232 Proceedings of the Ohio State .leademv of Science 



All this material is being distributed likewise by the water. 

 Beach ridges represent the ascendency of the work of water 

 moving on-shore over that accomi)lished b}' the water moving 

 outward, that is, the under-tow. Whenever the dash of oncoming 

 waves drives material up the slope beyond the effective reach of 

 the under-tow. that material becomes part of the beach ridge. 

 The ridges represent the work of unusually strong and more 

 directly on-shore movements ; an ec|ually powerful on-shore 

 wave, striking the coast oblicjuely, is not so effective in construct- 

 ing ridges. Since the beach ridge, then, represents a diff'erential 

 of these quite opposing movements of water, it follows that the 

 shape of this ridge is also the result of this difference. The un- 

 dertow cannot carry any save the smaller bits of rock, and only 

 the finer portions are carried very far off-shore. Material in 

 suspension is always the finest product of destructive work and 

 will be taken farthest from the shore line. The front slope of 

 a beach ridge has a long gentle gradient, save at the edge of the 

 water, wdiere, for a short horizontal distance, the angle is 

 sharper ; the back-slope often has a short, sharp angle, and stands 

 more conspicuously above the coast (figs. 2, 3). 



When the waves do not strike the shore directly, the oblique 

 movement sets up an along-shore drift; this along-shore drift is 

 a more active distributing agent when the coast is parallel to, 

 or but slightly transverse to, the direction of the prevailing 

 winds. The outlines of these high-level lakes were in general 

 concentric with the present Lake Erie, the shore of which is well 

 exposed to the sweep of the prevailing west winds. It is due to 

 this relationshi]:) that headlands have been removed and their 

 products distributed to the east. 



Where an angle of water extends into the land, we gener- 

 ally find a spit gradually growing out across this reentrant from 

 its windward side. The along-shore movement of water dis- 

 tributes material in a straight line unless some stronger force 

 tends to deflect the line of deposition. Such a deflecting force 

 is present when we find translatory waves passing landward 

 through the deepening area of the bay ; then the spit is bent in- 

 ward in the shape of a hook. As the height of the spit increases 



