140 LIFE OF THE PLEISTOCENE 



The multitude of lakes which dot the surface of Berrien, Cass, and Van 

 Buren counties, especially in the swampy area near the Dowagiac and St. 

 Joseph rivers, nearly all have marl deposits correlative with the later stages of 

 Great Lake history. Some of these may date from the glacial Lake Dowagiac 

 which had its outlet thru the Kankakee Valley, while others are relics of the 

 early stages of Lake Chicago when an arm extended into Michigan and up the 

 valleys of the Pawpaw and Black rivers (Plate XL VII, figs. 1,2). 



In the northwestern part of Cass County, and also partly in Van Buren 

 County, is a lake of considerable size known as Magician Lake. This body of 

 water empties into the Dowagiac River thru Dowagiac Creek. Swampy tracts 

 and old shore lines indicate that this lake was once considerably larger and 

 deeper. On the north shore, near the summer resort and about midway of the 

 lake, is an old embayment which is a swampy terrace about two feet above the 

 water line. The upper three feet are peaty and boggy; beneath this stratum 

 is a marl bed of unknown depth, which is filled with mollusks of the species 

 indicated below: 



Unto, fragments Physa walkeri 

 Sphaerium simile{ = sulcatum) " gyrina 



Pisidium compressum Planorbis antrosus 



" variabile " antrosus angistomiu 



" noveboracense " parvus 



" splendidulum " defledus 



adamsi affine " kirstttus 



Valvata tricarinata u Planorbis exactions 



A mnicola limosa Galba palustris 



" lustrica " galbana 



Paludestrina nichliniana " obrussa decampi 



Physa niagarcnsis " obrussa exigua 



" ancillaria Lymnaea stagnalis appressa 



Of the above 25 species and varieties, 5 species make up about 90 per cent 

 of the bulk of the material. These species are indicated in the order of their 

 abundance. 



Valvata tricarinata 

 Planorbis parvus 

 Amnicola lustrica 

 Paludestrina nichliniana 

 Galba obrussa decampi 



Lymnaea stagnalis appressa, Galba galbana, and Physa walkeri do not live 

 in the lake at the present time. This fauna may have migrated up the St. 

 Joseph River to the Dowagiac River and then up Dowagiac Creek. 



In the northeastern part of Berrien County, near the VanBuren County 

 line, is another lake of about the same area as that of Magician Lake. This 



61 Central carina almost absent in some specimens. 



