Correspondence. 437 
Proceedings of the U. S. National Museum (vol. viii, p. 99) a short paper, 
calling attention to the fact that certain deposits of fine white and gray 
dust located in Harlan and Furnas counties, Nebraska, and along the Re- 
publican river, extending into Kansas, and locally known as geyserite, 
were composed almost wholly of finely-comminuted pumice dust. Again, 
in the Am. Jour, of Sci. for September, 1886 (pp. 199-204), under the title 
of Notes on the composition of certain Pliocene sandstone from Montana and 
Idaho, the writer called attention to the fact that the fine-grained, light- 
colored and friable arenaceous rocks collected in 1871 by Dr. A. C. Peale, 
of the U. S. Geological Survey (F. V. Hayden in charge), were of a similar 
nature. In this latter paper particular care was taken to bring together in 
such form as to be available a number of references to the occurrence of 
these beds, not oply in Montana and Idaho, but also Nebraska, Kansas, 
eastern Colorado and Dakota. Both papers were accompanied by figures, 
showing the appearance of the dust as seen under the microscope, and the 
second also gave results of three chemical analyses on the Montana and 
Idaho samples. 
Since these papers were written, the writer has had an opportunity of 
personally insp-rcting the beds in Montana and Nebraska, and has not the 
slightest hesitancy in re-atfirming his opinion that the deposits are of vol- 
canic origin, i. «., are made up of volcanic dust (pumiceous) and sand, and 
owe their present purity and evenly stratified condition to the assorting 
agencies of water and atmospheric currents . 
To this same conclusion Dr. Hicks, aided by the U. S . geological survey, 
seems now to be coming gradually. That Prof. Aup;hey should, at the 
time he wrote, have failed to fully understand the natuie of the scales, is 
not at all strange. At the present time it is, however, difficult to under- 
stand how any one familiar with the nature of chemical precipitates, or 
ejected volcanic materials, can for a moment hesitate regarding the true 
nature of the beds in question. Geokge P. Merkii.l. 
U. S. Nat. Mas. Washington, July 30, 1888. 
Note on Mr. MerrilVs Letter. The "literature of the subject " is not lim- 
ited to the contributions of Mr. Jlerrill, as one might infer from the above 
letter from him. Interesting and important as his two papers are, we must 
credit another writer with the first correct account of the deposit in ques- 
tion. Dr. M. E. Wadsworth described specimens collected by Mr. Sam- 
uel Goiman between the White and Niobrara rivers (Lithological Studies, 
November, 1884, p. 17). It is " diflicult to understand " why Mr. Merrill 
" ignores" that account, which has priority over his own 
For my part, instead of ignoring the literature of the subject, I have 
given tresh currency to a very unique portion of it. Prof. Aughey's ex- 
planation of this fiour-like earth is the earliest of all. Though erroneous, 
as I intimated in the May number of the Geologist that it might be, his 
vision of Nebraska in tertiary times as "a great geyser region, far exceed- 
ing in tha number and magnitude of its geysers the Yellowstone region 
and Iceland at the present day," is too vivid and picturesque to be allowed 
to fade into oblivion. I am indebted to Mr. J. S. Diller for calling my at- 
tention to Wadsworth's paper, as well as for specimens communicated and 
many other courtesies. L. E. Hicks. 
