The first aerial photo of Carolina Bays, taken in 1930.
Source: http://abob.libs.uga.edu/bobk/cbaymenu.html

As I was scanning North Carolina, I saw something that brought to mind a term that I haven't heard since I was majoring in geology 40 years ago - Carolina Bays. (An achievment in itself for someone who often can't remember where the car keys are). I typed the phrase into Google, and got multiple hits - it really was the term to describe what I was looking at. One interesting thing about these oriented oval structures is that geologists are still not sure of their origin. Their signifigance wasn't discovered until the 1930's when aerial photography revealed their true nature. I think the strongest hypothesis is that they are of extra-terrestrial origin, caused by a comet nucleus that broke up in the atmosphere, scattering pieces that gouged out depressions which are all oriented in a NW-SE direction. But there are other theories, some plausible, some unlikely. Click the "web page" links to take you to further discussion of the Carolina Bays. web page 1 web page 2 web page 3 web page 4
web page 5
For more information about this and similar phenomena, go to http://www.perigeezero.org

Source

Orientation of the bays points back to a common point of origin to the northwest.