Why some Alaskan rock glaciers race downhill while their neighbors barely move
Two massive rock glaciers are creeping down mountain valleys in Alaska's Wrangell–St. Elias National Park. They sit only a few miles apart and formed under the same sky. One moves more than 5 feet (1.5 meters) a year. The other moves at less than half that pace.
Two massive rock glaciers in Alaska's Wrangell–St. Elias National Park differ greatly in speed despite being only a few miles apart and formed under the same conditions. SMU researchers found that the key factor is the aspect of the slope, specifically which way it faces. Utilizing five years of satellite radar data, they determined that snowmelt, late-summer rain, and solar radiation are the primary drivers of seasonal motion.
The radar revealed that Sourdough Peak, a south-facing hill, speeds up more than McCarthy Creek, a north-facing slope, due to increased sunlight warming the subsurface and enabling water to reach the sliding layer. This discovery could aid in monitoring thousands of similar rock glaciers worldwide, crucial for understanding water storage in mountain communities and permafrost health.
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