438 
THE GEOLOGIST. 
tlirougli wliicli the major part of the Thames flows, are of marine species, 
and most of them extinct. In the superficial gravel have been found 
fluviatile shells, most of them of recent species, with the remains of ele- 
phant, rhinoceros, hippopotamus, and other large terrestrial quadrupeds." 
As regards earthquakes, as a geological dynamic. Hunter states — 
" I formerly observed that earthquakes very probably raised islands ; 
tliat on the surface of such there would be found shells, and in vast quan- 
tity, recent, dead, and fossilized. . . . This upraising of the bottom of the 
sea above the surface of the water, will also raise up along with it all the 
shell-fish that lay on the surface of the bottom, as also dead shells, and in 
the substance of the earth all the deeper-seated substances imbedded or 
enclosed in stone, chalk, cla}', etc., which I have said constitutes the true 
fossil. This appears to be the state of the case on and in the Island 
of Ascension ; the whole surface of this island is covered with shells, and 
some so perfect as to have their ligaments still adhering. There is, besides, 
a vast quantity of lava, and other volcanic matter, all of which shows it 
most probably arose in this way ; because such recent alteration in the sea, 
so as to have exposed so much of its bottom, and so recently as to have the 
animal part of the shell still adliering, and the very name implies its rise. 
I suspect that many of those shells found on land near the surface, on the 
tops of mountains, have been exposed in this way." — P. xlvii. 
Owen remarks on the ridiculous derivation of the name of the island : — 
" This is very ingenious ; but the superstitious Spaniard had little 
thought of the geological causes of the island, when he discovered it on 
the evening of ' Ascension Day.' " 
Poor Joao de Nova Galego little expected that he should be thus mis- 
quoted in the eighteenth century. 
With respect to the conditions under which mammalian remains are 
imbedded in comparatively recent geological deposits. Hunter wrote — 
" In peat, one could conceive that the trees had only to fall, and after- 
wards to sink down into it ; but I believe no such wood grows in peat, 
therefore they must have been brought there, and that only by water ; or 
[they may have] grown there prior to the formation of peat. But the 
animals which could come there had only to die on the surface, and in time 
they would also sink deeper and deeper into it ; and tliis I imagine might 
be the case with the beavers in this country, whose bones are found in the 
peat-mosses in Berkshire. Or, as peat is supposed to grow, we can con- 
ceive it rising higher and higher above such substance. 
" Bones are also found in gravel, clay, marl, loam, etc. ; and as we have 
found the ^ea-horse bones '^Hippopotamus^ in gravel, etc. in this countiy, 
I am inclined to think that such situations have been shores or arms of the 
sea, at last constituting mouths of rivers, where the animals have been 
accidentally swept awa}^ by floods, accidentally drowned, etc., where gravel, 
clay, etc", have subsided, as before described ; for it gives more the idea of 
being a consequence of the sea leaving the land than an effect produced by 
a continuance of the sea in the part, according to our idea of the form.ation 
of the true fossil. But the difficulty is to apply this to the bones of some 
animals that do not now exist in the same countries where they are found ; 
as also [to] the bones of animals that probably do not now exist in any 
country. 
" This looks like a destruction of the whole species of such animals at 
the time [during] which [those] animals were probably confined to such 
countries ; and which might also be the case with the beaver in this 
country ; and it being a more universal animal, its species is preserved in 
other parts. The same observations apply to the sea-horse {Jlippopola- 
mus\ as also to the elephant." .... 
