The Lake Anna Quarter is found above the man made Lake Anna, Virginia which is a reservoir. This image was shown on StumbleUpon when i accidentally clicked the wrong button.
It looked to me instantly like a crater lake, a rim shot crater. The curving upwards of the top sides towards the mouth is very interesting and so is the missing front bit which is also curved. It reminded me a bit of the Malta’s circular crater Bays that curve upwards also.