The gradual subsidence of great spaces of the sea-bottom, which 
probably determined the peculiar fauna of the Gault, and the absence 
of reefs, appears to have continued in some localities during the de- 
position of the Upper Green Sand strata; whilst it was preceded in 
others by an elevation of the old sediments. The coral fauna of the 
English Upper Green Sand is representative of that of the Gault, but 
the species differ. There were littoral and deep-sea forms in both ; 
and in the south-west of England, at Haldon, there was a reef. On 
the Continent, the strata of the period indicate every known variety 
of deposit, and very varying bathymetrical conditions. Reefs suc- 
ceeded various deposits, and occupied different geological horizons ; 
and all had a definite relation to each other, both in the identity of 
the species and the accompanying mollusca. 
It is impossible to separate the English Upper Green Sand and 
Lower White Chalk from the formations at Gosau, in Austria, and 
the reefs in the south of France, where Hippurites are mixed up, 
like gigantic Chamas, with masses of compound corals to form reefs. 
Few generalizations have been more useful than those of Messrs. R. 
