There is another theory that I see as absent here, at least as it applies to the "crater" locations on the Croatan National Forest in North Carolina. The lakes that you have pointed out as appearing as "craters" are currently in the center of a giant ecosystem consisting of raised bogs / peatlands known locally as Pocosin (AKA "Swamp on a Hill"). The theory as I understand it is that these raised swamps were created when a drainage was blocked by debris and water began to pool behind it and over a long period of time vegetation and organic matter built up creating raised swamps and soils that are organic in nature. The Pocosin vegetation is composed of lots of highly flamible plant material with lots of natural oils creating a sort of fire adapted ecosystm. In normal moisture years the above ground vegetation could burn and the organic soils would remain in place. In years of severe drought when the swamps were excessively dry the organic soils become available fuel and burned down into the ground. Our local belief is that there was a severe fire year, many years ago, and it burned the organic peat down to mineral soil (sand) and the vegetation and organic soils have never recovered, thus we have roundish or oval lakes. If you take into account the prevailing wind direction when we have summer fires (out of the east, south-east) you have some directionality of the way the fire would move and possibly why the lakes are shaped the way that they are shaped.