The Sinks, on the Little River,
TN., can be found along Laural Creek rd. Keep a sharp eye out and
follow the map, because it is easy to miss the very small parking lot
and no road signs mark the location,
(See location map for reference).
The geology of this sight is
interesting for two reasons, the erosional aspects and overturned
bedding. The deep pocket (~ 25ft deep +/-), called The Sinks, was
carved out of the weather resistant Thunderhead Formation sandstone.
These rocks have been eroded by millions of years of intense mechanical
weathering, from the cascading Little River. A great video of this
type of erosion can be seen on the Group C, Toxaway Gneiss page.
A member of the Ocoee Supergroup, the
Thunderhead Formation was emplaced as a part of the Greenbrier
thrust sheet. Only a thin sheet of Metcalf phyllite
separates the Thunderhead sandstone from surrounding beds of
identical lithology. Normal bedding at The Sinks was
overturned as the Thunderhead was thrust faulted on top of the Roaring
Forks Formation. This is easy to see at outcrop by the inverted
position of normal sedimentation ( Figure 3).
Deformational studies have shown
significant gliding within lattices structures of quartz, and breaking
in feldspar grains. Calcite and quartz veining has partially
recrystallized surrounding grain boundaries, (see Figure 4).
Metamorphism in this area was concurrent with regional orogenic
activity.
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Figure 2. Ripple marks. Represented by reddish layer below ruler
for scale.
Cross bedding is also present, but hard to see
(dark grey lamination
above ruler).
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