Maryland Geological Survey 113 



because most of it deals with the deposits of the deeper ocean, little with 

 the deposits near and adjacent to the mouths of rivers. Probably no inves- 

 tigator of modern sediments has bad the geologic bearings of the study so 

 forward in his mind as Thoulet, and it is his publications therefore, limited 

 in extent though the work of one man must be, that are of most value 

 to the geologist. Foremost in his work in this connection stands the 

 recently published monograph, with colored maps, of the sediments of 

 the Gulf of Lyon ; * and the work of his pupil Sudry 2 on the Lagoon of 

 Thau in the same region is, as subsequently pointed out, probably of par- 

 ticular bearing on the Matawan. (See especially sample 8, below.) 



References to such studies as have been made of near-shore sediments 

 will be found in Andree's bibliography, but as far as I know the only syste- 

 matic and continuous investigation of this type, and the only one whose 

 results are expressed in the tangible form of a map is that by Thoulet of 

 the Gulf of Lyon. In fact it is, I believe, the need for studies of this 

 kind that inspired him to carry out the work. 



The Method of Analysis 



In all essentials it is Thoulet's 3 method of analysis that has been fol- 

 lowed in this investigation. 



In a general way three main types of procedure in the analysis of unin- 

 durated sediments, whether ancient or modern, may be recognized. The 

 first is the method of elutriation in which a separation, mainly of the clay 

 and finer parts from the sand, is made by subjecting the sample to a rising 

 current of water whose velocity is known and can be regulated. This 

 method cannot be used, however, to subdivide material finer than \ mm., 

 because finer particles settle too slowly to oppose any velocity of current 



1 Thoulet, J., Etude bathylithologique des cotes du Golfe du Lion. Annates 

 de l'lnst. Oceanograph., T. iv, Fasc. 6, Paris, 1912, 66 pp. Maps. 



2 Sudry, L., L'Etang de Thau. Ann. de l'lnst. Oceanograph., T. i, Fasc. 10, 

 Monaco, 1910, 208 pp. 



3 Thoulet, J., Precis d'analyse des fonds sous-marins actuels et anciens. Paris: 



Chapelot et Cie, 1907, 220 pp. Instructions pratiques pour l'etablissement 



d'une carte bathymetrique-lithologique sous-marine. Bull, de l'lnst. Ocean- 

 ograph., No. 169, Monaco, 1910, 29 pp. 



