ACTION OF FROST AND JCE 23 



storms have rent from the chfl are hrouL^ht to a size where 

 the lesser waves can toss them about. In this wa\- the 

 frosted shores are able to present steeper cliffs than those 

 which are not thus affected, and when all the work has to be 

 done by the action of the waves with such sliL;ht assistance 

 as the slow chemical decay of the rocks may afford. 



While the expanding- action of the frost is doubtless most 

 efficient in wearing back tlie face of rock-clifTs, the effect of 

 the ice which gathers along the shore is probably of vet 

 more importance. In all times of comparative calm, when 

 the temperature is low enough rapidly to freeze the water 

 next the shore, the ice gathers in extensive fields and often 

 becomes heaped up by the drifting of these areas until it 

 has a thickness of ten feet or more. When the tide is low 

 the stones become fixed in the mass, and by the current, 

 when in this position, are driven as rasping engines against 

 the base of the cliff. In this way the ice-imprisoned stones 

 continue the work which the w'inds have begun, and accom- 

 plish a great deal of abrasion. The most important in- 

 fluence of the ice-fields, however, is to clear awa\' from the 

 shore the excess of detritus which the waves may have accu- 

 mulated there. The reader may often observe points where 

 this mass of stones is so great that the waves are fended 

 from the cliff which they are assailing, except where the 

 tide lifts the surface of the sea to its greatest height. Thus 

 it may be, for a few hours in the twenty-four, tiiey may 

 strike against the base of the ocean cliff. A single heavy 

 and enduring frost ma\- so ImucI this detritus into the ice- 

 field that the tide, aided by a strong wind from oft the 

 shore, can drift it all away to be dropped on the bottom of 

 the deep sea possibly miles froni the coast-line. Nearly all 



