Figure 2. Comparison of Lake Fryxell microbial mat morphology at shallow depths and the oxycline. Bubbles nucleate on microbial mats at shallow waters creating buoyant liftoff mat structures. (A) Liftoff mats below the ice-cover creating tented structures. (B) Liftoff mats at the deepest end of the liftoff zone with variable morphologies. (C) Prostrate mat in the oxycline overlying calcified liftoff structures.