220 



THE NATURE BOOK 



ablv have long since disappeared. It 

 forms, however, the rocky backbone of 

 the island, and every visitor to that 

 delightful spot knows the beautiful tower- 

 ing chalk cliffs of Freshwater, that beat 

 back the hungry wa\'cs, and the Needles 

 rocks, that once formed part of the island. 

 If we travel down to the Land's End 

 during the winter months and witness 

 some of the terrible storms that sweep 



cliffs is constantly going on, there is a 

 certain amount of give-and-take, for in 

 situations along the coast where the cur- 

 rents do not run so fast, or where they 

 set more towards the shore, sand and 

 di-hris is constantly accumulating, so 

 that fresh land is forming. This is seen 

 on flat, sandy shores that are bounded 

 landwards by the low sand-hills or 

 " dunes." These " dunes " are formed 



A GATHERING STORM ON THE DORSET COAST. 



along its cliffs, we soon realise that but 

 for its iron-bound coast of hard granite 

 and metamorjihic rocks, against which 

 the angry waves hurl themselves in vain, 

 Cornwall must long since have disappeared 

 beneath the Atlantic. 



Where the set of the current is strong, 

 the dihris torn from the cliffs and pounded 

 b}' the waves into fine sand and shingle is 

 carried away, the finer particles out to 

 sea, where they accumulate and form 

 treacherous, shifting sandbanks, like the 

 Goodwins ; while the coarser pebbles 

 form the ever-moving pebble beaches, of 

 which the Chesil Bank near Portland is a 

 familiar and remarkable example. The 

 waves are hard at work striving to sweep 

 away Portland, which forms a natural 

 groin protecting the Dorset coast, and 

 once the work of destruction is com- 

 pleted, the coast of Dorset will ha\'e to 

 face the full fury of the storm-lashed 

 wa\'es. 



Although the work of wearing away the 



when the tide is out and the wind is 

 blowing off the sea. The wind then lifts 

 the sand as it dries, and carries it land- 

 wards until it reaches the low scrub of 

 reeds and grasses which grows just be- 

 yond the reach of the waves. Here the 

 advance of the sand is arrested, and it 

 falls amongst the stems of the reeds and 

 grasses. 



Gradually the sand accumulates and 

 covers the binding mass of vegetation, 

 until a long, low ridge of dunes is formed. 



In situations where the waves break 

 upon the shore obliquely, we may watch 

 them at their work grinding down into 

 pebbles the hard fragments of rocks 

 which they have torn from the cliffs. 

 E\'ery incoming wave drives forward 

 obhquely the shingle composed of more 

 or less smooth, rounded rocks of all 

 sorts of sizes ; and these, as the wa^■e 

 retreats, seem to give chase, rolling down 

 ])erpendicularly to the shore line, after it. 

 Rows of wooclen piles, or groins, are fre- 



