120 LIFE OF THE PLEISTOCENE 



Amnicola limosa Galba reflexa 



" lustrica " paluslris 



" cincinnaticnsis obrussa decani pi 



The absence of detailed information relative to the stratigraphy of the 

 Milwaukee strata renders the correct placing of the deposits observed by 

 Slocum very difficult. The peat stratum may record a low water stage or 

 land surface, probably of early date, perhaps between the Toleston and 

 Hammond stages. There may have been a small bay in the region now oc- 

 cupied by the Milwaukee and Menominee rivers during one of these stages. 

 Alden 14 describes marsh deposits at the confluence of these two rivers at 

 depths of 20 to 53 feet below the level of Lake Michigan, indicating that at 

 some time the waters of the lake fell very much lower than during the stages 

 which built up the beaches. Alden believes this period of erosion to have 

 followed the Calumet stage. The writer believes that the low water period 

 following the Toleston (as outlined in the previous chapter) was the time of 

 this very low water stage and that there was a period of dry land. The 

 Marsh deposits beneath beach gravel at Kenosha evidently underlie the 

 Englewood beach (Nipissing stage). 



The shells mentioned by Whittlesey 15 as occurring in yellowish compact 

 clay and hardpan 12 to 24 feet above the level of the lake at Milwaukee 

 probably came from the same horizon as the shells collected by Mr. Slocum. 

 Five species are identified. 



Planorbis campannlatus 



Paludina decisa {—Campcloma decisa) 



Melania depygis ( = Goniobasis dcpygis). This was probably livesocns rather than 



dcpygis. 

 Limnaea desidiosa ( = Galba obrussa) 

 Cyclas similis {—Sphaerium sulcatum) 



Recently, Mr. J. R. Ball, of Northwestern University, has brought to my 

 attention a deposit containing molluscan shells in the ravine of a small creek 

 entering Lake Michigan at Kenosha, Wis. which possibly belongs to the same 

 stage as the marsh deposits recorded above by Alden. Mr. Ball describes 

 the locality as follows: "The small creek (Pike Creek) has a rather wide valley, 

 showing numerous cut-offs and abandoned meanders, and, at several turns in 

 the present stream, where banks ranging from three to five feet in height have 

 been cut out, the enclosed specimens were found. They were not very abun- 

 dant and are not to be seen elsewhere than where found, viz., about one foot 

 or ten inches from the present valley floor. They are found in a rather 

 sandy formation, darkly stained with organic matter, which overlies a clay 

 formation which weathers in rectangular fashion, and which is also stained 



14 Milwaukee Folio, p. 9. 



16 Bull. Geoi. Soc. Amer., XXII, p. 215. 



