An associational study of Illinois sand prairie . e been isolated in theIllinois area, and have become distinct geographic varieties. Zlnoughhas been said to show that the sand areas of the Illinois Riv3r andsimilar sand deposits in other parts of the state are in reality lo-cal eastern extensions of the sand-hills of the middle region of theprairie province, or, what is nearer the true state of affairs, reliccolonies of sand-prairie, surrounded by the typical prairie grass andforest foiTmations of Illinois. In addition to the xerophytic relic colonies in Illinois, otherregions characterized b
An associational study of Illinois sand prairie . e been isolated in theIllinois area, and have become distinct geographic varieties. Zlnoughhas been said to show that the sand areas of the Illinois Riv3r andsimilar sand deposits in other parts of the state are in reality lo-cal eastern extensions of the sand-hills of the middle region of theprairie province, or, what is nearer the true state of affairs, reliccolonies of sand-prairie, surrounded by the typical prairie grass andforest foiTmations of Illinois. In addition to the xerophytic relic colonies in Illinois, otherregions characterized by severe physical conditions point toward theformer presence of the eastern extension of the arid prairie. Thewestern element gradually fades out tov/ard the east, and is best de-veloped in the most barren habitats. This element is well represen-ted in the flora and fauna of the sandy shores of the G^eat (1908 and 1909) records from the sand plain of Cedar Pointand Presque Isle, two sand spits in Lake Erie, such v/estern plants as. 15 Opuntia rafinesquii, Andropogon spp., Artemesia caudata, and Panicumvirgatus and scribnerianum. A larger numbGr of western plants, anda very considerable number of western animals, are found at the lowerend of Lake Michigan. Several sand regions occur in Indiana, themost extensive being the Kankakee River valley sand area. The prin-cipal sand areas in Illinois, aside from the I-Iavana and Lake , are the I-ankakee area, along the Kankakee and Iroquous riv-ers in eastern Illinois; the Amboy area, on the G-reen river, in LeeCounty, in v/hich very little sand-prairie is left; the Dixon area,in Lee County; the V/innebago County area, now mostly forested; andthe Oquawka area and the Hanover area along the Mississippi, in v/hichvery extensive tracts of sand-prairie are found. Western relics are found on the xerophytic sandstone outcrops irLa Salle County along the Illinois river, and in Ogle County alongthe Rock river. The
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