Thomas Glacier is a roughly Z-shaped 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...

 which drains the southeast slopes of Vinson Massif

Vinson Massif

Vinson Massif is the highest mountain of Antarctica, lying in the Sentinel Range of the Ellsworth Mountains, which stand above the Ronne Ice Shelf near the base of the Antarctic Peninsula. The massif is located about from the South Pole and is about long and wide. At the highest point is Mount...

 and flows for 17 nautical miles (31 km) through the south part of the Sentinel Range

Sentinel Range

The Sentinel Range is a major mountain range situated northward of Minnesota Glacier and forming the northern half of the Ellsworth Mountains in Antarctica. The range trends NNW-SSE for about and is 24 to 48 km wide...

, Ellsworth Mountains

Ellsworth Mountains

The Ellsworth Mountains are the highest mountain ranges in Antarctica, forming a long and wide chain of mountains in a north to south configuration on the western margin of the Ronne Ice Shelf. They are bisected by Minnesota Glacier to form the northern Sentinel Range and the southern Heritage...

, leaving the range south of Johnson Spur

Johnson Spur

Johnson Spur is a rocky spur located 5.67 miles south-southeast of Taylor Spur and 8.65 miles north-northwest of Long Peak, forming the southeast extremity of Doyran Heights, Sentinel Range in Ellsworth Mountains, Antarctica. Overlooking Rutford Ice Stream to the east and Obelya Glacier to the...

. Discovered by U.S. Navy Squadron VX-6

VX-6

Air Development Squadron Six was a United States Navy Air Development Squadron based at McMurdo Station, Antarctica...

 on photographic flights of December 14–15, 1959, and mapped by United States Geological Survey

United States Geological Survey

The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

 (USGS) from the photos. Named by Advisory Committee on Antarctic Names

Advisory Committee on Antarctic Names

The Advisory Committee on Antarctic Names is an advisory committee of the United States Board on Geographic Names responsible for recommending names for features in Antarctica...

 (US-ACAN) for R. Admiral Charles W. Thomas, USCG, veteran of Antarctic expeditions in the 1950s.