Document Type



Land snails, Gastropoda, Loess Hills, Missouri Alluvial Plain, Pleistocene, Holocene, recent, Iowa.


The Loess Hills and Missouri Alluvial Plain landform regions of western Iowa were surveyed for molluscs in July and August, 1982. We focused on the modern fauna and that of the late Woodfordian (Wisconsinan) Peoria Loess, but a few localities with older and younger Pleistocene and Holocene faunas were also collected. Systematic bulk samples were taken at 95 localities: faunal lists for 75 are included herein. The modern land snail fauna comprises 40 species, most of which are small, drought-resistant cosmopolitan or Interior Province forms. One, or possibly two, Rocky Mountain forms survive as relicts. The modern fauna is depauperate in comparison to that of eastern Iowa. No definite endemic taxa were noted, but several succineid taxa require further study. The Peoria Loess fauna is more diverse and heterogeneous than the extant in its affinities. The total (47 species) includes major Interior Rocky Mountain, Northern, and Midwest Biome components as well as widespread taxa. The Interior element has many more deciduous forest taxa than currently survive. The poorly-known Holocene fauna (34 species) comprises mostly cosmopolitan and Interior taxa, with a few Rocky Mountain or extinct holdovers. In the Loess Hills region, diversity increases pronouncedly from north to south for both Peoria Loess and modern faunas. No clear trend is evident for the Missouri Alluvial Plain. Peoria Loess faunas are most diverse within a mile of the west bluff edge: diversity declines rapidly at more interior easterly sites.

Publication Date

September 1986

Journal Title

Proceedings of the Iowa Academy of Science





First Page


Last Page



©1986 Iowa Academy of Science, Inc.



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