PAPERS ON GEOLOGY AND GEOGRAPHY 209 



THE GENESIS OF THE SEDIMENTARY ROCKS— 

 AN UNDEVELOPED FIELD IN GEOLOGY 



ABSTRACT 



By Francis M. Van Tuyl, Colorado School of Mines 



The value of more careful examination of the sedimentary 

 rocks both in the held and in the laboratory is emphasized. 

 Critical study of these will undoubtedly throw a flood of light 

 upon many problems connected with their origin, and will 

 furnish additional data regarding the paleogeography of past 

 geologic ages. 



(Complete paper published in Proceedings of Iowa Acad- 

 emy of Science, 1915, under the following title: "The Litho- 

 genesis of Sediments.") 



THE CHLORITIC MATERIAL IN THE ORES OF 

 SOUTHEASTERN MISSOURI 



ABSTRACT 



C. S. Ross, Geological Survey, Washington, R. C. 



In the Bonneterre formation of southeastern Missouri a 

 mineral occurs, associated with the lead ores, that has long 

 been referred to as "chloritic material." Spurr has casually 

 referred to it as glauconite. 



A microscopic study of this mineral shows that its optical 

 constants are very different from those of chlorite. An ap- 

 proximate test for potassium indicates the presence of about 

 9 per cent of KoO. 



From the foregoing it is evident that the mineral cannot be 

 chlorite, but must be glauconite, since all its optical proper- 

 ties agree with those of the latter mineral. 



A more extended account of the Missouri glauconite was 

 published in "Economic Geologv," Vol. XI, No. 3, April-Mav, 

 1916. 



