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 SSOTANICAk 



TORREYA »^'"'«" 



Vol. 40 January-February, 1940 No. 1 



The Microfossils in a Pre-Kansan Peat Deposit Near 

 Belle Plaine, Iowa 



L. R. Wilson and R. M. Kosanke 



Interglacial deposits containing plant remains have been known 

 for a number of years, however few of these have been critically 

 examined by paleobotanists. Early studies of this nature dealt 

 entirely with macroscopic plant remains, but since the development 

 of micropaleontology, these deposits. can be further studied and 

 interglacial peats and silts can be examined for pollen and spores 

 and made to produce extensive assemblages of fossils. In the 

 Middlewest there exists but a single previously published paper 

 dealing with plant microfossils of Pre-Kansan peat. This work 

 was done by Nielsen^ in southeastern Minnesota. In addition to 

 examining the wood fragments which proved to be Picea and 

 Larix, a study was made of the peat pollens and spores. He records 

 species of Picea, Abies, Betulaceae, Acer rubrum, Lycopodium 

 complanatum, L. lucidulum, Juglans or Carya, Prunus (?), and 

 Junipcnis or Larix. The two last mentioned genera may not be 

 correctly identified since it is doubtful that pollens of these forms 

 exists as fossils in peat. Such an assemblage of plants as recorded 

 by Nielsen would suggest a forest of greater complexity than has 

 been indicated by younger interglacial plant deposits. 



In 1937 a portion of U. S. Highway 30, near Belle Plaine, 

 Iowa, was rerouted and extensive cuts were made through Nebras- 

 kan and Kansan glacial drifts. Lying between the two drifts 

 were found several exposures of Aftonian peat. These probably 

 represent a single deposit. The location of this deposit is in the 

 southwestern portion of York Township, in Tama County, Iowa. 

 The locality at which collections were made is 4.9 miles west of 

 the county line on U. S. Highway 30. The peat layer at the best 

 exposure was approximately six inches thick, and collections were 

 made through this at two inch intervals. The top-most collection 



^ Nielsen, E. L. A study of a Pre-Kansan peat deposit. Torreya 35: 53-56 ; 

 1935. 



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