64 



The Saint Peter Sandstone. 



[Paper D.'] 

 THE SAINT PETER SANDSTONE.* 



F. W. Sardeson. 



Introduction 64 



Thickness 65 



Geographical Distribution 65 



Geological Distribution 66 



Structure 68 



Lithologic Characters 67 



Paaeontologic Characters 68 



Discovery of Fossils 68 



Condition of Preservation. 69 



Description of Species 70 



General Discussion of 79 



Physical Relations 80 



Straligraphic Position 82 



Correlation 83 



Origin (Theories) 84 



Bibliography 87 



INTRODUCTION. 



The name of this formation was written Saint Peter's 

 Sandstone by its author, Dr. Owen, and some geologists 

 still retain that form of the name. The amended form, Saint 

 Peter, has however long been used, and is preferred. The 

 name was adopted by Owen because of the good exposure 

 that is situated at the mouth of the Minnesota river, which 

 last in Owen's time was called the Saint Peter's. The city 

 that was of the same name as the river formerly, is now 

 called Saint Peter. 



The type exposure of the formation was chosen because 

 of its situation at the military post, Fort Snelling. It is 

 typical, and a description of it sufficed to enable geologists 

 to recognize the same formation at any othjer of the many 

 exposures, which occur over a large area. Even the earliest 

 descriptions ol this sandstone are free from confusion, both 

 because its very peculiar characters excited close attention, 

 and because those characters are so persistent that recog- 

 nition of the formation was nowhere difficult. In fact, 

 owing to the persistency of its characters, descriptions of it, 

 although drawn from different regions, are monotonously 

 similar. The little variation that does exist seems to be 

 intended to relieve monotony rather than add to scientific 

 knowledge. The formation is noticeably lacking in mineral- 

 ogical, petrographical, stratigraphical and palseontological 

 diversity. 



* Owing to unavoidable delay in the publishing of this paper, it has been 

 necessary to revise it. It was first delivered to the society November 13th, 1892. 

 The revised copy was given to the Secretary of the Society November 13th, 1895. 



