Subtle folds are common on the lake surface, suggesting that the crust on the lake surface is thin and flexible. In addition, small “blisters” cover large portions of the lake surface. HVO geologists have seen these blisters form, and they appear to be small bubbles that rise and push up the thin crust, without breaking it. The field of view in this photo is roughly 50 meters (yards) wide. Photo taken Sunday, June 4, 2017 courtesy of USGS/HVO