layers of lava, besides eleven of volcanic m u d ; while at Horse
Pasture, on the same coast section, seventy layers of the former and
six of the latter, are plainly distinguishable.
These layers or strata vary considerably in composition and very
greatly in thickness, so that their examination next claims our attention.
The volcanic mud or laterite beds are in colour generally of a
yellowish brown passing into red, and where the non-intervention of
rubble happens their bright red edges show plainly the effect produced
by immediate contact with the burning hot lava. They vary
from eight or nine inches to several feet in thickness, and, where the
mud has fallen into irregular hollows or bowls in the surface of the
lava, they attain a greater thickness, exhibiting also quite a sedimentary
form of deposit. In many places this mud is to be seen
burnt as hard as a brick, while in others it is little harder than
-cheese; some extremely thick massive beds of it exist at the Eed
Quarry, Eock Cottage, &c., passing into the form of a vitrified
scoriaceous kind of slag, in which state it is a good deal used for
building purposes; being easily dressed for faced work, many of the
principal buildings in Jamestown are constructed of i t ; when
protected .by a thin coating of plaster or cement it is found to be
durable enough for such uses. Traces of small roots of plants occur
in some of these beds of laterite. I have noticed them especially near
Pierie’s Eevenge, but they are probably recent, and no fossiliferous
remains are found in them beyond embedded fragments of volcanic
rock, scoriae, and pumice, similar to those which make up the beds
of rubble. Some of these mud or ochre beds, as they are called,
exhibit the most brilliant red, yellow, and purple tints, which at
first sight are suggestive of fitness for colouring pigments; but no
use being made of them in this respect, their real value seems to
exist in forming indicatory records of subsequent disturbance, or
otherwise, in the general strata.
The rubble or agglomerate beds of small fragments of stones,
ashes, and cinders, which generally immediately overlie the mud
strata, range from two to three feet in thickness; the stones of which
they are made up are about two or three inches in size, in appearance
much worn and slightly rounded, and somewhat adhering
together. The face of the hill between Jamestown and Ladder Hill
aifords a good opportunity for inspecting these rubble beds. Generally
the lava has flowed over them without disturbing them much,