216 G. L. COLLIE WISCONSIN SHORE OF LAKE SUPERIOR 



the seat of shoals and incipient bars, the latter forminj^ at a distance 

 from the shore, but parallel to it. 



STACKS 



Isolated portions of rock are often cut off' from the parent cliff", espe- 

 cially on the exposed Apostle islands. The separation occurs chiefly 

 through wave action oi)ening and enlarging joint planes. The stack 

 may be separated but slightly from the parent mass, as is the case with 

 Lone island, or a wide channel may intervene, as in the instance of the 

 Little Manitou, which now stands 100 rods from its former connection. 

 All types of stacks occur, from the massive to the slender skerry or 

 drong. In some cases these pinnacle forms may be overturned and 

 only projecting })oints remain, such as are seen about the Sphinx. 



Summary 



The region described in this paper is that portion of the Wisconsin 

 shore of lake Superior which lies between point Detour and the Mon- 

 treal river. The shore, in part, is made up of a series of cliffs, either 

 composed of glacial debris or of Potsdam sandstone. In part the shore- 

 line is composed of a series of shore deposits, chiefly in the form of 

 bars, one of which has been thrown across the mouth of Chequamegon 

 bay, forming the longest and most important bar on lake Superior. A 

 group of islands, known as the Apostle islands, lie about Chippewa 

 l)oint, the northern projection of the state. These islands have resulted 

 from the drowning of pre-Glacial valle3'^s. The to})Ography of the main- 

 land is such as existed during }n'e-Glacial time, but is masked and 

 modified by glacial deposits. The mainland has rugged to[)ography, 

 especially in the interior, at a distance from the lake, and the lake is 

 bordered by a coastal plain a few miles wide, whose simple topogra[)hy 

 consists of a smooth surface without prominent elevations, m which 

 deep valleys are incised. The topogra])hy of the inner Apostle islands 

 is similar to that of the mainland, but the outer islands possess little 

 glacial debris and, in most instances, are mere flat tables of sandstone. 



In a general way, the lake level has gradually fallen since the Pleisto- 

 cene, but this has not been a continuous process, as fluctuations have 

 occurred. At present there is an ap})arent rise of the lake level, which 

 belief is sustained by two pieces of evidence: (a) The lower courses of 

 streams which empty into the lake have estuary features — they are 

 drowned streams — and (6) certain shore features, such as bars and spits, 

 are in process of rapid destruction. Apparently these formations were 

 made when the lake was lower, but with its rise they are being destroyed. 

 Wave erosion, especially on the exposed islands, has given rise also to 

 a series of erosion forms, such as caverns, coves, cliff's, and stacks. 



