24 SEA AND LAND 



the rocky shore of tlic Athmtic coast, that is as far south 

 as New \'ork. beyond whicli point to the southward there 

 are no hard rocks facing the sea, is kept, by this ])ecuHar 

 action of tlie ice-floes, in good sliape to be assaulted by 

 the surges. , 



The reahu of nature exhibits a conflict of marvellously 

 related operations ; scarce any of her agents are able to act 

 with perfect freedom ; we therefore may not be surprised to 

 hnd that the work of frost and ice is much qualified by other 

 actions. We note among these conflicting conditions the 

 effect of the coast-line sea-weeds on the effect of frost. From 

 a point a little below high tide to the border of deep water 

 the rocky shore is usually covered with a dense growth ot 

 these lowl)- plants. The growth is generally so thick that we 

 cannot discern an\- part of the rock. When tiie tide has a 

 great rise and fall, as in the part of the coast al)Out the east- 

 ern coast of Maine and New Brunswick, a journey along the 

 shore at low water will give the student one of the most start- 

 ling impressions which his studies can afford him. The steep 

 cliffs are hung with a sombre arras of funereal hue made up of 

 those pendant fronds w^hich cover the rocks to a depth of a 

 foot or more. Observing these plants when they are floating 

 in the water, we perceive tliat the)' are buoyed up l)y numer- 

 ous air-bladders w liich develop in their tangled leaf-like foli- 

 age. These air-bladders, as well as the air entangled in the 

 mass of the matted stems which cover the rock, serve in a 

 measure to keep out th(; frost when the shore is bared at the 

 retreat of the tiele. 1 he coating acts as an e.xcellent non- 

 conductor, and by it our shores in high latitudes are in a 

 large measure protected from the destruction produced by 

 the expansion of freezing water in the rock crevices. 



