Turnpike Bluff () is a conspicuous rock formation in

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

. First mapped in 1957 by the

Commonwealth Trans-Antarctic Expedition The Commonwealth Trans-Antarctic Expedition (CTAE) of 1955–1958 was a Commonwealth-sponsored expedition that successfully completed the first overland crossing of Antarctica, via the South Pole. It was the first expedition to reach the South ...

, and so named because it marks entry to a crevassed area of

Recovery Glacier The Recovery Glacier () is a glacier flowing west along the southern side of the Shackleton Range in Antarctica. First seen from the air and examined from the ground by the Commonwealth Trans-Antarctic Expedition in 1957, it was so named because ...

through which the Expedition's vehicles had difficulty in passing on their journey from Shackleton Base to the

South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...

in 1957, it lies five nautical miles (9 km) southwest of

Mount Homard Mount Homard () is a mountain high, near the head of Blaiklock Glacier, south of the Trey Peaks in the western part of the Shackleton Range The Shackleton Range is a mountain range in Antarctica. Rising at Holmes Summit to , it extends in an ...

, at the southwest extremity of the

Shackleton Range The Shackleton Range is a mountain range in Antarctica. Rising at Holmes Summit to , it extends in an east–west direction for about between the Slessor and Recovery glaciers. The range was named after Sir Ernest Shackleton, leader of the Br ...

Geology

The Turnpike Bluff Group is a

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

sequence of rocks exposed on the south flank of the Shackleton Range. The sequence includes basal

clastic Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks ...

s and

quartzite Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tect ...

, followed by

carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate g ...

-bearing clastics with Riphean age

stromatolite Stromatolites () or stromatoliths () are layered sedimentary formations (microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). The ...

colonies, and capped by over 1 km of

greywacke Greywacke or graywacke (German ''grauwacke'', signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lit ...

and quartzitic

arenite Arenite (Latin: ''arena'', "sand") is a sedimentary clastic rock with sand grain size between 0.0625 mm (0.00246 in) and 2 mm (0.08 in) and contain less than 15% matrix. The related adjective is ''arenaceous''. The equivalent ...

, alternating with

pelite A pelite (Greek: ''pelos'', "clay") or metapelite is a metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone. The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, ...

. The sequence is underlain

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

by an

Archean The Archean Eon ( , also spelled Archaean or Archæan) is the second of four geologic eons of Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth Earth ...

granitoid A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz ...

basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...

(1400 Ma).

Metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

occurred at 526 Ma.

References

Cliffs of Coats Land {{CoatsLand-geo-stub