Grotto Glacier is a glacier

Glacier

A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...

 on the east coast 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...

 which flows east to George VI Sound

George VI Sound

George VI Sound or Canal Jorge VI or Canal Presidente Sarmiento or Canal Seaver or King George VI Sound or King George the Sixth Sound is a major bay/fault depression, 300 miles long in the shape of the letter J, which skirts the east and south shores of Alexander Island, separating it from the...

 between Belemnite Point

Belemnite Point

Belemnite Point is the eastern extremity of a mainly ice-free, hook-shaped ridge, midway between Lamina Peak and Ablation Point and inland from George VI Sound on the east coast of Alexander Island, Antarctica. It was first photographed from the air on November 23, 1935, by Lincoln Ellsworth and...

 and Ablation Point

Ablation Point

Ablation Point , also known as Punta Ablación, is the east extremity of a hook-shaped rock ridge marking the north side of the entrance to Ablation Valley on the east coast of Alexander Island. First photographed from the air on November 23, 1935, by Lincoln Ellsworth and mapped from these photos...

. It is 25 nautical miles (46 km) long, 3 nautical miles (6 km) wide where it emerges from the coastal mountains, and 7 nautical miles (13 km) wide at its mouth. First photographed from the air on November 23, 1935, by Lincoln Ellsworth

Lincoln Ellsworth

Lincoln Ellsworth was an arctic explorer from the United States.-Birth:He was born on May 12, 1880 to James Ellsworth and Eva Frances Butler in Chicago, Illinois...

 and mapped from these photos by W.L.G. Joerg. Roughly surveyed in 1936 by the British Graham Land Expedition

British Graham Land Expedition

A British expedition to Graham Land led by John Lachlan Cope took place between 1920 and 1922. The British Graham Land Expedition was a geophysical and exploration expedition to Graham Land in Antarctica between 1934 to 1937. Under the leadership of John Riddoch Rymill, the expedition spent two...

 (BGLE) and resurveyed in 1949 by the Falkland Islands Dependencies Survey (FIDS). So named by FIDS because a sledge dog was rescued from a crystal-line crevasse

Crevasse

A crevasse is a deep crack in an ice sheet rhys glacier . Crevasses form as a result of the movement and resulting stress associated with the sheer stress generated when two semi-rigid pieces above a plastic substrate have different rates of movement...

in this glacier.