Art. IV.] Herrick, Geology of New Mexico. 89 
where lead, copper and silver are collected, while near the crest, 
in dykes of felsite penetrating the andesite, gold has accumu- 
lated in appreciable quantities. Andesite areas which are evi- 
evidently the offspring of Big Baldy give rise to the well-known 
properties now being developed in the south end of the range. 
These are immediately associated with the andesites at the foot 
of Timber Peak, a lofty mountain east of Big Baldy. 
On the west side of the range southward from Little Baldy, 
and extending to the west, north-west and south-west at a gen- 
tle inclination for many miles, is a very extensive system of 
acid flows which seem to have been derived from a fissure or 
system of fissures somewhatito the westward of the older ande- 
site axis. These flows are of trachyte, obsidian, trachyte tuff 
and rhyolite. The obsidian is often black and is not infre- 
quently found in brecciated fragments the later or rhyolite 
flows. Enormous erosion has operated to remove a great part 
of the flows and to carve the remainder into ribs and butte-like 
outlyers. The trachyte now seems originally to have extended 
northward and eastward to the very foot oi” the range, but this 
portion has been nearly entirely removed by subsequent eros- 
ion, leaving a series of low mountains or buttes at a distance of 
about a mile from the western foot of the range proper, while 
the valley in which are situated the towns of Kelly and Magda- 
lena, as well as the Graphic and Iron Mask smelters, intervenes. 
Two of these isolated hills are prominent and well known land- 
marks, Elephant butte being the southern and Mount Magda- 
lena the northern. These two are essentially similar in struc- 
ture and form part of the great overflow which can be traced far 
to the south-west. 
Mount Magdalena (Plate XII) owes its name to a remarka- 
ble patch of talus which is circumscribed by oak shrubs form- 
ing the perfect outline of a female head. This figure presents 
itself to the approaching traveler from the east and has been 
embalmed in the usual myths and legends. In spite of its ap- 
parently trivial nature, it seems to have remained practically 
unchanged for over 300 years, in fact, from the time of the ar- 
rival of the Spaniards, whose devout imaginations saw in its 
