BULLETIN Of THE GEOLOGICAL SOCIETY OF AMERICA 



VOL. 17, PP. 229-250, PL. 24 JUNE 8, 1906 



PALEOGEOGRAPHY OF SAINT PETEE TIME 



BY CHARLES P. BERKEY 



(Presented by title before the Society December 29, 1905) 



CONTENTS 



Page 



Introductory statement 229 



General character and distribution of the sandstone 230 



General stratigraphic position 232 



Origin suggested by writers 237 



Variability of the Saint Peter 238 



Variation more pronounced in minor details 238 



Thickness 238 



Purity 238 



Binding 239 



Structure 240 



Transition 240 



Unconformity 240 



Source of supply of material 242 



Structural character and texture 244 



Conclusions as to origin 246 



Physiographic changes 247 



Paleogeographic charts 249 



Summary 250 



Introductory Statement 



The Saint Peter sandstone is one of the most prominent Ordovicic 

 formations of the Mississippi valley. Because of its striking characters 

 it has attracted comment from almost every geologist whose work lay 

 within this territory. Most of them have been led to suggest an explana- 

 tion of its remarkable purity, or its apparent uniformity, or its structural 

 relations. Many have regarded the formation one of the most puzzling 

 of the region, the obscure problem being that of origin. 



The following study is primarily one of the physiographic conditions 

 represented in Saint Peter time. It has led to a comparative study of 

 this formation as described from many localities and bv many observers. 



XIX — Bull. Geol. Soc. Am., Vol. 17. 1905 



(229) 



