166 
GEOLOGY: E. BLACKW ELDER 
bacteriological experiments of Drew and others on the precipitation of calcium 
carbonate from sea-water and the formation of oolites. On the whole there 
has been much too little of this sort of work in the last few decades, perhaps 
because sedimentary studies have been left largely to the stratigrapher who 
is rarely, by force of habit, a laboratory experimenter. We shall need in this 
work the cooperative aid of expert chemists, bacteriologists, and others not 
ordinarily interested in geologic matters. The whole subject of diagenesis, 
or simultaneous alteration of sediments, is doubtless in the province of the 
bio-chemists and colloid chemists, if only we could induce them to assume the 
task. 
It might seem, at first thought, superfluous for me to recommend the thorough 
combing of the geological literature for material on the nature and origin of the 
sediments. But it is a fact, by no means sufficiently appreciated by most of 
us, that the amount of buried treasure of this kind is really enormous. A 
few years ago, while engaged in the study of phosphorite deposits, I was 
astonished to find that the papers published in France and England during the 
seventies contained a much clearer and more comprehensive interpretation of 
phosphatic deposits than could be found in any American text-book or ref- 
erence work published since 1900. In fact, it was perfectly evident that 
most even of the more valuable of these foreign papers had never been seen by 
the authors of the compendia mentioned, nor even by Americans who had 
published important papers on the phosphatic rocks. I believe it is a fact 
that one of the greatest services that can be rendered, just now, to the advance- 
ment of our knowledge of sediments and sedimentary rocks would be the 
thorough investigation, digestion, and summarizing of what is already in 
print on the various types of sediments. It would vastly increase our effective 
working knowledge and might conceivably double it, for it must be clear that 
a fact or a theory which is lost is as useless as one that has never been found out. 
Chemical analyses give much valuable information regarding sedimentary 
deposits. Not infrequently the general conditions of origin as well as the 
nature of the rock, can be inferred at once from the analysis. We have far 
too few of them, and it is one of the minor discouraging conditions of the 
study that even those we have are in many instances rendered useless by the 
omission of essential facts. 
Furthermore, a great many analyses are published with only the most 
meager information regarding the source of the material. It is obviously of 
very little value to the sedimentationist to know that a certain analysis per- 
tains to a Cretaceous shale from Mt. Diablo, California, because the mountain 
contains several distinct types of shales of Cretaceous age. In that case even 
the brief statement that it was a gray sandy shale with abundant fragmentary 
mollusks and echinoderms would greatly enhance the value of the analysis. 
The same benefit might be conferred by noting that the specimen came from a 
particular bed in a carefully described section already published. It is for this 
reason that the great number of analyses in Clarke's Data of Geochemistry, 
