The Geological Society of America. — Hovey. loi 
trend of the valley. To the observer it is very apparent that these 
vertically jointed planes are the cause of the vertical clififs. The en- 
tire canyon is believed to have been cut out by river erosion assisted 
by the jointing. Subsequently the valley, in common with the other 
canyons of the high Sierra, was filled with glacial ice and a large 
amount of talus may in this way have been removed. This glacier 
left a number of moraines at the west end of the valley which have 
served as barriers to the drainage and caused the formation of the 
valley floor. 
" The Origin of the Grahai/iife in Ritchie Co., IV. Fa. /by I. 
C. White, state geologist of West \'irginia. Grahamite is a black, 
coaly mineral, looking like anthracite which is very closely allied to 
the albertite of Nova Scotia. It consists essentially of 79 per cent, 
carbon, 6^ per cent, hydrogen and 14 per cent, oxygen. In Ritchie 
founty, it occurs in a vertical fissure nearly five feet wide, seven miles 
from the ridge known as the "oil-break," which is the top of an an- 
ticlinal fold. Years ago it was mined as a fuel, but never at a profit. 
Within about a year well-paying oil wells have been put down within 
a few hundred feet of the fissure. The theory of origin is that the 
fissure, which was caused by the forces producing the anticline, tapped 
the Pottsville conglomerate oil-sand, and that the oil flowed until 
nature plugged up the orifice with the oxidized oil, parafifine, tarry 
products, etc., form the consolidation of which the grahamite has re- 
sulted. 
" Structure of the lot a Gas Field, Allen Coti7ity, Kansa?,," 
by Edward Orton, Columbus, O., read in the absence of the 
author by I. C. White. Natural gas is more widely distributed, geo- 
logically and geographically, and exists in larger quantity than any 
one would have claimed 20 or even 10 years ago. Its productive 
horizons cover the entire Paleozoic column of the country. Cities 
supplied, at least partially, with natural gas for iweX and light are no 
longer uncommon. Two distinct divisions can be made of its ac- 
cumulations, viz.: That which is stored in impervious rocks as shales, 
most limestones, etc., and that which is found in porous rocks. These 
divisions may be provisionally styled Shale gas and Reservoir gas: 
each having characteristics of its own. Shale gas occurs in com- 
paratively small wells. Its wells lack uniformity of rock pressure. 
It does not occupy definite horizons; it exists independently of pe- 
troleum in many cases, has staying properties — does not depend on 
the structural arrangement of the strata that contain it. Reservoir 
gas is found in great wells; approaches uniformity of rock pressure 
in each subdivision of territory, occupies definite horizons, is ac- 
companied by oil, its wells generally come to a sudden end — is en- 
tirely controlled by the structure of the rocks in which it is accumu- 
lated. Two structural phases of rocks are specially important in this 
connection, the anticline and the terrace. The time has come for the 
acknowledgement of structure in reservoir gas fields even in advance 
of measurements. The lola gas field is one of great promise. Its 
