Hicks on Geyser He in Nebraska. 277 
must be accepted as a fact, that the disturbances of the Pittsburg 
coal measures, to a certain degree, must have affected the un- 
derlying Devonian formation and even the formation at the 
bottom of the latter, thus forming areas of more or less extent 
by clay veins etc. — Naturally, the greatest amount of gas should 
be found on the higher elevations (anticlinals) and of oil in the 
deeper portions of main and minor synclinals of the Devonian 
formation, or members of it; but as this theory is refuted by 
geologists of reputation, which certainly will prove to be correct, 
there remains especially the influence of disconnections and dis- 
locations of the oil and gas bearing strata by clay veins, etc., 
heretofore not mentioned at all, to explain the productivity of 
the oil and gas wells of Pennsylvania. 
GEYSERITE IN NEBRASKA. 
BY DR. LEWIS E. HICKS. 
In many counties of Nebraska occurs a fine, flour-like, white, 
or grey deposit, which is used as a polishing powder. It ex- 
cites much curiosity in localities where it is newly discovered 
and specimens of it are constantly being sent to the university 
for identification. I have just received a specimen from the 
northern part of the state with the inquiry whether it is emerv. 
Prof. J. E. Todd published in Science, Apr. 23rd, 1SS6, an 
account of its occurrence in Seward county, Nebraska, in strata 
of Quaternary age. He sent samj^les to Mr. J. S. Diller of the 
U. S. Geological Survey, who replied that it was volcanic dust. 
I have lately received a sample from Lindsberg, Kansas, and 
Mr. J. A. Udden, who sent it, has since informed me that,havino- 
forwarded samples to Washington, he was informed, by a member 
of the U. S. Geological Survey, "that it was volcanic dust. 
I wish now to recall the fact, once known to some portion at 
least of the geological world, that Prof. Samuel Aughey has 
given an extended description of this mineral in his "Physical 
Geography and Geology of Nebraska," published in 1880. His 
description is so full, minute and exact that it deserves to be re- 
produced entire. It is as follows: 
PoUshuig Poxvder — Inficsorial Earth — Geyser Flocula. One of the most 
remarkable of all the deposits of this Pliocene lake of the plains, is a 
