, a crystallization, of which, by itself, it is not
susceptible.

The garnet is found in Bohemia, Ceylon, and other countries; but the
chief mart formerly being Sirian, the capital of Pegu, the best are
often denominated Sirian garnets. The colour most esteemed is blood or
cherry red, mixed often, however, with blue, forming tints of crimson,
purple, and reddish violet; or orange red and hyacinth brown. The Sirian
garnet is of a violet colour, which, in some rare specimens, makes it
compete with the amethyst, from which it is to be discriminated by the
disadvantage of losing its brilliancy, and acquiring an orange tint by
candlelight. Distinct from all other garnets, it preserves its colour
unmixed with the common black tinge, unassisted by foil, even when
thick. _Course garnets_ are used as emery for polishing metals, and by
lapidaries. They are found in Ireland, in Norway, and many other
countries.

* * * * *

GEOLOGICAL CHANGES EFFECTED BY THE SEA.

(_From the preceding work_.)

_Why are certain formations called marine?_

Because they result from continual deposits of shingle and sand, as may
be seen on the flat coast of our eastern counties. In this manner, at
Lowestoffe-Ness, as well as at Yarmouth, the sea has erected a series of
natural embankments against itself. The present extent of land thrown up
by the sea, and out of the reach of the highest tides, is nearly three
miles long, projecting from the base of the original cliff to the
distance of 660 yards at the Ness. The respective lines of growth are
indicated by a series of small embankments, perfectly defined. Several
of these ridges have been formed within the memory of men now living. A
rampart of heavy materials is first thrown up by a violent gale from the
north-cast. Sand is subsequently blown over, and consolidates the
shingle, and the process is completed by marine plants taking root and
extending their fibres in a kind of net-work through the mass. In
process of time the surface becomes covered with vegetable mould, and
ultimately, in many cases, is productive of good herbage.[5]

[5] From a Communication to the _Philosophical Magazine_, by Mr.
R. Taylor.

_Why are shingle beaches formed by heavy gales?_

Because every breaker is more or less charged with the materials
composing the beach; the shingles are forced forward as far as the
broken wave can reach, and, in their shock against the beach,