SLIDE 14 shows the Monitor pit as it appeared in 1979. The Monitor was
one of the properties acquired by Brush-Wellman from the Anaconda Company.
Even though the prospect is located beneath alluvium about two miles southwest
of Spor Mountain, the prospect pit exposes the beryllium tuff at shallow
depths. The tuff lies near the surface adjacent to concealed normal (mostly,
down-to-east) faults (see map by Lindsey, 1979).
SLIDE 15 shows two small beryllium prospects, the Hogsback (center of
view) and the Claybank (flat area in foreground) in The Dell. Both are in
erosional remnants of beryllium tuff in fault blocks. The view is to the
south in 1976, from the Claybank prospect; Eagle Rock Ridge is on the right
(west).
The Hogsback prospect consists of dozer cuts that completely encircle an erosional remnant of the porphyritic rhyolite member of the Spor Mountain Formation. The rhyolite overlies a somewhat larger area of fault-bounded beryllium tuff member.
A major basin-range normal fault passes southward along the east side of Eagle Rock Ridge, on the west side of the Claybank prospect, and along the west side of the Hogsback.