The oak and laurel
have supplied many leaves. Of the triple-nerved laurels several are referred to
Cinnamomum. There are leaves also of a palm of which the genus is not
determined. Leaves also of proteaceous forms, like some of the Continental
fossils before mentioned, occur, and ferns like the well-known Lastraea stiriaca
(Figure 154), displaying at Bovey, as in Switzerland, its fructification.
The croziers of some of the young ferns are very perfect, and were at first
mistaken by collectors for shells of the genus Planorbis. On the whole, the
vegetation of Bovey implies the existence of a sub-tropical climate in
Devonshire, in the Lower Miocene period.
SCOTLAND: ISLE OF MULL.
In the sea-cliffs forming the headland of Ardtun, on the west coast of Mull, in
the Hebrides, several bands of tertiary strata containing leaves of
dicotyledonous plants were discovered in 1851 by the Duke of Argyll. (Quarterly
Geological Journal 1851 page 19.) From his description it appears that there are
three leaf-beds, varying in thickness from 1 1/2 to 5 1/2 feet, which are
interstratified with volcanic tuff and trap, the whole mass being about 130 feet
in thickness.
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