230 C. P. BERKEY PALEOGEOGRAPHY OF SAINT PETER TIME 



This data has been checked wherever possible by the writer's own ob- 

 servations,* which, together with his examinations f of material, form 

 the basis of the discussion. 



The work has been carried on in the Stratigraphic Laboratory at 

 Columbia University, and was undertaken at the suggestion of Professor 

 Grabau, in whose classes the researches have been discussed and to 

 whom the writer is indebted for many suggestions. 



The Saint Peter sandstone has often been described in admirable 

 detail. J To this feature the present writer has added little. To the 

 comparative side and the resulting interpretation as to conditions pre- 

 vailing during the time represented by this formation this discussion of 

 what is otherwise so well worn a subject is directed. If the conclusions 

 are well founded, then they explain the problem of origin also; and its 

 uniformity of grain, its purity of composition, its great extent, its appar- 

 ent conformity to adjacent beds are not inexplicable sedimentary puzzles. 



From the nature of the undertaking, it will be necessary to summarize 

 the essential points of the facts gathered from observers touching this 

 formation and later to compare and interpret local variations. 



Since finishing the manuscript of this article§ the writer's attention 

 has been called to a paper by A. Eutot, which contains a very suggestive 

 discussion of the principles involved in sedimentation, and includes the 

 same ideas and general treatment that are here applied to a particular 

 case. 



General Character and Distribution of the Sandstone 



The Saint Peter formation is a quartz sandstone, a silicarenyte. In 

 most descriptions the same characteristic are enumerated. It is coarse 

 and uniform grained, with almost no cementing material and little im- 



* These consist of field- observations for many years in the Upper Mississippi Valley 

 region. 



t Recent laboratory study of material obtained from localities distributed throughout 

 the areal extent of the formation. 



+ To attempt a complete acknowledgment of the sources of information on this sub- 

 ject is scarcely practicable. They are exceedingly numerous. The chief publications 

 relied on, however, are those of the Geological and Natural History Survey of Wisconsin, 

 the Geological and Natural History Survey of Minnesota, the Geological Survey of 

 Iowa, the Geological Survey of Missouri, the Geological Survey of Illinois, the Geolog- 

 ical Survey of Michigan, including descriptions and discussions by T. C. Chamberlin. 

 N. H. Winchell, W. H. Norton, C. R. Keyes, Samuel Calvin, James Hall, J. D. Whitney, 

 A. H. Worthen, James Shaw, F. L. Nason, and others. Among authors of important 

 special papers or reports are D. D. Owen, Joseph F. James, C. W. Hall, F. W. Sardeson. 

 Citations are made to many of these at appropriate points throughout the paper and 

 especially in those matters with which the present discussion is mainly concerned. 



$ A. Rutot : Les Phenonienes de la Sedimentation Marine. Bull. Musee Royal 

 d'Histoire Naturelle de Belgique, T. ii. 41-83, 1883. 



[| Journal of the Cincinnati Society of Natural History, July, 1894, p. 120. The St 

 Peter's Sandstone, by Joseph F. James. 



