134 NEWER, PLIOCENE PERIOD. [Ch. X. 
the globe will bring to light some of the most striking examples 
of marine strata upraised to great heights during comparatively 
modern periods. 
From the observations of Dr. Jack, it appears that in the 
island of Pulo Nias, off the west coast of Sumatra, masses of 
corals of recent species can be traced from the level of the sea 
far into the interior, where they form considerable hills. 
Large shells of the Chama gigas (Tridacna, Lamk.) are scat- 
tered over the face of the country, just as they occur on the 
present reefs. These fossils are in such a state of preservation 
as to be collected by the inhabitants for the purpose of being 
cut into rings for the arms and wrists *. 
Madeira. — The island of Madeira is placed between the 
Azores and Canaries, in both of which groups there are active 
volcanos, and Madeira itself was violently shaken by earth- 
quakes during the last century. It consists in great part of 
volcanic tuffs and porous lava, intersected in some places, as 
at the Brazen Head, by vertical dikes of compact lava-f. Some 
of the marine fossil shells, procured by Mr. Bowdich from this 
island, are referable to recent species. 
These examples may suffice for the present, and lead us to 
anticipate with confidence, that in almost all countries where 
changes of level have taken place in our own times, the geo- 
logist will find monuments of a prolonged series of convulsions 
during the Recent and newer Pliocene periods. Exceptions 
may no doubt occur where a particular line of coast is sink- 
ing down, yet even here we may presume, from what we know 
of the irregular action of the subterranean forces, that some cases 
of partial elevation will have been caused by occasional oscilla- 
tions of level, so that modern subaqueous formations will, here 
and there, have been brought up to view. 
We shall conclude by enumerating a few exceptions to the 
rule above illustrated — instances of elevation where no great 
earthquakes have been recently experienced. 
* Geol. Trans., Second Series, vol. i. part ii. p. 397. 
f MS. of Captain B. Hall. 
