KORTII AMERICAN GEOLOGY. 229 



tbe region where there is neitlier erosion nor deposition, but transpor- 

 tation only, tlie shore drift takes the form of a heacl!, and if the land 

 is gently inclined a lagoon is separated behind the beach, which is 

 then (tailed a barrier. Points of land are usually eroded by waves, 

 while bays are filled or partitioned olf by bars; the waves of a lake 

 thus tend to straighten its shores. Other shore features treated are 

 the delta, whose anatomy as well as morphology is described, and the 

 shore wall, a feature resulting in cold climates from the expansive force 

 of ice. 



The topographic elements constituting sliores have sometimes been 

 confused with similar elements of different origin, and the criteria for 

 discrimination are therefore discussed. A sea-cliff is compared with 

 cliffs resulting from the unequal hardness of strata, from lateral wear 

 by streams, from faulting, etc. Shore terraces are compared with ter- 

 races arising from alternations of hard and soft strata, stream terraces, 

 fault terraces, etc. Barriers and other shore structures constituting 

 ridges are compared with moraines and osars.* 



U. S. Geol. Survey, Fifth Auuual Keport, pp. G7-123. 



