4
273 stations and shows that the most radioactive zones lie
on the “fingers” that extend to the northeast. The highest
values reach 760 cps. Elevated values are also found on the
wider, southeastern portion of the mesa. As radioactivity
decreased in lower elevation portions of the mesa, it is
likely that the mineralized horizon has been locally eroded.
The survey of Flat Top Hill West was comprised of 75 sta-
tions. The most radioactive zones are generally confined to
the southwestern edge of the ridge, with the highest value
reaching 420 cps. This deposit appears to be less mineral-
ized or more eroded (or both) than Flat Top Hill East. No
other apparent northwest trending mesas or ridges appear
in the vicinity of Flat Top Hill, so it is unlikely that these
deposits continue elsewhere.
The Farr Ranch Deposit (Figure 4) lies on a 1.2 kilo-
meter long, northwest trending, southwest sloping mesa
with a steep northeast face. 71 stations were surveyed over
this deposit. The zones of highest radioactivity were located
on the northwest-central portion of the mesa and reached
1200 cps. Similar to Flat Top Hill, lower elevations on the
mesa corresponded with lower radioactivity, suggesting ero-
sion of the mineralized sandstone.
The Hogback Deposit is so named because it lies along
the Hogback near Shiprock. The radiometric survey over
the deposit (Figure 5) consists of 82 stations on a southeast
sloping hill on the west side of Coal Mine Creek. Unlike
the other surveyed deposits, the Hogback Deposit appears
to exhibit less topographic control than the deposits found
on relatively prominent mesas or ridges. The radiometric
Figure 3. Ground radiometric survey of the Flat Top Hill
East and West Deposits. Flat Top Hill East shows the most
mineralized zones along the “fingers” extending towards
the northeast. Flat Top Hill West is less mineralized, with its
most elevated values lying on the southeast edge of the ridge
Figure 4. Ground radiometric survey of the Farr Ranch
Deposit showing a northwest trending mesa with zones of
highest radioactivity located towards the northwest end of
the mesa
273 stations and shows that the most radioactive zones lie
on the “fingers” that extend to the northeast. The highest
values reach 760 cps. Elevated values are also found on the
wider, southeastern portion of the mesa. As radioactivity
decreased in lower elevation portions of the mesa, it is
likely that the mineralized horizon has been locally eroded.
The survey of Flat Top Hill West was comprised of 75 sta-
tions. The most radioactive zones are generally confined to
the southwestern edge of the ridge, with the highest value
reaching 420 cps. This deposit appears to be less mineral-
ized or more eroded (or both) than Flat Top Hill East. No
other apparent northwest trending mesas or ridges appear
in the vicinity of Flat Top Hill, so it is unlikely that these
deposits continue elsewhere.
The Farr Ranch Deposit (Figure 4) lies on a 1.2 kilo-
meter long, northwest trending, southwest sloping mesa
with a steep northeast face. 71 stations were surveyed over
this deposit. The zones of highest radioactivity were located
on the northwest-central portion of the mesa and reached
1200 cps. Similar to Flat Top Hill, lower elevations on the
mesa corresponded with lower radioactivity, suggesting ero-
sion of the mineralized sandstone.
The Hogback Deposit is so named because it lies along
the Hogback near Shiprock. The radiometric survey over
the deposit (Figure 5) consists of 82 stations on a southeast
sloping hill on the west side of Coal Mine Creek. Unlike
the other surveyed deposits, the Hogback Deposit appears
to exhibit less topographic control than the deposits found
on relatively prominent mesas or ridges. The radiometric
Figure 3. Ground radiometric survey of the Flat Top Hill
East and West Deposits. Flat Top Hill East shows the most
mineralized zones along the “fingers” extending towards
the northeast. Flat Top Hill West is less mineralized, with its
most elevated values lying on the southeast edge of the ridge
Figure 4. Ground radiometric survey of the Farr Ranch
Deposit showing a northwest trending mesa with zones of
highest radioactivity located towards the northwest end of
the mesa