322 
ELEMENTS OF GEOLOGY. 
Middle 
Lower 
OOLITE— Continued. 
(d. Coral rag. 
(e. Oxford clay, and Kelloway rock. 
Cornbrasli and Forest marble. 
J g. Great Oolite and Stonesfield slate, 
j h. Fuller’s earth. 
i. Inferior Oolite. 
The Upper Oolitic system of the above table has usually 
the Kimmeridge clay for its base; the Middle Oolitic sys¬ 
tem, the Oxford clay. The Lower system reposes on the 
Lias, an argillo-calcareous formation, which some include in 
the Lower Oolite, but which will be treated of separately 
in the next chapter. Many of these subdivisions are distin¬ 
guished by peculiar organic remains; and, though varying 
in thickness, may be traced in certain directions for great 
distances, especially if we compare the part of England to 
which the above-mentioned type refers with the north-east 
of France and the Jura Mountains adjoining. In that coun¬ 
try, distant above 400 geographical miles, the analogy to 
the accepted English type, notwithstanding the thinness or 
occasional absence of the clays, is more perfect than in York¬ 
shire or Normandy. 
Physical Geography. —The alternation, on a grand scale, 
of distinct formations of clay and limestone has caused the 
oolitic and liassic series to give rise to some marked fea¬ 
tures in the physical outline of parts of England and France. 
Wide valleys can usually be traced throughout the long 
bands of country where the argillaceous strata crop out; 
and between these valleys the limestones are observed, form¬ 
ing ranges of hills or more elevated grounds. These ranges 
terminate abruptly on the side onwvhich the several clays 
rise up from beneath the calcareous strata. 
The annexed cut will give the reader an idea of the con¬ 
figuration of the surface now" alluded to, such as may be seen 
Fig. 298. 
Lower Middle Upper London 
Oolite. Oolite. Oolite. Chalk. Cla3^ 
Lias. Oxford Clay. Kim. Cla^'. Gault. 
in passing from London to Cheltenham, or in other parallel 
lines, from east to west, in the southern part of England. It 
has been necessary, how^ever, in this drawing, greatly to ex¬ 
aggerate the inclination of the beds, and the height of the 
several formations, as compared to their horizontal extent. 
