548 



^ 



It 



CHAPTER XXI. 



ACTION OF TIDES AND CURRENTS — continued. 



ft 



f 



THE SEA AT THE MOUTHS OF THE 



CHANGES 



IN THE ARMS OF THE RHINE— PROOFS' OF SUBSIDENCE OF LAND— ESTUARY 

 OF THE DIES BOSCH, FORMED IN 1421— ZUYDER ZEE, IN THE THIRTEENTH 

 CENTURY— ISLANDS DESTROYED— DELTA OF THE EMS CONVERTED INTO A 

 BAY— ESTUARY OF THE DOLLART FORMED— ENCROACHMENT OF THE SEA ON 

 THE COAST OF SLESWICK— ON THE SHORES OF NORTH AMERICA— TIDAL 

 WAVE, CALLED THE BORE— INFLUENCE OF TIDES AND CURRENTS ON THE 

 MEAN LEVEL OF SEAS— ACTION OF CURRENTS IN INLAND LAKES AND SEAS 

 BALTIC-CAMBRIAN DELUGE— LAKE ERIE-STRAITS OF GIBRALTAR-NO 



UNDER-CURRENT THERE— VARYING DEPTH AND TEMPERATURE OF THE MEDI- 



TERRANEAN. 



yf the sea at the mouths of 



■The 



British coast considered in the preceding chapter offered no 



example of the conflict of two gi 



influx, on the one hand, of a river draining a large continent, 

 and on the other, the action of the waves, tides, and currents 



of the ocean. But when we 



the Straits of 



Dover to the Continent, and proceed north-eastwards, we 



dmirable 



ocean and the Rhine are opposed to each other, each dis- 



_ _ -- - . - i • • 



Holland , 



form 



There 



was evidently a period when the river obtained the ascen- 



and 



coast and set of the tides were very different ; but for the last 

 two thousand years, during which man has witnessed and 

 actively participated in the struggle, the result has been 

 in favour of the ocean ; the area of the whole territory hav- 



more circumsci 



ficial barriers have given way, one after another ; and many 





• 



