The Hotlum 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...

 situated on the northeast flank of Mount Shasta

Mount Shasta

Mount Shasta is located at the southern end of the Cascade Range in Siskiyou County, California and at is the second highest peak in the Cascades and the fifth highest in California...

, in the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. It is the largest and most voluminous glacier in California, although not as thick or long as the nearby Whitney Glacier

Whitney Glacier

The Whitney Glacier is a glacier situated on Mount Shasta, in the U.S. state of California. The Whitney Glacier is the longest glacier and the only valley glacier in California. In area and volume, it ranks second in the state behind the nearby Hotlum Glacier. In 1986, the glacier was measured to...

. The Hotlum Glacier flows from a large cirque

Cirque (landform)

thumb|250 px|Two cirques with semi-permanent snowpatches in [[Abisko National Park]], [[Sweden]].A cirque or corrie is an amphitheatre-like valley head, formed at the head of a valley glacier by erosion...

 on the northeast side of Mount Shasta's main summit below the Hotlum Headwall at roughly 13,600 ft (4,150 m). It flows northeastward down the steep slope, forming three lobes which terminate near 10,400 ft (3,170 m).

In 2002, scientists made the first detailed survey of Mount Shasta's glaciers in 50 years. They found that seven of the glaciers have grown over the period 1951-2002, with the Hotlum and Wintun Glacier

Wintun Glacier

The Wintun Glacier is a glacier situated on the eastern flank of Mount Shasta, in the U.S. state of California. It is both the third largest and third most voluminous glacier in California after the neighboring Hotlum Glacier and the Whitney Glacier...

s nearly doubling, the Bolam Glacier

Bolam Glacier

The Bolam Glacier is a glacier situated on the northern flank of Mount Shasta, in the U.S. state of California. It is the second longest glacier in California behind the nearby Whitney Glacier, and the fourth largest and most voluminous after the neighboring Hotlum Glacier, Whitney Glacier, and...

increasing by half, and the Whitney and Konwakiton Glaciers growing by a third.