Carolina bays, Vernal Pools and Ephemeral Pools

The Carolina Bays
This is one of the photographs that started the controversy over the origin of the Carolina bays. Certainly, early settlers were somewhat aware of the curious nature of these areas, but until aerial photographs were published, both their consistent oval shape and their vast distribution were unrecognized.

The Perigee-Zero conjecture suggests that rather than being structures created by impacting extraterrestrial objects, the bays are instead the manifestation of terrestrial ejecta lofted from a distant impact site. Our explanation of these structures is discussed in the Ejecta Morphology section of our site.

We suggest to the reader that in this black & white photograph, the nature of the bays as "splash" structures is apparent. Also apparent is the shape; it is not oval, but more of a tear-drop, with one end being narrower than the other.

It is believed that there are more than 500,000 "Carolina bays" identified in the southeastern USA. But the phenomena is not restricted to this area alone. The photo below is what we consider to be a classic Carolina bay. Teardrop in shape, with a raised rim, no obvious water inlet or outlet, and effectively standing above the surrounding terrain.

Perfect

This structure is located in the Minneapolis- St. Paul MN area. A close examination of the many lakes in the immediate area show a high correlation to the Carolina bay characteristic structure.

Please note that this structure displays an interesting emplacement artifact. The ejecta droplet involved arrived from the upper right (NNE) in this image. The ejection site is therefore to the north of the emplacement site. The droplet's velocity has a west-to-east vector component that represents the ground rotation velocity at the ejection site, but the ground here is moving west-to-east at a higher velocity. As a result, the entire emplacement is effectively compressed on the western (left) side. This creates a structure that is not symmetrical across the major axis. This artifact allows for another correlation between an emplaced object and the physics of transporting it to the emplacement site.

For further visual exploration, the reader is referred to George A. Howard's web site, which offers a wonderful set of arial photographs of Carolina bays.

There exists an extensive body of work attempting to identify the natural process responsible for creating the anomalous landforms known as “Carolina bays”, Vernal pools or ephemeral pools. Some of the hypotheses suggested for the formation of the bays are listed by Price (1968a, p. 103):
. 1 Spring basins
. 2 Sandbar dams of drowned valleys
. 3 Depressions dammed by giant sand ripples
. 4 Craters from a meteor swarm
. 5 Submarine scour by eddies, currents, or undertow
. 6 Segmentation of lagoons and formation of crescentic keys
. 7 Lakes in sand elongated in the direction of maximum wind velocity
. 8 Solution depressions, with wind-drift sand forming the rims
. 9 Solution depressions, with magnetic highs near bays due to redeposition of iron compounds leached from
basins
. 10 Basins scoured out by confined gyroscopic eddies
. 11 Solution basins of artesian springs with lee dunes
. 12 Fish nests made by giant schools of fish waving their fins in uni. 13 Eolian blowouts (deflation)

Easily identified by their characteristic elliptical shape, these small lakes in the eastern US have frequently been evaluated for a wide range of impact characteristics. They have proven to be inconsistent with landforms formed in situ by a foreign impactor.

Carolina Bays do not even closely approximate impact crater morphometric characteristics. The rim widths appear to be the only measure which even falls within the range predicted by the impact model. In an attempt to examine this phenomenon, a curve relating rim height and rim width was derived from Baldwin's curves and the values for the bays in Table 5 were plotted (Figure 3b). For an impact crater to have a rim height of 7.5 feet, it should have a rim width of 100 feet.

Junkyard Bay has a mean rim width of 575 feet with a mean rim height of only 7.4 feet. In all nine bays, rim width is considerably greater with respect to rim height than the model predicts. As impact structures, the Carolina Bays exhibit crater depths that are much too shallow for their diameter, rim heights that are too low for their diameter, and rim widths that are too narrow for their diameter. The rim widths are considerably wider than is expected with respect to the actual rim heights.

Clearly, the bays are not impact phenomena of the type that created the lunar and terrestrial craters. Additional terrestrial Carolina Bay characteristics such as the absence of coesite and stishovite (Si02 polymorphs), the lack of any meteorites genetically related to bays, and the elliptical, rather than circular form of the bays, also do not support any traditional type of extraterrestrial impact bay formation model.

From “A RE-EVALUATION OF THE EXTRATERRESTRIAL ORIGIN OF THE CAROLINA BAYS” by J. Ronald Eyton & Judith I. Parkhurst, Paper Number 9 April 1975 Luis E. Ortiz & Susan Gross, editors Geography Graduate Student Association University of Illinois at Urbana Champaign

Evaluation of the profile of the bays has identified them as having ages of 7,000 to 50,00 years. The graphic below illustrates the findings from the carbon dating of core samples from the Flamingo bay, by Brooks, Taylor & Grant. A linear extrapolation would put the bottom sediments dated at 12,000 yr B.P.

flamingo_bay_stratigraphic_section

The paper concluded that:
  1. Significant modification of the bays, including rim development and basin infilling, occurred during the Holocene
  2. ponds on the early Holocene landscape were larger and more permanent than at present
  3. early Holocene climate, as indicated by both depositional processes and human activity, was not characterized by prolonged periods of extremely dry conditions; and
  4. fluvial-centric models of terminal Pleistocene-early Holocene human adaptations require revision to include intensive use of isolated upland ponds.


An evaluation of Carolina bay geology is offered in an extended excerpt from the South Carolina Maps and Aerial Photographic System's web site at Clemson University. We encourage the reader to review this document for interesting historical and geologic content. The following excerpt we find particularly informative:

Carolina Bays have characteristic soil assemblages which are the result of the very moist conditions commonly found in these environments and which can be distinguished easily from one another and from surrounding soil types on aerial photographs. Wet soil generally appears darker due to the greater accumulations of black organic matter. However, when winter cover crops have been planted, wetter soils usually support more vigorous plant growth and appear a deeper red or pink on infrared photographs than drier soils. Soil mapping surveys, such as those run by the United States Department of Agriculture, commonly draw boundary lines, delineating different soil types, directly on aerial photographs while working in the field. These surveys look at factors such as landscape position, shades of bare soil, types of vegetation growing on the soil, and water drainage patterns commonly found on that soil. Although not all soils can be so easily determined, the unique soils of the Carolina Bays can usually be separated and identified on a variety of remotely sensed images. Three distinct soil types are found in most of the larger Carolina Bays:

  1. PONZER - This is often the dominant soil in large Bays, and it is also found in the center of smaller ones. Due to the lack of oxygen caused by water saturation, which slows decomposition, this soil is almost all organic matter. The soil microbes which would normally cause complete decomposition need oxygen to break down the leaves and other plant litter that fall to the soil surface. Over the years, an organic rich "A" horizon layer accumulated that is several feet thick. This soil appears dark in an aerial photo. While some pine trees can grow in it, they cannot compete well with better adapted deciduous vegetation. When drained, this is a highly productive agricultural soil.
  2. RUTLEDGE - This soil is found along the inside of the boundary of large Bays and occupies most or all of the area of smaller Bays. It is slightly higher in elevation than Ponzer soils and is therefore slightly drier. It also has a high organic matter content but is much more sandy. It also more easily supports loblolly pine trees. Rutledge soils also make productive agricultural land when drained. The land appears dark in an aerial photo, but not as dark as Ponzer. In Infrared aerial photos (taken in winter), Rutledge soils will appear much redder than Ponzer due to the abundance of evergreen trees such as pines.
  3. RIMINI - This soil is sometimes found on the sandy rims of Carolina Bays. It is a rather unusual soil in that its subsurface "B" horizon layer is full of organic acids combined with aluminum atoms that leached from overlying horizons. While the surface color can be bright enough to appear almost white, the color of the "B" horizon layer is often brown or black, like topsoil, but it is found about four feet below the soil surface. [Soils of this type are usually found in northern regions, like New England, Northern Michigan, Minnesota, and Canada.] For several reasons, including acidity and possible aluminum toxicity, this is not a good soil for plant growth and is only sparsely covered by scrubby pines, blackjack oak, and turkey oak. This is not an extensive soil, and is almost never used for agriculture. It appears very light in an aerial photo due to the high sand content and dryness of the soil surface.

We have emphasized the bracketed comment in the last paragraph. The Perigee: Zero research suggests that the site of the cometary impact creating the generic southeastern seaboard Carolina bay ejecta was excised from the area of lower Lake Michigan.
NASA has weighed in on the dialogue using the LANDSAT remote sensing tool. A brief presentation is available online. Included in that paper is the following

No investigator has disputed the influence of eolian processes as an agent in bay formation. The question is whether the wind action is primary or secondary. The high reflectivity of the rim sand dunes outlines many of the bays on the Landsat image and can be clearly seen in the ancillary photos (Figure KL-10.1, Figure KL-10.2, and Figure KL-10.3). Many of the dunes are believed to be former longitudinal dunes that later, under the influence of more humid conditions, transformed into parabolic dunes or blowout crescent- shaped dunes with tails anchored by vegetation (Price, 1968b). Because today ́s dominant winds blow from the southwest, a more complex wind regime than that suggested by either Thom or Price must be invoked to account for the buildup of sand on the southeast ends. Such wide variation exists among the half million lakes that no single hypothesis satisfactorily explains their origin. Landsat 1080-15203-5 October 11, 1972.

Here we have hi-lighted NASA's deduction that a complex wind regimen would be required to have been the primary factor in Carolina bay geomorphology.

While many identified Carolina bay structures lie in flat terrain, an interesting scenario is found in the Goldsboro Ridge Structure, discussed in the Enigma Section.

trajectories
Carolina bay Orientation - Eyton & Parkhurst

Our analysis correlates these structures - including the Goldsboro Ridge - to a Perigee: Zero cometary impact event that struck the Wisconson-era ice shield between 10, 000 and 17,000 years ago. The general "rotation" of inbound ejecta trajectory represented in the Eyton & Parkhurst graphic is the manifestation of two different factors. The first being the the Earth's rotation during the loft period applied to the main body of bays pointing NW. Ejecta droplets traveling on a more southerly bearing will land slightly further westwardly due to the faster west-to-east ground rotation vector. As a result, their azimuth will "seem" to be directed back towards a point further west than the actual ejection point. This effect will revers if the emplacement site is further towards the pole than the ejection site.

The following Google Earth graphic is our projected trajectory path for this set. The Lake Michigan impact will be discussed in the the Lake Michigan Series proof set.

Perigee: Zero ejecta has created millions of freshwater bodies throughout the world. We present a sample in our Ejecta Gallery. Keep in mind when viewing these that the characteristic shape of PZ ejecta is typically found with amazing fidelity, regardless of the scale of the structure.