106 
GEOLOGICAL CHANGES. 
thesis of the transportation of the remains ; 
from equatorial regions. We can allege, with 
all the verity that belongs to the best pro¬ 
ved history, that the upper beds of the 
Oolite in the South of England, sustained a 
lofty vegetation, and that the land crowned 
with its leafy honours descended into the 
bosom of a deep and tranquil lake, whose 
bed it formed for many succeeding ages, in 
the course of which calcareous sands and 
clay were thrown down, mixed with the re¬ 
mains of lake and estuary amimals. This 
condition of things must have lasted some 
time as is evidenced by the vegetation of the 
Wealden, and must have been succeeded by 
another great change in the sea level, by 
w hich the ocean again resumed the place it 
had occupied in the Oolitic age, but with 
more uniformity and probably a gi eater 
depth. From this sea resulted the thick 
mantle of green sand and chalk which now 
overlaps the former deposits in the South 
West of England. 
The more solid beds of the Oolite hardly 
exhibit any trace of vegetation. 
A sort of shale composing the famous 
