How can melting buried ice create a lake?
A detached or stranded ice block surrounded by sediment can leave a depression when it melts. Such hollows are called kettles. Water-filled examples become kettle lakes, but a permanent lake does not always develop.
A hollow replacing the ice
Meltwater carrying sand and gravel can deposit material around stagnant ice at a glacier margin, partially or completely burying it. As melting proceeds, sediment above and beside the block settles downward. Hollow size depends on the former ice block and surrounding deposits. This differs from a lake basin directly excavated in bedrock by glacial erosion.
Water balance and later change
A hollow may hold water if it intersects groundwater or receives enough rainfall and runoff. Strong seepage through permeable ground can leave it dry or seasonally filled. Sediment and organic matter may gradually reduce its open-water area. Numerous small hollows on a plain can suggest former dead ice, but identification requires surrounding glacial deposits. Circular shape alone does not establish the formation process.