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 referrible 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 lleccnt 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. 



* Gctl. Trans., Si-fond Scries, vol. i. j:art ii. \i. C97. 

 f Mo. of Captain 1J. Hull. 



