170 
POPULAR SCIENCE REVIEW. 
slope down to tlie level of low-water, beyond which, the 
inclination is often very gentle. If the coast is rocky, the 
warfare of the waves and the stubborn resistance offered to 
their advance is marked by many a breast-work or projection, 
sometimes by an isolated fort (or sea-stack), which has with- 
stood the assault longer than its companions (see plate) ; but 
when the coast is formed of some softer material, such as clay 
or shale, the shingle beach is generally bounded by a bank pre- 
senting few irregularities of outline. How varied is the aspect 
of our coast at different points, it is almost unnecessary to 
remark ; yet it is essential to the proper understanding of our 
subject that this be borne in mind, because similar variations 
are to be found in the ancient coast-lines and raised beaches 
of which we shall come to speak presently. Along the coasts 
of Devon and Cornwall, the highlands of Wales and Scotland, 
and the north and west of Ireland, walls of massive rock 
descend sheer down into the surging waves. In other places, 
as in Lincolnshire — but on a larger scale in the Netherlands 
— -the descent from the land to the sea is so gradual, that, 
except where the boundary line has been rendered distinct 
by art, the passage from the domain of the land to that of 
the sea could only be recognised by the absence of vegeta- 
tion. Other parts of the coast, however, partake of an in- 
termediate character. Here the limits of tidal action are 
defined by a low line of cliffs, or a steep bank and a slightly 
shelving strand. These different forms of coast-fine have an 
intimate relationship to the strength and arrangement of the 
rock or formation, and the configuration of the interior. 
Where the chalk of Mamborough Head, the South Downs, 
and the Isle of Wight, rises into hills inland, it terminates in 
the white walls of our “ Albion/'’ while the softer clays and 
sands of Sussex and Essex subside into a featureless shore. 
All the while that the land remains at a certain level the 
sea is at work, sapping and mining the shore, and, by its 
currents, carrying away the materials to be spread over its 
bed. The strand has a general tendency to assume the form 
of a flat plain, on account of the levelling action of the 
breakers, which is confined to a vertical limit of a few feet. 
Sometimes deep fissures are hewn in the rocks of the coast, 
along lines of jointage ; in other cases, isolated pillars, or 
masses of rock of every conceivable shape are found, and, 
less commonly, caves are hollowed out. Fingalfis Cave, hewn 
out of cliffs of basaltic columns, is a well-known example ; and 
if the western coast of Scotland were suddenly elevated, perhaps 
thirty or forty feet, the entrance of the cave would be at the 
side of an inland cliff, with a terrace stretching from its base 
to the shore. This cliff would mark the present limit of tidal 
