242 



EARTH FEATURES AND THEIR MEANING 



A barrier series. The cross section of a barrier beach, like 

 that of a storm beach upon the shore, slopes gently upon the for- 

 ward side, and more steeply 

 at the angle of repose upon 

 the rear or landward margin 



mm/,mwmffiW/M!M/Mm (Fig. 265). The thinning 



wedge of shore deposits which 



FIG. 265. - Cross section of a barrier beach ^ barrier throws Out to S6a- 

 with lagoon in its rear. . . 



ward raises the level of the 



lake bottom (Fig. 266), and when coast irregularities are favor- 

 able to it, new spits will develop upon the shore outside the 



FIG. 266. Cross section of a series of barriers and an outer bar. 



earlier one, and a new bar, and in its turn a barrier, will be found 

 outside the initial one, taking a course in a direction more or less 

 parallel to it (Fig. 267). 



FIG. 267. Formation of barrier series and an outer bar in University Bay of 

 Lake Mendota, at Madison, Wisconsin. The water contour interval is fiye feet, 

 and the land contour interval ten feet (based on a map by the Wisconsin Geologi- 

 cal Survey). 



