SHAW: SEDIMENTATION 513 



ethyl ester, the other two axes showing decreases of 15-20 per 

 cent in each case. Comparison of the diacetyl derivative with 

 morphine itself would show significant relations only if the an- 

 hydrous form of the latter were available; but on comparison 

 with anhydrous codeine, the monomethyl derivative, it is seen 

 that all three axes of the acetyl compound are about 10 per 

 cent longer than those of the methyl derivative, showing that 

 the acetyl groups produce their greatest increase in direction a, 

 but at the same time expand the structure somewhat in both of 

 the other directions. It is thus possible by this method to throw 

 some light on the positions of the chemical molecules in the 

 crystals of these substances. 



GEOLOGY. — Present tendencies in geology: Sedimentation} Eu- 

 gene WesIvEy Shaw, U. S. Geological Survey. 



Interest in sedimentation has both direct and indirect prac- 

 tical bearing. The economic value of this interest may lie for 

 the most part in the future, but should nevertheless be definite 

 and certain. We wish to know how geologic strata were formed. 

 The more we learn about processes and their results the more 

 we find there is to learn, and the more the field widens and 

 apparent complexity increases the more fascinating becomes the 

 subject. 



The main needs felt are (i) a better understanding of the 

 deposits of past ages; (2) a wider knowledge and better under- 

 standing of the processes now in operation and of their results, 

 as seen in the distribution of sediments, and the form of deposi- 

 tional surfaces— submarine, sublacustrine, subfluvial, subaerial, 

 and subglacial; (3) the ability to apply our knowledge to economic 

 problems the solution of which may rest on the nature of ancient 

 strata and the processes of their deposition, or on similar data 

 concerning present-day deposits. It can be demonstrated that 

 knowledge of sedimentation may reduce the costs of finding the 

 mineral treasure of the sedimentary basins, of harbor improve- 

 ment, of fish culture, etc. 



A knowledge of sedimentation involves a study of the processes 

 and immediate results of deposition; the source of sediment and 



^ Presented before the Geological Society of Washington, May 28, 1919. 



