NSS Convention 2026

Volcanic activity beneath glacial ice can create rare cave environments where focused heat from the underlying rock melts the overlying ice faster than the ice can "squeeze" the caves shut. Thermal springs and fumaroles are the major drivers of glaciovolcanic cave formation. The origin and shape of glaciovolcanic caves are intriguing; they originate from and are shaped by variations in climate and volcanic heat flux. In some cases, the interaction between volcanic heat and glacial ice more broadly can cause hazards for nearby communities. Thus, studies of glacier caves allow direct observations that can calibrate models of rates of glacial melt or movement, bedrock weathering and transport, and glacial outburst floods.

Interplay between volcanic heat and glacial ice on Mount Baker, Washington State, has created a dynamic cave environment in Sherman Crater present prior to volcanic unrest in 1975. A 2025 expedition leveraged specialized and international expertise to map more than 1.5 km of glaciovolcanic cave, conduct drone-based photogrammetry, collect thermal imaging scans, sample fumaroles and thermal springs for geochemistry, and catalogue the microbiology. Some in-cave streams are glacial melt and others with high conductivity are a mixture of glacial melt and volcanogenic waters.

Fumaroles exceed 90°C, are high in hydrogen sulfide, and have an isotopic profile consistent with a volcanic source. Geochemical syntheses, including standard geothermometers, reveal that waters in Sherman Crater are from a different source than fault driven groundwater flow at nearby Baker Hot Springs, which are different from non-thermal springs in surrounding carbonates, metasediments, and dunite.