r.KACMKS 21 



Barrier hearh. — Hiirrier beaches occur chiefly on Madeline i.shmd, tlie 

 hirgest member of the Apostle group. They have been thrown across 

 tlie bays between the more prominent promontories. They only occur 

 where tlie neighboring clills are composed of glacial drift, and thus fur- 

 nish an abundance of transportable material. The normal type is a 

 broad low bar, chiefly of sand, cutting off lagoons which have become 

 more or less filled. The best example is the barrier beach connecting 

 the "Old Mission " with the town of La Pointe. These beaches have 

 helped greatly in smoothing the originally irregular shores of Madeline 

 island. 



Cliff beach. — This t3^pe of beach is formed at the base of the long line 

 of clay cliffs between the Bad river and the Montreal. A narrow bench 

 is cut out at the base of the cliff, and here the coarse debris is deposited 

 in a characteristic way. The shoreline in this region is quite straight. 

 There are few pockets in which debris can be gathered. Much of the 

 material derived from the cliffs is too coarse for ready transportation. 

 Under these conditions the coarse shingle and boulders are thrown up 

 against the face of the cliff. The base of the deposit rests on the narrow 

 bench at the foot of the cliff. The beach thus formed presents a steep 

 front, exceeding 30 degrees, as a rule. The coarse materials composing 

 it are piled high against the cliff face, frequently from 12 to 15 feet. The 

 coarse debris is packed firm by the repeated blows of the waves. The 

 beach is usually so massive that it is thrown across the courses of streams 

 without being disturbed by their presence, the water of the streams only 

 entering the lake by seei:>age through the coarse gravels. Occasionally 

 pockets occur in the shoreline of the cliffs, and in such cases the char- 

 acter of the beach changes. Finer materials obtain a foothold under 

 such circumstances, and the beach is not built up as high, nor are its 

 slopes as steep. 



Storm beach. — The storm beach is found chiefly on the exposed bars, 

 where the sand is shifted to and fro by each storm. Temporary ridges 

 of sand accumulate, which are several rods in length. Usually the storm 

 beach is attached at one end to the parent beach, the other end being 

 free. These beaches are constantly forming and disappearing, according 

 to the violence of the storm and the varying direction of the wind. 



SHOALS 



The streams which enter the lake form delta deposits, which are greatly 

 modified by wave and current action. Deltas of regular form are not 

 built up in the face of the lake storms. The deposits should be desig- 

 nated as shoals rather than deltas. The debris is scattered about widely 

 by waves and currents. It is only here and there that sufficient mate- 



XXXI— Bull. Geol. Soc. Am., Vol. 12, 1900 



