Large glaciers like Saskatchewan Glacier create depressions in the bedrock due to an added load. As the galcier retreats and melts, these depressions are filled with ice, glacial meltwater, and sediment, forming glacial lakes such as the one in image A. Images B and C depicts the the lake floor beginning to form mudcracks and is composed of fine sediment and sand. Mudcracks are sedimentary structures that form when mud undergoes drying and contracting due to interchanging wet and dry environments. Long dry periods cause fine clay materials to lose their moisture forming cracks, while wet seasons allow for sediment transport to infill the cracks before the mud is remoisturized and swells.