Upon which it stands. A mile further on, in the same direction,
stands a third of these columnar remains, called the Ass’s Ears ; and
still further on for about another mile, rising as an islet from the
sea, detached from the main land, is seen Speery Bock, the last
visible portion of this great dike.
There is no difficulty in tracing the relationship of these rocks
as portions of the same great dike, because in character and composition
they agree exactly, while the rocks which enclose them are-
of a very different construction, consisting for the most part of
unstratified blue basaltic, hard-red, and other marls, containing
embedded crystals of augite, and traversed in all directions by
numerous very small dikes. These features are so intimately
associated with the great crater of Sandy Bay that it is difficult to
omit noticing them in connexion therewith ; but, in tracing out the
geological structure of the Island in due order, their introduction at
this point is somewhat out of place, as will be understood when it is
remembered that they were certainly formed after, perhaps long
after, the great volcano had ceased to be active; and as yet we have
not seen what became of the products cast outside of the crater-
walls during its activity.
With the intention, then, of returning to this subject in connexion
with the denudation and probable age of the Island, let us take
a view of what surrounds the great crater edge, or Sandy Bay Bidge,
on its northern, eastern, and western sides—in other words, the
great masses of lavas, ashes, and mud, which, ejected from the crater,
have built up the remaining portions of the Island.
We find no trace whatever of granite or any other primitive or
plutonic rocks, or indeed any formation to encourage the slightest
suspicion of a continental land having ever occupied that particular
latitude and longitude where St. Helena now stands. Continental
land may at some extremely remote period have occupied the same
place, but, be this as it may, there can be little doubt that, previous
to the appearance of St. Helena, the broad expansive South Atlantic
-swept over the site it occupies; and the first sign of disturbance
there was probably a bubbling and spouting up of the water on a
vast scale, just at or near to the spot now called Sandy Bay Beach.
Then followed a stream of molten lava, shot up from the depths of
the ocean, and, guided by the south-east wind, falling into it again
more on one side than the other, laid the foundations of that pile,
e 2