The Cannonball Cliffs are cliffs at the south side of the terminus of Neptune Glacier

Neptune Glacier

Neptune Glacier is a glacier on the east coast of Alexander Island, 12 nautical miles long and 4 nautical miles wide, flowing east into George VI Sound to the south of Triton Point. First seen from the air by Lincoln Ellsworth on November 23, 1935, and roughly mapped from photos obtained on that...

 on the east side of Alexander Island

Alexander Island

Alexander Island or Alexander I Island or Alexander I Land or Alexander Land is the largest island of Antarctica, with an area of lying in the Bellingshausen Sea west of the base of the Antarctic Peninsula, from which it is separated by Marguerite Bay and George VI Sound. Alexander Island lies off...

. The feature consists of two east-west ridges about 500 metres (1,640.4 ft) high, joined by a narrow north-south ridge. The feature was mapped from trimetrogon air photography taken by the Ronne Antarctic Research Expedition

Ronne Antarctic Research Expedition

The Ronne Antarctic Research Expedition was an expedition from 1947-1948 which researched the area surrounding the head of the Weddell Sea in Antarctica.-Background:...

, 1947–48, and from survey by the Falkland Islands Dependencies Survey, 1948–50. The name was applied by the UK Antarctic Place-Names Committee

UK Antarctic Place-Names Committee

The UK Antarctic Place-Names Committee is a United Kingdom government committee, part of the Foreign and Commonwealth Office, responsible for recommending names of geographical locations within the British Antarctic Territory and the South Georgia and the South Sandwich Islands...

 for the sandstone in the area, which contains numerous spherical, brown concretions known as "cannon-ball" concretions.