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CONTENTS. 



Letter of transmittal xv 



Abstract of volume xvn 



Chapter I. — Introduction - 1 



Chapter II. — Physical features 7 



Chapter III. — Outline of time relations or glacial succession 19 



Chapter IV. — The Illinoian drift sheet and its relations 24 



General statement 24 



Relation to outlying and underlying drift . . 24 



Relation to the Iowan drift sheet 24 



Culmination of the Illinois lobe at the Illinoian stage 25 



General aspects of the Illinoian drift sheet 25 



Extent of its exposures 25 



Topographic expression 26 



Thickness of the drift 27 



Structure of the drift 27 



Gumbo (?) - 28 



Sections of the Illinoian drift... 33 



The drift border 34 



Distribution 34 



Topographic expression — 38 



Structure of the drift border 40 



Character of the out wash 70 



The ridged drift of the Kaskaskia Basin -.. 71 



Buffalo- Hart moraine 74 



Eskers or gravelly ridges of northwestern Illinois 76 



Leaf River or Adeline esker 76 



Hazelhurst esker 78 



Garden Plain esker 79 



Pecatonica esker system .1 80 



Cedarville belt 81 



Orangeville belt 81 



General observations 82 



Transported rock ledges 82 



Glacial strife 84 



Effect of the Illinoian ice invasiou on the outer-border drainage 89 



Temporary displacement of the Mississippi River 89 



Changes of drainage in southwestern Indiana 97 



Pleistocene deposits beneath the IUiuoian till sheet 105 



Kansan till 105 



Pre-Illinoiau till and associated deposits 107 



Silveria ( ?) formation and other silt deposits Ill 



Chapter V. — The Yarmouth soil and weathered zone 119 



Weathering of the buried Kansan drift 119 



Buried soil, peat, etc 120 



Erosion of the Kansan drift sheet 121 



Organic remains 123 



C 



