100 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



posits are found in many places in semicircles from 4 feet high to 10 

 feet, in different-colored layers and quality, of an inch in thickness, rest- 

 ing on fine sand or sandy calcareous marls. The largest deposit I have 

 seen I found about 100 steps in the circle, with dips of 3 degrees. On 

 top is generally found calcareous limestone (?) 6 to 12 inches thick, 

 then comes coarse gravel and sometimes loess only. * * * These 

 deposits I would judge to be about 100 feet higher than the level of the 

 river. The white deposit in Harlan County, I find since I first discov- 

 ered it, extends a good way under the hill. A farmer dug a well 2J 

 miles east and soutli and found the same deposit 4 feet thick, 30 feet 

 from the surface." 



A glance at the samples was sufiBcient to convince the writer that 

 they were not the result of geyser action, but were probably of volcanic 

 origin. One was of almost chalkj^ whiteness, very finely pulverized, and 

 of a sharp, gritty feeling when rubbed between the fingers. The sec- 

 ond was gray in color, slightlj^ coarser, and had, even to the naked eye, 

 a flaky appearance. Submitted to microscopic examination both sam- 

 ples were found to consist almost entirely of the minute particles of 

 amorphous glass, such as originate from the fine pulverization of a glassy 

 pumice, with only occasionally a fragment of a greenish, mineral that 

 was apparently hornblende. 



The figures given below show the more common forms of these flakes. 

 The actual size of the larger one is some 0.3™™ in diameter. 



d o 



On writing a second time to Mr. Zahn that gentleman was kind 

 enough to forward samples of the sandstone from the top of the depos- 

 its and also another sample such as is found "in some places on top 

 and sometimes below the deposit, or in close proximity." Both were 

 very friable, crumbling readily between the thumb and fingers. Sub- 

 mitted to the microscope they proved to be comi^osed entirely of small 

 cleavage plates of a triclinic feldspar, particles of a green hornblende, 

 grains of iron ore, and numerous other grains, evidently feldspathic, 

 but otherwise undeterminable. No quartz was observed. All were 

 distinctly rounded, having evidently been waterworn. From these 

 facts the present writer does not hesitate to pronounce all the deposits 

 as of volcanic origin, ie., volcanic dust and sand, owing their jiresent 

 evenly stratified condition to the assorting agencies of water and at- 

 mospheric currents. 



As, so far as the writer is aware, no deposits of this nature have 

 heretofore been recognized east of the Rocky Mountain region, this in- 

 stance seems worthy of the space here devoted to it. 



National Museum, April 2, 1885. 



