EEPS Colloquium: Robert Anderson

 

Our department welcomes Professor Robert Anderson and Professor Suzanne Anderson from the University of Colorado - Boulder for two colloquia to be delivered Thursday September 3 at 11:30 and Friday September 4 at 12:00.

Thursday Professor Robert Anderson will present: 

The life cycle of rock glaciers

Rock glaciers are moving bodies of ice that are sufficiently covered in rocky debris to prevent any significant melt of their ice-rich cores. They are plentiful beneath tall headwalls in our mountains in the West, and constitute the largest manifestation of the modern cryosphere. Compared to their bright true glacier cousins, they are thin, stubby, slow and gnarly. Yet they cry out to be understood as we climb, mine, and photograph among them. I will describe research on three rock glaciers in Colorado’s mountains. We have constrained modern speeds using feature tracking, GNSS and RTK-GPS, and long-term speeds using 10Be in surface rocks. They are moving at speeds of typically 0.5 m/yr but up to 2 m/year in steep places. The landscape appears to have converted from true glacier to rock glacier domination after the Younger Dryas ~ 11 ka. The rock glaciers have been active over the Holocene and continue to advance down their valleys. Their health is governed by significant rockfall and snow avalanching to feed the “rooting zone” beneath the tall rock walls at the heads of the valleys. Numerical models that honor the birth of rock glaciers with sufficient caps of debris in the rooting zone, and subsequent motion of the ice by internal deformation can reproduce both modern and long-term displacement fields only when accommodating significant variation in the supply of avalanched snow over the Holocene.

Host: Roger Michaelides

EEPS Colloquia are made possible by the William C. Ferguson Fund