1900-1.] Physical Geology of Central Ontario. 139 



PHYSICAL GEOLOGY OF CENTRAL ONTARIO.* 

 By Alfred W. G. Wilson. 



(Read 20th April, igoi.) 



CONTENTS. 

 INTRODUCTION. 

 Location. 



Historical References, and Sources of Information. 

 Resume. 



TOPOGRAPHY OF THE PRE-SEDIMENTARY FLOOR. 

 Diverse Character of the CrystalHnes. 

 Even-topped Character of the Uplands. 

 Dissection. 

 Gradients. 

 Three Problems Stated. 



First Prqblem. — The Pre-Sedimentary Topography. 

 Inliers. 



Outliers. ' 



Conclusions. 

 Examples Elsewhere. 



Second Problem. — Date of Erosion. 

 Third Problem. — Conditions of Erosion, 

 Summary. 



THE PALAEOZOIC SERIES. 



A Question of Correlation. 



Sandstones. 



Arkose. 



Black River and Later Formations. 



Summary of the Paleozoic History. 



POST-CARBONIFEROUS HISTORY. 



Mesozoic, Cainozoic, and Early Pleistocene Epochs. 

 Measure of Erosive Work. 



* This paper was written as a thesis for the Doctorate of Philosophy at Harvard University, and was 

 presented in May, igoi. 



