Granitic rocks named the Drongs, between Papa Stour and Hillswick Ness.]

[Illustration: Fig. 30.

Granitic rocks to the south of Hillswick Ness, Shetland.]

The granite rocks (fig. 29), between Papa Stour and Hillswick Ness
afford an example. A still more singular cluster of rocks is seen to the
south of Hillswick Ness (fig. 30), which presents a variety of forms as
viewed from different points, and has often been likened to a small
fleet of vessels with spread sails.[394] We may imagine that in the
course of time Hillswick Ness itself may present a similar wreck, from
the unequal decomposition of the rocks whereof it is composed,
consisting of gneiss and mica-schist traversed in all directions by
veins of felspar-porphyry.

Midway between the groups of Shetland and Orkney is Fair Island, said to
be composed of sandstone with high perpendicular cliffs. The current
runs with such velocity, that during a calm, and when there is no swell,
the rocks on its shores are white with the foam of the sea driven
against them. The Orkneys, if carefully examined, would probably
illustrate our present topic as much as the Shetland group. The
northeast promontory of Sanda, one of these islands, has been cut off in
modern times by the sea, so that it became what is now called Start
Island, where a lighthouse was erected in 1807, since which time the new
strait has grown broader.

_East coast of Scotland._--To pass over to the main land of Scotland, we
find that in Inverness-shire there have been inroads of the sea at Fort
George, and others in Morayshire, which have swept away the old town of
Findhorn. On the coast of Kincardineshire, an illustration was afforded
at the close of the last century, of the effect of promontories in
protecting a line of low shore. The village of Mathers, two miles south
of Johnshaven, was built on an ancient shingle beach, protected by a
projecting ledge of limestone rock. This was quarried for lime to such
an extent that the sea broke through, and in 1795 carried away the whole
village in one night, and penetrated 150 yards inland, where it has
maintained its ground ever since, the new village having been built
farther inland on the new shore. In the bay of Montrose, we find the
North Esk and the South Esk rivers pouring annually into the sea large
quantities of sand and pebbles; yet they have formed no deltas, for the
waves, aided by the current, setting across their mouths, sweep away all
the mater