What does a geologist say about the Carolina Bays?

One of the first geologic maps I worked on after starting my current job had Carolina Bays in the coastal plain portion of the map. That was the Cherry Hill quadrangle near Emporia, VA. I had never heard of them before that map.

I didn't realise geology could be so contentious. I'm pretty sure if this Zamora person invited some of these people over for Kool-Aid they would definitely drink it.

I was so waiting/hoping for the Lana Delta to come into this discussion. I became aware of them while researching the voyage of the Jeanette, an early attempt to reach the north pole. George de Long and his crew landed there after the ship became trapped and crushed by sea ice.

This a an interesting analysis, and, if you are interested Pleistocene climate, serves to suggest that the climate might have been far harsher than we normally imagine. The large, partially eroded "bay" discussed around 11:00 shows multiple concentric lines of vegetation along the lower right. Those look like shore line features and might indicate the feature, which is only partially defined, might in reality be sequential meander margins of a stream migrating up and left in the image. With LiDAR it should be poissible to detect relict thermokarst landscapes even in heavily forested environments. The eastern seaboard and plains were heavily forested prior to European colonization. The Lena River example also includes meandering streams that are not incised.

Wouldn't the energy of an impact melt chunks of ice that got blasted off the ice sheet? Especially if they became sub-orbital during their re-entry?

Toward the end of the video when you show the lakes in alaska, those are thermokarst lakes and they've been proven to not have regular elliptic shape or directional orientation like the Carolina bays.

Cool stuff man. I like how people are explaining your profession to you. Seems like a very complex combination of data. No simplistic conclusion.

a couple things come to mind as watching this. regarding the dividing line where 2 bays overlap, I dont think a comparison to celestial impacts is not valid. I think if there are too many to be cosmic impacts, they would have to be secondary impacts of ice. ice thrown off of a glacial impact would be a fraction of the speed and likely fractured at a low angle I think the impact energy would be low. the direction is something to note, not all but most clusters are. the melting ice would cause an extremely flat floor. plus these things are just different. the other ones around the world dont fit to me, I dont think there is enough similarity to call them the same

As I recall, all of the versions of the impact theory I've learned of involve multiple primary impacts in quick succession, some simultaneous, that each generated their own secondary "splash" events that are proposed to have created the "bays". The ideas were of one or more objects that broke up before impact, possibly colliding shortly before impact, or perhaps even a swarm of smaller objects to begin with. Some have compared the event to the various annual meteor showers we experience on Earth as our orbit takes us through debris fields.

There is a possibility that at least some of the impacts were from liquid instead of solid ice because the speed of the event might have melted the ice. Geology like archaeology changes slowly, and new theories are hard sells. The continental drift theory was widely rejected until the 1960s.

Lacking a crater maybe it was not a solid impactor but instead was something in liquid/steam? Imagine a comet breaking apart and the large chunks of ice explode just before impact and create airbursts Like a gigantic pressure washer where the droplets are tens or hundreds of kilograms in mass.

I agree with impacts being simultaneous, but might they be over a few minutes in delay due to trajectories?

The bay had to be there to form the sand sheet? No, the sand sheet had to be there and still be active at the time the bays formed.

Aeolian scientist here: I'd suggest that the parabolic dunes you show at 10:00 (and again a few times) likely predate the bays. Why I think this: - The dunes are roughly the same size as those nearby (across the river, for example) that aren't connected to bays. Dunes of similar size like this tend to have formed in the same time frame, from the same wind patterns, with the same influx of sand. Of course dunes can be reactivated so this can get tricky. - The deep bay in the upper center seems to have degraded dune deposits to its west, which would be upwind rather than downwind. Although you could argue that those are derived from the next bay to the west (the one with a stream channel). - The deposits (lunettes maybe?) downwind of the bays tend to be on their SE side, suggesting a ~NW wind formed them. However the parabolic dunes were formed by a SW wind. To me this suggests that the bays and parabolic dunes were formed at different times when the strongest winds blew from different directions. (It could also be a seasonal thing: if the bays are related to ice like those in Alaska/Russia then they'd be shaped by winter winds, whereas the parabolic dunes could be shaped by summer winds when the landscape dries out enough to mobilize sand.) Either way, these things are very cool and a wonderful mystery. I just think that this particular location shows bays crosscutting dunes. The example you show at 11:30 clearly shows dunes crawling on top of a bay, so I agree that their history is intertwined. Thanks for the close look at these things!

A very cool video. Thanks. Has anyone excavated a trench across one of the bays? I would expect at least a thin layer of finer sediment deposited under water in the middle? I guess it depends on how long they were water-filled before draining. Still a likely to trap for spores or pollen blown up from the South?

Hydrologically closed bays don’t cooperate with the dune progression. If they have been naturally drained by being pirated (like Big bay), they accept the dune moving in. Check it out … seen in numerous instances.

I like the theory of glacial ice from a meteor empact falling back to earth. This would leave no trace of the impact debris.

Dismissing their orientation without assessing it statistically suggests his bias instead of open interest. His other examples of aolian formed depressions, he states they show similar alignment where clearly they do not. Where I agree with him is if the central area is undisturbed strata, that would convincingly disprove impact formation....evidence?

They look just like all of northern Alaska from just south of Point Lay to just east of Prudhoe Bay. Looks like a spray of meteor fragments that landed there too. They all lay in the same direction as well, like there was an impact north west of there? Would be interesting to see it in Lidar.

I wonder if the craters could've initially been sand boils