PERFORATED ROCKS. 
The powerful action of the sea upon rocks and cliffs is displayed in 
various ways. When the rocks are of granite or other hard stone, huge 
blocks are sometimes torn off or removed from their native beds, and 
thrown to a considerable distance on the land ; but when the rocks are 
of lime-stone or such comparatively soft material, they are often worn 
and perforated into a variety of remarkable forms. In some places the 
waves have scooped out caverns of great extent and beauty ; in others 
the limestone cliffs have been broken into columns of various shapes, 
frequently resembling towers, arches, &c. The wearing action of the 
waves is chiefly upon a space marked by the rise of the tide, and is 
greatest at the mean level of the sea. The limestone gives way to this 
incessant washing in angular fragments, which, after being worn down 
by the rolling of the surf, are finally deposited in beaches of shingle at 
an elevation corresponding to the highest rise of the tide. 
When one of Captain Franklin's exploring parties were sailing along 
the shores of the Polar Sea, they found that the cliffs and points of land 
in Franklin Bay presented many caverns and perforated rocks formed by 
the action of the waves, and ornamented by graceful slender pillars 
strongly resembling the windows and crypts of Gothic buildings ; these, 
"exhibited so perfect a similarity to the pure Gothic arch, that had 
nature made many such displays in the old world there would be but one 
opinion as to the origin of that style of architecture." 
In certain parts of a line of coast, masses of harder rock may occur, 
and these serve as a sort of rampart against the inroads of the ocean, 
which are wearing down the rest of the coast. In one of the Shetland 
Isles, the Atlantic, when provoked by wintry gales, batters against this 
sort of wall with all the force of real artillery, and by repeated assaults, 
the waves force an entrance for themselves. 
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No. 21.] 
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