Freeze Thaw cycles typically produce forms that are hexagonal in shape, not elliptical. I can’t say what these elliptical shapes are, but they do not look like anything formed by freeze thaw.
Ten thousand years of ADDITIONAL weather can do a lot of stuff ~ the circles are known in other places.
The other difficulty with the freeze-thaw theory is that, in the Carolina coastal plain where these bays are found, you'd be hard-pressed to find a rock. The nearest loose rocks to be found are probably fifty or a hundred feet straight down, or westward to the nearest granite upthrust (about to I-95).