environmental history  
Left: yellow warbler.  Photograph by the U.S. Fish and Wildlife Service.  Click on photograph for link to the source.
introduction geography geology cultures ecosystem conservation  

Project goal:  Help sustain the natural resources and protect cultural resources of the Driftless Area.

Driftless Area



The Pleistocene Epoch was a time of enormous animals and very tiny animals. The now extinct wooly mammoth and mastodon roamed the tundra and boreal forest habitats flanking the Late Pleistocene ice sheet that advanced all the way into Iowa during the peak of the glaciation. These large mammals were a source food for the PaleoIndians once they arrived in North America.  Mastodon fossils have been found all the way north to Alaska.  There were other large mammals that went extinct at the end of the Pleistocene including camels, horses, ground sloths, giant beavers, and saber tooth tigers.  Click on the image to the right for more information on Pleistocene animals (Illinois State Museum).  


Spruce forests developed on what was once tundra habitats along the leading edge of the Pleistocene glaciers as the ice sheet retreated some 13,000 years ago from around the Driftless Area. Warming climates that followed supported boreal forests including tree species like the yellow birch and Canadian yew that can still be found on the algific slopes of the Driftless Area. Forest succession and warmer conditions of the later Holocene supported oaks, hickories, and sugar maples. The warmer climate also supported vast prairies with patches of oak savannas on some of the southern hillsides and the flat lands surrounding the Driftess Area. The forests in the hilly regions and along rivers matured to climax communities and the grasslands supported large herds of bison until the wild herds were decimated some 125 years ago from habitat loss and overhunting especially by European settlers.


There were also many species of tiny land snails found among the mosses, liverworts, and tree leaves of the cool moist floor of the Pleistocene boreal forests. These land snails help breakdown the detritus and organic matter to recycle nutrients. The lands snails from the Pleistocene Epoch were thought to be extinct and were only known by fossils collected in the glacial drift south of the Driftless Area. Naturalists working in the Driftless Area during from the early through the mid 1900's discovered living species of the Pleistocene land snail species on the algific slopes. These land snails were probably able to colonize the cold climate habitat in the Driftless Area by being transported on animals moving from the shrinking boreal forest in the south to the developing temperature deciduous forest with cold slopes of the Driftless Area. The Driftless Area now serves as refugia for the glacial relict species some of which are not found anywhere else in the world. Land snails are among the most imperiled animal species on the planet.

The Driftless Area is a biodiversity hot spot for temperate and cold climate land snails. There are about 30 species of land snails in the Driftless Area.  Other biological hot spots for land snail biodiversity are in the tropics. The land snail assemblage in the Driftless Area includes more common species for forest habitat and some State and federally listed endangered species that depend on the cold climate conditions. The endangered Iowa Pleistocene snail (Discus macclintocki) is the largest (5 - 7 millimeters) and most known of the rare snail species. Other and little known State endangered and Federal species of concern include the Brairton Pleistocene snail (Vertigo briarensis), Iowa Pleistocene succineid (Novisuccinea b sp.), and the Iowa Pleistocene vertigo (Vertigo iowaensis). Another genus of tiny land snails that occurs in the Driftless Area is Catinella. The frigid ambersnail (Catinella gelida) found in the Driftless Area was recently considered for listing as endangered under Federal law. The frigid ambersnail was not listed because the taxonomy of this species is poorly defined. The vertigo snails (image to right), succineids, and ambersnails are a wide ranging and diverse group of tiny (1 - 2 millimeters) land snails with high adaptive radiation and confusing phylogenies.  There are likely many subspecies and taxonomic synonyms. 


Left: enlarged view
Right:  four times actual size

There are variety of disjunct and climate relict species (tundra and boreal species of refugia during range shifts) in the Driftless Area.  Some of these taxa only occur in the Driftless Area.  The photograph to the right shows golden saxifrage (Chrysosplenium iowense) mixed in with mosses growing on talus of an algific slope of the Driftless Area.  The golden saxifrage is only known from 15 algific slopes in the Driftless Area and from the main population now in the boreal forests of Canada.  This moist soil cover with detritus from the leaves support the Pleistocene land snail community.  We can learn about species response to climate change and global warming by studying these climate relicts.  

Human demand for timber cut down the old growth trees of the climax forests. The limestone and sandstone are mined for construction materials, road materials, and lately for natural gas fracking operations. Today the forests of the algific slopes are restricted to public lands and along the inaccessible narrow and steep bluffs on private lands. It is necessary to work together if we are to sustain the remaining habitats and restore degraded habitats.




Iowa Drifltess Area land snail surveys
Minnesota Driftless Area land snail surveys
Status assessment glacial relict snails
Frigid ambersnail status review
Pupillid land snails
Evolutionary patterns and processes
Land snail community diversity
Pleistocene fossil snails

Image library

Search for Imperiled Species on the
International Union Conservation of Nature
Red List


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  2011 All Rights Reserved    Design, Information, Photographs unless otherwise linked are by Mike Joe Coffey