Complex sentence: The north end of the feature was photographed by Lincoln Ellsworth on his trans-Antarctic flight of November 23,1935, and the bluffs were mapped by the United States Geological Survey in 1961 from air photos obtained by U.S. Navy Squadron VX-6 in 1959.
Split into simpler sentences: The north end of the feature was photographed by Lincoln Ellsworth on his trans-Antarctic flight of November 23,1935. The bluffs were mapped by United States Geological Survey (USGS) in 1961 from air photos obtained by U.S. Navy Squadron VX-6 in 1959.