228 



PHYSICAL GEOLOGY 



Fiord Coasts. — The coasts of high, glaciated regions are characterized by narrow, 

 branching bays of great depth (p. 226, and Fig. 150), with precipitous, almost vertical 



sides, called fiords (p. 166). 

 It has been shown (p. 167) 

 that fiords are valleys 

 greatly deepened by glacial 

 erosion, which have prob- 

 ably been drowned by a 

 sinking of the land. 

 Fiords occur only in high 

 latitudes. 



Deeply Indented Coasts 

 in Non-glaciated Regions. 

 — In northwestern Spain, 

 Brittany, Ireland, and 

 elsewhere are fiord-like 

 coasts which, however, 

 have not suffered from 

 glacial erosion. These 

 funnel-shaped bays were 

 produced by the drowning 

 of deep valleys formed by 

 stream erosion. Such in- 

 dentations differ from 

 fiords, not only in their 

 origin, but also in their 

 V-shaped cross section and 

 in the fact that they gradu- 

 ally deepen seaward, while 

 the deepest portions of 

 fiords are some distance 

 inland. 



Coasts of Slightly Sub- 

 merged Coastal Plains. — 

 The coastal plains of the 

 United States have been 

 described (p. 224) as re- 

 cently raised portions of the ocean bottom. After having been cut up to some 

 extent by erosion a slight submergence occurred, which drowned the valleys, thus 

 forming Chesapeake Bay, Delaware Bay, etc. 



Proofs of Elevation and Depression. — Although the coast of Maine 

 is quite typically that of a region of submergence, there is evidence 

 that considerable elevation followed the period of greatest sinking. 

 This evidence is to be seen in the marine clays which are found above 

 the present sea level, as well as in the abandoned shore lines which 

 arc now far above the tide. 



Fig. 221. — Portion of the east coast of the Adriatic. 

 The folds of the rock largely determine the direction of 

 the straits, islands, and peninsulas. 



