6 CONTENTS. 



Page. 



Chapter III. — Drainage systems 82 



Section I. — Ohio Biver system 82 



Ohio River 82 



Rate of fall 82 



Effect of rock resistance on size of valley 84 



Rock islands in the valley 84 



Upper Ohio or old Monongahela system : . 88 



The old divide 88 



The northward outlet 94 



Extent of the old Monongahela system ' 98 



The old divide on the Allegheny 98 



Middle Ohio or old Kanawha system 100 



The northward outlet 101 



Deflections of drainage - 104 



Lower Ohio system - 109 



Probable extent 109 



Relation to topographic features 1 109 



Tertiary fluvial deposits Ill 



Gradation plains below the level of the Tertiary deposits 113 



Drainage changes near Cincinnati 116 



Relation of the glacial deposits to the erosion features of the Ohio Valley 118 



On the Lower Ohio 118 



On the Middle Ohi. i 119 



On the Upper Ohio 121 



Allegheny River 125 



Rate of fall 125 



Rock floor. 127 



Description of the valley 128 



Old Upper Allegheny drainage system 129 



Old Middle Allegheny drainage system 132 



Old drainage between the Upper and Middle Allegheny drainage systems 138 



Lower Allegheny and its tributaries 143 



Beaver River , 148 



Little Beaver River 152 



Muskingum River 153 



The old westward outlet 155 



The present line of discharge 156 



Deposits on the lower course of the Muskingum 157 



Striated blocks in Muskingum Valley near McConnelsville 158 



Extent of the old Muskingum drainage basin 158 



Drainage tributary to the westward outlet 160 



Changes in Owl Creek drainage basin 160 



Changes in Clear Fork of Mohican Creek 162 



Changes in other headwaters of Mohican Creek 162 



Killbuck Creek 165 



The old Upper Tuscarawas drainage 165 



Hocking River ., 169 



The present drainage 169 



Changes in the headwater portion _ 169 



Raccoon Creek 172 



Symmes Creek 173 



Little Scioto River 173 



Scioto River 174 



The headwater portion 175 



The lower course 177 



