86 
DYNAMICAL GEOLOGY 
If homogeneous environmental and time conditions be premised, 
it is yet to be shown that these are sufficient to overcome the heter- 
ogenity of the physical properties of the rocks and to cause homo¬ 
geneous behavior through any considerable zone. It is not even 
certain that they may not fix and accentuate the heterogeneous 
properties of rocks. Certainly in the zone of observation there 
is comparatively slight evidence of their efficacy in causing more 
uniform deformation with depth. Leith. 
Discovery of Gilbert's Star} Wide interest was aroused several 
years ago when G. K. Gilbert announced that when he visited 
Arizona a short time before he examined a large crater-like de¬ 
pression, hollowed out below the level of the surrounding plain, 
and about which large numbers of metallic iron fragments had 
been found. Coon Butte the place was designated by the dwellers 
about. Regarding the origin of this wonderful hole in the ground 
the hypothesis was advanced that it was due to a huge meteor 
striking the earth. 
The features of this locality include three things of unusual 
character which require explanation: (1) the deep hole ringed 
all around with a ridge composed of non-volcanic materials; (2) 
the abundance of scattered meteoric iron; and (3) the association 
of the two phenomena. 
The features displayed are not nearly so unusual as Gilbert 
would have us believe. Meteoric irons are especially abundant 
in the dry scant soils of the desert. It is not probable that they 
are really any more numerous in this locality than they are in 
other equal areas of the earth’s surface, but simply that they are 
more easily found. The strong desert winds keep the soils re¬ 
moved and the rock-floor of the plains swept clean so that the 
heavy iron fragments are left behind exposed to plain view. 
So abundant are. the fragments that the Indians of the region 
make it a regular business to collect these irons to sell as curiosi¬ 
ties to tourists on the trans-continental railroad trains. As a mat¬ 
ter of fact meteoric irons are far more abundant a hundred miles 
from Coon Butte than they are around the depression. 
1 Under this title a paper from which the present note is abridged, was read before 
the Geological Society of America at the Ottawa Meeting. In publishing it in Volume 
xvii of the Bulletin the editor asked permission to change the title to “Volcanic 
Craters in the Southwest,” which was accordingly granted. »• 
