OHKMICAL AND ORGANIC DEPOSITS 739 



of marine sediments, and has already produced results of great importance 

 to the stratigraplier. 



It would go heyond the scope of this paper to mention all who have con- 

 tributed to the advancement of our knowledge of marine sediments, but 

 a few additional ones may be listed. Thus among contemporary English 

 writers we should mention Cornish, Wheeler, Blake, and Joly; among the 

 the French, Collet and Cayeux; among the Germans, Philippi, Schott, 

 and Supan, and among the Eussians, Js". Andrussow. The Americaii 

 workers in this field we all know, and some of them are to follow me in 

 this symposium. 



Chemical Deposits 



The study of modern chemical deposits has enlisted the attention of 

 many workers, both in this country and abroad. It would not be easy to 

 give an adequate analysis of the works of importance to the lithogenesist 

 in the short time allotted, but a few of the more prominent workers may 

 be noted. Perhaps we all agree that the studies of Usiglio, in 1849, on 

 the precipitation of salts from evaporating sea-water laid the basis for 

 most of our subsequent work on marine salts, and that the publications 

 of Ochsenius on rock-salt deposits and the mother liquor, in 1877, 1878, 

 and 1888, are of fundamental significance. The more recent, detailed 

 investigations of Van't Hoff and his associates, v^hich belong to the con- 

 tributions of the present century, are too well known to need further com- 

 ment. Many names might be cited of those who have added to our knowl- 

 edge of modern chemical sediments, both in the sea and on the continent, 

 but reference can be made only to a few. From among the many Ger- 

 mans who have attacked problems in this field we may note E. Erdmann, 

 Hochstatter, Lachmann, Linck, and Philippi. English contributors in- 

 clude Eobert Irvine and his associates on the work of the Challe7iger ex- 

 pedition ; the French workers, Paul Eeynard and others, and the Ameri- 

 cans, F. W. Clarke, I. C. Eussell, J. C. Branner, T. Sterry Hunt, E. W. 

 Skeats, and many others. 



Oeganio Deposits 



Eecent organic deposits, both on sea and land, have been treated per- 

 haps most extensively by Americans, though Englishmen, Germans, and 

 to some extent French investigators have furnished important contribu- 

 tions. The coral-reef studies of Darwin, Dana, and Davis, and those of 

 Agassiz, Murray, and Vaughan, are all well known. The Funafuti re- 



