12 



The conditions of grov/tla, and the environiaental factors con- 

 trolling the deposition and the burial in the sea of the remains of 

 algae that :nake up a large part of the long buried carbonaceous sedi- 

 ments that now form the Icerosene shales, algal coals, and oil shales, 

 are still an open question. The fact that these algal deposits grade 

 into the ordinary black shales, cf marine origin, lends special 

 interest to the origin of the latter which has re'-.ei-r©d -many inter- 

 pretations. Is their blackness due to vegetable or to arilma.l ri^.-ri-'ra- 

 tives, or if to both, in what proportion? And by what ohenical alter- 

 ations have these shales been derived from the ordinary black marine 

 muds? 



The general problem of modern marine sediments as possible future 

 sources of oil, and of the oil distilla.ble therefrom, is now being 

 attached experimentally with the financial support of the American 

 Petroleum Institute, 



Another pressing problem is that of the amount of p/ater that is 

 contained in the modern sediments of different sorts, and of the 

 chemical composition of this water, which we have some reason to 

 believe may differ widely from ordinary sea water. No satisfactory 

 method of sanipling it has yet been devised. To estimate the rapidity 

 with which lime sediments are dissolved relative to their rate of 

 deposition, a knowledge of the degree of alkalinity of this entrapped 

 water and of that lying directly upon the sea bottom, is especially 

 desired. 



Interpreting "sedimentation" broadly, we may here mention the 

 assistance that a detailed charting of the regional and depth distri- 

 bution of the more monotonous communities of animals and plants of 

 skeletonr-building types, no-^' living on the sea bottom (e.g., coral or 

 Halimeda reefs, mussel or other shell beds, forests of deep sea 

 crinoids) would give to the geologist in his attempts to interpret 

 the age relationships of atrata that contain, in close association, 

 fossil communities that differ equally widely in character. 



The preceding remarks on marine sedimentation center around the 

 horizontal distribution of the various sediments. We must equally 

 emphasize the necessity of examining their vertical distribution, 

 e,g., of penetrating below the superficial layer, and of probing the 

 underlying mass. Here, however, as in so many submarine problems, 

 we face a practical obstacle. With deposition proceeding almost 

 everywhere in the sea (except right along the coastline, and in 

 certain restricted localities where currents scour the bottom) there 

 is no opportunity for a direct examination of geologic sections, 

 because no transversely dissected sedimentary layers are left exposed 

 there, or are accessible for examination if exposed, Further.nore, 

 while it is easy enough tc gather mud in any desired amount from 

 the uppermost stratum, and in any depth cf water, no method has yet 

 been devised for obtaining vertical cores of the bottom, more the.n 

 about 3-4 meters long, nor have any yet been obtained in the open 

 ocean more than a meter long. Picture how far geology would have 

 progressed on land, had there been no way of studying anything but 

 the top soill 



