GENERAL32961

• Permit No: M1999002
• IBM Index Class Name: General Documents
• Doc Date: 8/18/1998
• Doc Name: COMMERCIAL MINE PLAN SUBMITTED TO BLM SECTION 7
• Media Type: D
• Archive: No

• (Formation). A generalized south-north cross section of the Piceance Creek Basin,
illustrating the Tertiary sequence of rocks, is shown in Figure 7-2. The stratigraphic
sequence of interest to the American Soda project are the Tertiary-age rocks of the
Parachute Creek Member of the Green River Formation (Figure 7-3).
Quaternary Unconsolidated Sediments
Unconsolidated Quaternary sediments consist of Holocene alluvium and
Pleistocene terrace deposits. The Quaternary alluvium is found in the river valleys
and along dry washes. Alluvial floodplain deposits are mostly gray, brown and buff-
colored silt, sand, and gravel. Alluvial fan deposits consist of angular sandstone and
marlstone boulders and pebbles mixed with silts and sands derived from nearby
hilly terrain. The alluvium may reach up to 140 feet thick in the Piceance Creek
Basin. However, near the Piceance Site, the alluvium is less than 50 feet thick.
Pleistocene terrace deposits of glacial origin occur as accumulations of remnant
older stream deposits on terraces high above the present-day valley floors. These
deposits contain smoothly rounded pebbles and boulders of chert, limestone,
quartzite, arkose, and sandstone derived from Paleozoic and Mesozoic rocks east of
the Piceance Creek Basin. The thickness of these deposits varies from 0 to 25 feet
(Duncan 1976).
• Uinta Formation
The Uinta Formation outcrops throughout most of the Piceance Creek Basin and is
situated below the unconsolidated Quaternary sediments. The Uinta Formation
consists of sandstones with interlayered sequences of siltstones and marly silts tones.
Marlstone is more abundant in the lower portion of the formation. In the central
part of the Piceance Creek Basin, the Uinta Formation generally exceeds 1,000 feet in
thickness; it is 674 feet thick at monitoring well 20-1Z (USGS Cl), an existing
discovery hole drilled at the Piceance Site in 1965. The sandstones are massive,
usually devoid of visible stratification, and generally fine- to medium-grained.
Occasional coarse-grained and pebbly sandstone layers 1 to 2 feet thick are also
present. The interstratified finer-grained rocks (i.e., siltstone, sandy siltstone, and
marly siltstone) tend to be tabular, and stratification is not very distinct. Above the
influence of groundwater, detrital rocks are typically brown, tan, or buff-colored,
while below the influence of groundwater they are usually gray. The mineralogy of
the Uinta Formation includes both detrital and authigenic minerals. The detrital
grains include quartz, potassium feldspar, illite, and silica-rich volcanic rock
fragments. Authigenic cements consist of calcite and dolomite along with
considerable quantities of analcime. Marlstone and lean oil shale are composed
primarily of quartz, dolomite, calcite, and analcime (Cole 1975, Ochs and Cole 1981}.

Early reports written in the 1960s refer to core hole 20-1 as "Nielsen core hole ZO-1"; USCS
reports refer to it as "Cl."
American Soda. L.L.P.
Commercial Mine Plan
August ta, tv9a
7-4