Usas Escarpment (-76°N, -130°W) is an expansive but discontinuous north-facing escarpment in Marie Byrd Land, Antarctica. It is about 200 nmi long, extending roughly west to east along the 76th parallel south from where the elevation of the snow surface descends toward the Ruppert Coast and Hobbs Coast. The position of the escarpment coincides with the north slopes of the Flood Range, Ames Range, McCuddin Mountains, and the eastern peaks of Mount Galla, Mount Aldaz and Benes Peak.

Location

The western end of the range is north of the Executive Committee Range. Mount Galla is towards the northeast end. Mount Aldaz and Benes Peak are further to the east.

Exploration and name

The escarpment was observed by members of the United States Antarctic Service (USAS), 1939–41, and in ensuing scientific reports was referred to as 76th Parallel Escarpment. The approved name is an acronym for the discovery expedition.

Features

Features of the eastern end of the escarpment, from west to east, are

Mount Galla

-75.93333°N, -125.86667°W. Snow-capped mountain 2,520 m high which rises above the Usas Escarpment, 31 nmi east of Mount Petras in the McCuddin Mountains. Mapped by the United States Geological Survey (USGS) from surveys and United States Navy air photos, 1959-65. Named by the United States Advisory Committee on Antarctic Names (US-ACAN) for Lieutenant Edward J. Galla, United States Navy, who was medical doctor and leader of support personnel at Byrd Station, 1959.

Mount Aldaz

-76.05°N, -124.41667°W. A projecting-type mountain 2,520 m high that barely protrudes from the ice-covered Usas Escarpment, 22 nmi east-southeast of Mount Galla. The mountain is mostly ice covered, but has notable rock outcropping along its northern spur. Surveyed by USGS on the Executive Committee Range Traverse of 1959. Named by US-ACAN for Luis Aldaz, Meteorologist and Scientific Leader at Byrd Station, 1960.

Benes Peak

-76.03333°N, -124.11667°W. A peak 2,450 m high that is almost entirely snow covered, situated along the Usas Escarpment, 4 nmi east of Mount Aldaz. Surveyed by USGS on the Executive Committee Range Traverse of 1959. Named by US-ACAN for Norman S. Benes, USARP meteorologist at Byrd Station, 1961.

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