rock. The strata of the latter are frequently arched with
perfect symmetry, and the appearance of some of the masses
is in consequence most singular. Pernety [8] has devoted
several pages to the description of a Hill of Ruins, the
successive strata of which he has justly compared to the
seats of an amphitheatre. The quartz rock must have been
quite pasty when it underwent such remarkable flexures
without being shattered into fragments. As the quartz
insensibly passes into the sandstone, it seems probable that
the former owes its origin to the sandstone having been
heated to such a degree that it became viscid, and upon cooling
crystallized. While in the soft state it must have been
pushed up through the overlying beds.

In many parts of the island the bottoms of the valleys are
covered in an extraordinary manner by myriads of great
loose angular fragments of the quartz rock, forming "streams
of stones." These have been mentioned with surprise be
every voyager since the time of Pernety. The blocks are
not water-worn, their angles being only a little blunted; they
vary in size from one or two feet in diameter to ten, or even
more than twenty times as much. They are not thrown
together into irregular piles, but are spread out into level
sheets or great streams. It is not possible to ascertain their
thickness, but the water of small streamlets can be heard
trickling through the stones many feet below the surface.
The actual depth is probably great, because the crevices
between the lower fragments must long ago have been filled
up with sand. The width of these sheets of stones varied
from a few hundred feet to a mile; but the peaty soil daily