Mt. Thielsen hosted the southernmost glacier in Oregon recognized on U.S.G.S. maps:
At left is the U.S.G.S. map with the glacier denoted and then a satellite image from September 2021.
Lathrop Glacier is gone as of 2020. Based on observations, it still existed as a flowing ice mass with crevasses in 2013.
With its disappearance, the southernmost glacier in Oregon is now Crook Glacier on Broken Top.