Fig. 265.—Cross section of a barrier beach with lagoon in its rear.
A barrier series.—The cross section of a barrier beach, like that of a storm beach upon the shore, slopes gently upon the forward side, and more steeply at the angle, of repose upon the rear or landward margin ([Fig. 265]). The thinning wedge of shore deposits which the barrier throws out to seaward raises the level of the lake bottom ([Fig. 266]), and when coast irregularities are favorable to it, new spits will develop upon the shore outside the 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. 266.—Cross section of a series of barriers and an outer bar.
Fig. 267.—Formation of barrier series and an outer bar in University Bay of Lake Mendota, at Madison, Wisconsin. The water contour interval is five feet, and the land contour interval ten feet (based on a map by the Wisconsin Geological Survey).
