24 Wisconsin Academy of Sciences, Arts, and Letters. 
stances observed at widely separated localities, the joints in ques¬ 
tion may be traced through the entire series of Lacustrian beds. ? 1 
Yellowstone National Park. —Quite recently Iddings 2 has 
shown that upon the Livingstone quadrangle, which is included 
in the area of the Yellowstone National Park, a net-work of 
faults has determined a fracture valley system in which the 
dominant directions are NE-SW, NW-SE, N-S, and E-W. 
More definitely the diagonal directions are given as N. 30° E., 
and N. 60° W. He says: 
“A study of the topographical map reveals the angular char¬ 
acter of much of the drainage system, and the prevalence of cer¬ 
tain parallel and sub-parallel lines which appear in various 
streams and occur in quite diverse portions of their channels. 
Along parallel lines different streams may be flowing in oppo¬ 
site directions: . . . The persistency of these lines becomes 
more striking when the geological structure of the region is taken 
into account and it is observed that certain drainage lines tra¬ 
verse rocks of such diverse nature as gneiss, schist, volcanic tuff, 
breccia, solid lava, limestone, sandstone, and shales. 
“The relation of some of these directions of drainage to 
known fracture planes will be pointed out. The dominant 
drainage lines in the southern tliree-fourths of the quadrangle 
trend about NE-SW, and NW-SE, more nearly N. 30° E. and 
W. 30° N., the angle between them being approximately 90 de¬ 
grees. There are other systems of almost rectangular lines 
somewhat differently oriented, namely, N-S and E-W.” 
Other Districts .—Only less important in a study of the orien¬ 
tation of fracture systems are other studies which will not be 
here specifically referred to except as they have been included in 
the following table. To facilitate the study of directions there 
are given in separate columns: 1st. Those bearings of fracture 
systems which approach the direction of the meridian; 2nd. 
Those which approach the direction of the equator; 3rd. Those 
which occupy intermediate positions within the quadrants NE 
and NW; 4th. Those which occupy intermediate positions in 
the quadrants NW and SE. 
