CONTENTS 



Introduction 23 



Physiography and Origin 24 



Climate 31 



Ecological Environment 34 



General Discussion 35 



The Vegetation 42 



Classification of the Plant Associations 46 



The Prairie Formation 47 



The Bunch-grass Association 47 



Successions from the Bunch-grass Association T] 



The PanicHin pseudopubescens Association 79 



Reversion to the Bunch-grass Association 83 



The Blowout Formation 84 



The Basin Association 90 



The Windward Slope Association 91 



The Blowsand Association 92 



The Deposit Association 95 



Successions between the Associations of the Blowout Formation 100 



Stabilization of the Blowouts and their Reversion to Bunch-grass 105 



The Hiidsonia Association 106 



Successions from the Blowout Formation 107 



The Blowout Thicket Association 107 



The Stenophyllus Association 108 



The Swamp Formation 109 



The Salix and SoUdago Associations 109 



The Polytrichum Association 112 



The Swamp Association 114 



Succession of the Prairie Formation by the Forest 116 



The Forest Formation 121 



The Black Oak Association 121 



Successions from the Black Oak Association 129 



The Bur Oak Association 129 



The Mixed Forest Association 135 



The River Dunes and their Plant Associations 139 



The Perched Dunes , 145 



Annotated List of Species 145 



Bibliography 171 



