Lathrop Glacier

Lathrop Glacier, 1965 (A. Post)
Lathrop Glacier was "discovered" in 1966 when Dr. Theodore Lathrop peered from the summit down the north face of Mt. Thielsen and thought the two small snow and ice bodies he saw might be an active glacier.  Lathrop was an Oregon City physician, active hiker and climber and a member of the Mazamas, a Portland-based hiking club.  He was an expert on hypothermia, authoring a book, "Hypothermia - Killer of the Unprepared". The glacier was named for him in 1980.  Starting in 1968, Dr. Lathrop's nephew, Ralph Nafziger, and others began monitoring Lathrop Glacier's east and west lobes with photographs (taken during the late summer, usually in early to mid-September) after repeated attempts at placing stakes in the glacier surface failed. This small website displays a number of the photographs Nafziger and others have taken over the years. Additionally, see below for a summary of Lathrop Glacier written by Ralph Nafziger.

1968 - Looking upslope at the East Lobe

1970 - Large area of East Lobe has calved leaving 2 chunks of ice clinging to the mountain

1976 - note that the ice has reformed


1980 - Looking upslope at the East Lobe

Lathrop Glacier (East and West lobes). August 29, 2007
John Scurlock
The graph on right displays the area change of Lathrop Glacier since Ralph Nafziger began measurements in 1970. The large fluctuations in area result from periodic years of excessive snow accumulation and from the glacier periodically calving large chunks of ice. The gully in which the glacier resides traps lots of snow and probably because of the steep slope, when the ice becomes too thing, it calves under its own weight.


Nafziger, R.H. 2006. Lathrop Glacier - Oregon's Southernmost. Summary article of work done.



Anonymous, 1981, Oregon's southernmost glacier named for hypothermia expert, Oregon Geology, 43(2),20.

Lafrenz, M. D. 2001. The Neoglacial history of Mt. Thielsen, Southern Oregon Cascades. M.S. Thesis, Portland State University, Portland, OR, 80 p.

Lathrop, T.G., 1968, Return of the Ice Age?. Mazama, 50(13),34-36.<

Nafziger, R.H., 1971, Oregon's southernmost glacier: a Three-year

report. Mazama, 53(13), 30-33.

Nafziger, R.H., 1974. The geology of Mt. Thielsen: from Pliocene to present. The Geological Newsletter, 40,(11), 73-75.

Nafziger, R. H. 1976. Mt. Thielsen’s glacierettes: a five-year update. Mazama, 58(13), 17-20.

Nafziger, R. H. 1981. Lathrop Glacier revisited: 1976-1981. Mazama, 69(13), 50-51.

Nafziger, R. H. 1992. Update on Lathrop Glacier from 1988 to 1992. Mazama, 74(13), 106-107.

Created by Keith Jackson: 06.06.05
Last modified: 12.23.09