The glacier ice boulders that made the Carolina Bays traveled in ballistic trajectories with
a range of 1500 kilometers and had loft times of six to nine minutes.
This is sufficient time for the rotation of the earth to affect the landing point of the
ice projectiles.
The alteration of the trajectory by the rotation of the Earth is known as the Coriolis Effect.
Welcome to another edition of the Carolina Bay of the Day where we study the secondary
impacts made by the glacier ice boulders that were ejected by an extraterrestrial impact
on the Laurentide Ice Sheet.
There is a link to the LiDAR visualization tool for Google Earth by Michael Davias in
the description of the video.
This presentation will examine the effect of the rotation of the Earth on the emplacement
of impact basins in Georgia.
The Glacier Ice Impact Hypothesis, published in 2017 proposes that an extraterrestrial
impact on the Laurentide Ice Sheet by the Great Lakes ejected pieces of ice in ballistic
trajectories.
The secondary impacts of the glacier ice boulders produced inclined conical cavities with raised
rims that were transformed into shallow elliptical basins by viscous relaxation.
The impact basins have elliptical geometry because they originated as inclined conical
cavities, and they have raised rims because they are the result of impact cratering which
forms the rims by compressive horizontal forces when the projectile penetrates the target.
The major axis of the impact basins is oriented toward the Great Lakes because Saginaw Bay
is the convergence point of the Carolina Bays and the Nebraska Rainwater Basins.
The terrain in Georgia is rougher than in the terrain in North and South Carolina, so
it has a fewer impact basins.
Water erosion degrades the impact basins very quickly and today they are only found on the
tops of hills that have a relatively flat surface.
Inclined terrain cannot retain the sandy structures of the impact basins.
This impact basin is approximately 29 kilometers or 18 miles southwest of Augusta, Georgia
and 186 kilometers or 116 miles from the Atlantic Ocean.
The center of the basin has an elevation of 130 meters above sea level.
The impact basin does not have the expected elliptical geometry because it is on inclined
terrain.
Basins on inclined terrain are usually deformed on the uphill side because soil flows into
the steeper grade of the cavity during viscous relaxation.
The colorized topography indicates that the rim of the basin on the north side is about
4 meters higher than the center of the basin.
The heading of the major axis of the basin is 171 degrees.
This is the direction from which the ice boulder that made this basin originated.
Extending the major axis of the basin with the heading of 171 degrees takes us back very
close to Saginaw Bay.
The Carolina Bays, the Nebraska Rainwater Basins and most other impact basins are found
within a circle with a radius of 1500 kilometers from Saginaw Bay.
Notice that the circle extends into the Atlantic Ocean.
At the time of the extraterrestrial impact, 12,900 years ago, the sea level was about
50 meters lower than it is today.
No evidence remains of the impacts made on the terrain that is now covered by the ocean.
This image shows the trajectory from Saginaw Bay to its destination in Georgia as a straight
line, but it should be shown as slightly curved by the Coriolis Effect.
The National Geographic resource library says that the Coriolis effect describes the pattern
of deflection taken by objects not firmly connected to the ground as they travel long
distances around the Earth.
This model illustrates that the linear motion of an object against a rotating disk appears
to trace a curve on the rotating disk.
This is the Coriolis Effect.
We can calculate the effect of the Coriolis effect on the emplacement of the Carolina
Bays by considering that the Earth is a rotating sphere with a circumference at the equator
of 40,070 kilometers.
Since the Earth makes one complete revolution once every 24 hours, the rotational speed
at the equator is 1670 kilometers per hour or 464 meters per second.
The rotational speed of the Earth varies by latitude.
The speed at any latitude can be calculated by multiplying the cosine of the latitude
times 1670 kilometers per hour.
The rotational speed decreases toward the northern latitudes and it is zero at the poles.
Launching satellites from points closer to the equator takes advantage of the rotational
speed of the Earth and requires less rocket fuel than launching from points further away
from the equator.
The flight time of the glacier ice projectile from Saginaw Bay to its destination in Georgia
was 481 seconds.
This calculation is discussed later in more detail.
The surface of the Earth at the latitude of Saginaw Bay has a rotational speed of 334.8
meters per second, and the rotational speed at the latitude of the Georgia basin is 387.9
meters per second.
Multiplying these rotational speeds by the flight time of 481 seconds gives a difference
of 25.6 kilometers.
This is the distance by which the ballistic flight of the projectile was deflected from
its original target due to the Coriolis Effect.
This image illustrates the path of the ice projectile at the time that it was launched.
The Earth's rotational speed at Saginaw Bay is 1205 kilometers per hour.
That is about 749 miles per hour.
However, the Earth's rotational speed at the latitude of the Georgia target is 1396 kilometers
per hour.
That is about 867 miles per hour.
By the time the projectile hits the ground, the Earth has moved 25.6 kilometers toward
the east.
The trajectory looks curved relative to the Earth, but here the curve is exaggerated for
illustration.
The difference of 25.6 kilometers in the location of the impact is only an angular difference
of about 1.2 degrees in the trajectory due to the Coriolis effect.
The small deflection is due to the short duration of the ballistic flight.
This impact basin in Georgia is located 1192 kilometers from Saginaw Bay which is assumed
to be the point from which the ice boulder that made the basin was launched.
The basin has a width of 562 meters and a length of 815 meters.
Notice that for the calculation of the projectile size we use the length of the major axis of
the ellipse, which corresponds to the dimension of the original conical cavity before viscous
relaxation altered the shape of the basin.
The width-to-length ratio corresponds to an impact angle of 43.6 degrees.
The diameter of the glacier ice projectile that made the basin is estimated to be 163
meters, which is one fifth of the basin length.
The ballistic equations indicate that the glacier ice boulder that made this impact
basin was launched at a speed of 3.421 kilometers per second.
It had a flight time of 8.02 minutes and reached a height of 284 kilometers above the surface
of the Earth.
This is an illustration of the launch angle, the range, and the height of the ballistic
flight.
The atmosphere is only 100 kilometers thick, so the trajectory was a suborbital space flight
in the vacuum of space.
The kinetic energy of the impact was equivalent to 2.9 megatons of TNT, which would have caused
seismic vibrations of magnitude 7.79.
If you have been paying attention, you probably noticed that Wright Allen Road goes right
across the southern rim of this basin.
We can see what this looks like by using Google street view.
Heading southeast on Wright Allen Road, we see that the terrain is lower on the left
side of the road and higher on the right side of the road.
Notice that the road is slightly elevated to prevent it from being flooded during rainstorms.
Without the LiDAR image that gives us a broader perspective, we could think that this is just
a gentle hill and not the rim of an impact basin measuring 815 meters or half a mile
in length.
The examination of this impact basin in Georgia showed that the Coriolis Effect had a minor
but measurable influence on the location of the secondary ice boulder impacts.
We also got to see that the rough terrain in Georgia makes it difficult for the impact
basins to resist the powerful erosive action of the rain.
Thank you for joining me in the investigation of the Carolina Bays and the Younger Dryas
cataclysm.
I will continue to examine the Carolina Bays one bay at a time.
My book about the Carolina Bays is available at Amazon.
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Bays.