As of this writing in May 1999, the Carolina Bay phenomenon remains a geomorphologic mystery. The heyday of research into the origin of these features was in the middle part of this century, and no serious field work has been performed in over 20 years. Most of the research now being done involves the study of the characteristics, health, and preservation of the bays’ unique ecosystem, which are highly threatened by human land uses, both urban and rural.
What has caused this lack of interest in the origin of the bays? While compiling a literature review on the subject, it was apparent that none of the researchers ever arrived at a definitive causal mechanism for the bays’ existence, and the more I thought about the differing theories of their origin, the more puzzled I became. What process is responsible for their creation? And then it dawned on me that perhaps the reason that the research has shifted towards the preservation of these features is because they are threatened, and the pure scientific inquiry of uncovering their genesis seems relatively unimportant. In other words, the scientific priorities have shifted due to human-cultural reasons, and it’s probably for the best that researchers have focused on their preservation. Carolina Bays are sensitive areas, and considering that more than 97 percent of the Carolina Bays once found in South Carolina have been destroyed or severely altered, it should be no surprise that not much research into their origin has been conducted (SREL, 1998).
If one examines the process of scientific inquiry and discovery, it is apparent that science rarely is conducted in a streamlined, cohesive fashion. As it presently stands, no one knows for sure how the Carolina Bays were formed, or even specifically when they were formed. To the credit of science, it is still a relatively young mystery; the aerial photograph that kicked off the discourse was disclosed in 1933. I believe that at some point, research into the bays’ origin will resume. By conducting this literature review, it is my hope that the paper will serve as a useful guide for anyone interested in conducting research into the subject. I intend to have it (or some form of it) published on the web at a relevant site. I’m also hopeful that this topic could become a possible research topic in the future. The review consists of an outline of the definitions of the Carolina Bays, a review of pertinent theories regarding their origin, an outline of present research, and suggestions for future studies.
What are the Carolina Bays?
The Carolina Bays are small oriented depressions, elliptical to ovate in shape, that dot the south-eastern coastal plain of the United States in incredible density and range.
Range: They extend from the Delmarva Peninsula in the north (some researchers claim to have identified Carolina Bays as far north as southern New Jersey, although the claims appear to be unconfirmed), to the Okefenokee swamp in Northern Florida. The area of the greatest density is in the counties of Harnett, Sampson, Cumberland, Hoke, Robeson, and Bladen, south-eastern North Carolina.
Quantity: There are an estimated 500,000 Carolina Bays (Prouty, 1952).
Age: Radiocarbon dating conducted by Whitehead, 1967, indicates that material, at depths of 2.3-2.34 meters in Singletary Lake, are at least 40,000 years old. Material from 1.04-1.07 meters are at least 5,750 years old (Kaczorowski, 1977). Similar studies more or less agree with these dates.
Attributes: From Johnson, 1942, and Prouty, 1952
Theories of Origin:From Price, 1968
Spring Basins Toumey, 1848, pp. 143, 144)
Sand bar dams of drowned valleys (Glenn, 1895)
Depressions dammed by giant sand ripples (Glenn, 1895)
Craters of Meteor Swarm (Melton and Schriever, 1933)
Submarine scour by eddies, currents or underflow (Melton, 1934)
Segmentation of lagoons and formation of crescentic keys (Cooke, 1934). Original hollows at the foot of
marine terraces and between sand dunes (Cooke, 1954, p.195)
Lakes in sand elongated in direction of maximum wind velocity (Raisz, 1934)
Solution depressions, with wind-drift sand forming the rims (Johnson, 1936)
Solution depressions, with magnetic highs near bays due to redeposition of iron compounds leached from basins
Basins scoured out by confined gyroscopic eddies (Cooke, 1940, 1954)
Solution basins of artesian springs, with lee dunes. (Johnson, 1942)
Fish nests made by giant schools of fish waving their fins in unison over submarine artesian springs (Grant, 1945)
Eolian (deflation) blowouts, reported by Prouty (1952) as suggested by a "number of scientists", supported by Kaczorowski, 1977
Cometary fragments exploding above surface, their shock waves creating depressions (Eyton and Parkhurst, 1975)
Unfortunately, literature on the Carolina bay topic is extremely difficult to obtain, even at a major public university such as San Francisco State or UC Berkeley. Nonetheless, I was able to obtain several pertinent sources, including D.W. Johnson’s 1936 article, " Origin of the supposed meteorite scars of Carolina. Science 84: 15-18.", RT Kaczorowski’s 1977 Technical report, " The Carolina Bays and their relationship to modern oriented lakes. Geol. Soc. Am. Abstr. 9: 151-152.", B.G. Thom’s, "Carolina Bays in Horry and Marion Counties, South Carolina", Geol. Soc. Am. Bull. 81: 783-814, W.F. Prouty’s "Carolina Bays and their Origin", Geol. Soc. Am. Bull. 63: 167-224, and Eyton and Parkhurst’s "A Re-Evaluation of the Extraterrestrial Origin of the Carolina Bays" University of Illinois, 1975. In addition I have read and reviewed Savage’s, "The Mysterious Carolina Bays", USC Press, 1982, which is an overall summary of the Carolina Bay literature intermixed with Savage’s own views on the subject. Unfortunately, I was unable to obtain Johnson’s definitive work, "The Origin of the Carolina Bays", which would have greatly added to the validity of this literature review. The intention of this paper is to summarize the key points of each author (except Savage) as they relate to the greater discourse. I will do this chronologically, beginning with Johnson in 1936.
Origin of the Supposed Meteorite Scars of Carolina
D.W. Johnson, 1936
This brief article appeared in Science only three years after Melton and Schreiver wrote about the meteoritic theory explaining the genesis of the bays. It was the first paper that refuted the extraterrestrial origin in favor and instead offered a hypothesis that the bays were of terrestrial origin after all. Johnson, at the time, was preparing a volume on the subject, and thought it necessary to inform the public of the progress he was making.
Johnson succinctly describes the state of the controversy before offering some summaries of his observations of bay attributes during field work he conducted in conjunction with W.F. Prouty, his friend, but main "opponent" in the discourse. He then offers his working hypothesis of bay genesis, " The Depressions are due, directly or indirectly largely to solution of calcareous beds at varying depths below the surface, but possibly in smaller measure to the solution of alumina and iron in arkoise beds after the manner described by Smith" (Johnson, 17.). Johnson then attributes the shapes and orientation of the bays, as well as the presence of the sandy rims to wind and wave action.
Lastly, he explains how artesian springs, found in several bays that were, at that time, still lakes, could have formed these depressions by creating gaps through the underlying loamy strata, and forcing subsidence. He explains the existence of the rims as the remains of the artesian process, which would carry out the finer particles of silt and clay into outlet streams. All of the information in the article appears with a disclaimer as a working hypothesis, which requires further scrutiny.
This paper is a decent starting point into a literature review but I would rather have reviewed his definitive work which came out six years later. By then, Johnson had had his hypothesis heavily scrutinized by several parties, most notably Prouty. Johnson adjusted his hypothesis to the scrutiny. He imagined a time when the sea had withdrawn from the coastal plain, the rivers had not yet developed their valleys, and the climate was extremely wet. The water infiltrated the ground creating very high water tables in the piedmont. As the groundwater traveled downslope towards the sea, the pressure built up and eventually was strong enough to generate cracks in the aquacludes above, and through the process of solution of calcareous rock, deposition of coarse quartz sand, and the removal of finer particles, the Carolina Bays were born.
Carolina Bays and Their Origin
W.F. Prouty, 1952
This article was the culmination of twenty years of research into the Carolina Bay phenomenon and is considered the best descriptive article on the subject. Its entire list of bay attributes has already been printed in this paper in combination with the observed facts gathered by Johnson.
Prouty begins the paper by concisely describing the bays, the theories regarding their origin, and his own theory. He then devotes approximately 20 pages to a detailed description of bays based upon his field research describing the age, geology, distribution, vegetation, and terrestrial processes that affect the bays. After that, several pages are devoted to discussing, in detail, each theory of origin and what is wrong with each one (including the original meteoritic theory). Finally, Prouty introduces his modified meteoritic theory. Prouty was an original proponent of a meteoritic theory of the genesis of the bays, which originated in 1933 with Melton and Schriever, was modified by Prouty in 1936, and further modified by Prouty by 1952. The modified meteoritic theory can be summed up as follows: a comet or asteroidal body, entered the earth’s atmosphere at an oblique angle (roughly 35 degrees) (Prouty, 217) from a relative northwesterly direction. Due to friction, it disintegrated in the atmosphere, sending smaller projectiles hurtling towards earth. As the projectiles fell, the air pressure rises creating a cone shape shock wave with the projectile as the apex. The projectiles varied in size, but were probably very small by the time they reached impact. The pressure cone, however, was extremely powerful and explosive as it traveled trough the atmosphere. Prouty believed that the shock waves from the pressure cones were responsible for the initial development of the Carolina Bays.
Following the introduction to the theory, 13 facts are listed that apparently could be explained by his theory only (which are, incidentally, the 13 last attributes listed on page 3). He then gives a detailed description of the various field studies he conducted in support of his hypothesis beginning with the magnetometer studies which he believed confirmed the meteoritic theory of bay origin. Studying 26 bays, Prouty discovered that each bay appeared to have an associated magnetic high usually located a few degrees to the south of the orientation of the bay’s long axis. From the data, Prouty constructed isogamic maps (but did not adequately explain his interpolation methods) to construe his data. His results clearly show the associated magnetic highs, although later researchers questioned the methodology he utilized.
Prouty constructed a trajectory model with a high powered rifle, some Plaster of Paris, coarse white sand from a bay rim, and some flour. His hope was to model impact and measure the shape and depths of the resulting impact structures and compare them to the Carolina Bays. He used material of different depth and consistency to model local stratigraphic and soil variances. In each case, he was able to recreate a primordial Carolina Bay, complete with ellipticity and orientation.
Prouty also spent considerable time in the field classifying, measuring, and characterizing bay shape and orientation. In this study, heart shaped bays, which were shown by Prouty to actually be one bay overlapped by another, played a key role. He reasoned that no terrestrial theory could account for their odd morphology, and were the results of the infall of tandem meteorites (p.222). He also believed that the orientation of the bays played as key role in support of his theory. In the Delmarva Peninsula, bays have an average orientation towards a little south of east, or approximately 100 degrees of azimuth from north. Further south, in the areas of the densest concentrations of bays, the average azimuth is somewhere between 120 and 150 degrees. In southern Georgia and Northern Florida, bays are oriented a little east of south, or between 170 and 185 degrees of azimuth. The bays also show differences in shape and orientation as one moves from east to west within the distribution. All of this was attributable, Prouty thought, to the relative motion of the earth’s rotation to the comet’s trajectory (Prouty, 222).
Prouty concludes by suggesting a need for more data, not uncommon advice for any scientist, particularly in field work concerning the orientation of the long axes and the magnetometer studies. He concedes that solution, wave action, and wind action were very important geomorphic agents in Carolina bay morphology, but only after they were formed. None of those processes, he stated, could account for their origin.
Carolina Bays in Horry and Marion Counties
Bruce G. Thom, 1970
Almost twenty years after Prouty’s volume on the Subject, Bruce Thom, a geomorphologist at Lousiana State University, produced a detailed study on the origin of Carolina Bays in two coastal counties in northeast South Carolina. Thom spent about five years researching the topic in the field, and his results carried high credibility within the scientific community.
The study is based upon the premise that a detailed analysis and mapping of the geology, stratigraphy, and landforms had not been previously attempted on a constricted regional scale, and therefore lacked some credibility. Thom limited his study area to two South Carolinian coastal counties, Marion and Horry. He believed that there was a regional pattern in Carolina Bay distribution, and that it was a reflection of the local terrain. From his observations, Thom suggests that the bays originated solely from terrestrial forces.
The paper begins with a detailed description of the geomorphology of the study area, which is generally a plain dissected by rivers flowing out of the piedmont or Blue Ridge, and flat interfluves between rivers. The area shows the past history of sea level change as thousands of beach ridges line the study area in a general northeast/southwest trend. Ancient dune fields dot the areas between the beach ridges. Thom conducted several boring experiments to determine the stratigraphy, which he was able to classify into various types, formations, and materials.
From his field research, Thom was able to categorize three types of Carolina Bays, according to which landform they occupied: flat interfluve (the most common), dune depression, and terrace contact. All of these landforms are sand rich and Thom did not discover bays on any other surface type (Thom 783). These observations led Thom to conclude that the bays are actually reflective of the local terrain environment, and must originate from terrestrial forces.
To explain this, Thom constructed a theory that was based upon the existence of a material he called humate, which is a sticky, mud like substance that is actually impermeable. In his coring samples, Thom discovered that each bay within the interfluve category was underlain by humate (Thom, 783) close to the surface. What happens, he reasoned, is that the humate allows for a perched water table near the surface that would eventually evolve into shallow, wet depressions, orientated later by wave and wind action. The bays not found in the interfluve areas originated from Wisconsin aged shallow lakes when "vegetation cover and drainage systems were undergoing considerable change" (Thom 783).
Even though Thom spent nearly five years on the Carolina bay problem, and limited his study area to just two counties, he admitted that his results were somewhat inconclusive. He suggested that a further study should concentrate on stratigraphic drilling, magnetometer studies (to verify Prouty), the extent to which solution was a factor in the process, and the extent to which wind and wave action influenced the formation of the bays. He also suggested that a relevant study might incorporate regional comparisons of the oriented lakes of northern Alaska. His suggestions would not go unnoticed.
A Re-Evaluation of the ExtraTerrestrial Origin of the Carolina Bays
J. Ronald Eyton & Judith I. Parkhurst, 1975
This article was written with intentions to seriously discuss the possibility that an extraterrestrial body did indeed impact the earth and create the Carolina Bays. Due to the trend towards acceptance of a terrestrial origin within the scientific community, these University of Illinois geography graduate students felt it necessary to reintroduce the theory first introduced by Melton and Schreiver, and modified by Prouty some twenty-three years earlier. The authors accomplish this task without doing any field research, but instead examining the probability of impact from different objects and the physics involved if an impact as causal mechanism is assumed.
The paper begins with a brief explanation of the authors’ motives for the study followed by a description of the bays derived largely from Prouty. It then shifts to a discussion of the opposing theories up to Thom’s study, which, at the time, was the most recent study available. The paper quickly shifts to a discussion of extraterrestrial bay forming mechanisms.
The authors state that there are essentially three bodies which could have possibly been responsible for the bay genesis: asteroids, meteoroids, and comets. The orbital characteristics of each group was analyzed, and from this analysis, the authors concluded that meteoroids, such as the ones that comprise the spectacular Leonid shower, were unlikely to have existed in sufficient numbers or have enough mass to survive passage though the atmosphere to create half a million Carolina Bays (Eyton&Parkhurst 7).
Ruling out meteoroids, the authors turn their attention to discussing the velocities and orbital characteristics of asteroids and comets.
The categorization of comets and asteroids are based upon differences in their material, orbital characteristics, and velocities. There is, however, considerable question as to how to classify each object upon entry to the earth’s atmosphere, "Sporadic meteoroids which can survive the atmospheric passage as stones or irons are probably fragments of asteroids, and fireballs, the remaining class, may be the nuclei of small comets" (Eyton & Parkhurst p.7). From the study of the velocities, orbital characteristics, known impact mechanisms (Baldwin 1963, The Measure of the Moon), and generalized Carolina Bay morphology, the authors were able to deduce that only a comet would possibly be responsible for bay creation. Prouty’s hypothesis regarding the cone shaped shock wave was utilized and expanded by the authors with their research. New data on the volatility of cometary material was also used in support of this hypothesis. Other support included the discussion of the Tunguska event; an event attributed to the explosion of a cometary nucleus over Siberia in 1908. The explosion from this event was heard from over 500 miles away from ground zero, leveled trees in a radial pattern for an approximately thirty mile radius away from ground zero (although trees directly at GZ were charred but left standing), and most importantly, created "shallow funnel shaped depressions no more than four or five meters in depth" (Eyton & Parkhurst 15).
The authors conclude by stating that their study had succeeded in showing that it was still possible that the bays were created from a comet, although in no way was their study definitive or conclusive. To reach a final consensus, the authors suggest studies that include: extensive dating of buried materials in bays to arrive at a consensus regarding their age, pollen analysis, soil profiling, wider regional geomorphology classification studies (based upon Thom’s method) to determine whether or not bays exist in only certain landscapes, and more research into the physics of cometary impacts.
The Carolina Bays: A Comparison With Modern Oriented Lakes
Raymond T. Kaczorowski, 1977
This study is considered the most comprehensive research ever done on the Carolina Bay issue. Kaczorowski literally traveled to the ends of the earth to conduct his study. In addition, he constructed elaborate models to test his hypothesis that Carolina Bays were the result of an "embarrassingly simple process" involving the mechanism outlined by Thom combined with wave and wind action (Kaczorowski, 120).
Before I begin discussion of Kaczorowski’s research, methods, models, and conclusions, I should point out that he begins his research upon the premise that terrestrial forces were responsible for bay development, and therefore disregards the validity of any hypothesis of extraterrestrial origin.
Kaczorowski begins his study by briefly describing bay characteristics, followed by a discussion of the meteoritic theory of Prouty. Unexplainably, Kaczorowski does not discuss the revised meteoritic theory, in which the causal mechanism is not the projectile, but the shock wave, and focuses on the older theory and the problems associated with Prouty’s magnetometer research. He shows that this theory is untenable on the basis that: the physics involved in an impact are unlikely to have created such shallow depressions, there are no known impact craters that resemble Carolina Bays on earth or elsewhere, no meteoritic material has ever been found that are associated with the bays, the bays are essentially a regional phenomenon restricted to the coastal plain, magnetic anomalies are probably due to anomalies within basement rocks (Kaczorowski 24-39). Apparently, Kaczorowski had no idea of the existence of the Eyton & Parkhurst paper or of Prouty’s modified meteoritic hypothesis.
With the criticism of extraterrestrial theories behind, Kaczorowski focuses on the theories of terrestrial creation and the progressive steps that led to the formulation of his hypothesis and research. After describing the pertinent points and problems of each study and hypothesis, Kaczorowski introduces us to his hypothesis; Carolina Bays owe their morphology to wave and wind action. To prove his point, Kaczorowski set up research missions to Northern Alaska, the Texas Panhandle, and to Southern Chile. Each of these areas has oriented lakes similar to Carolina Bays although they do differ greatly from the Atlantic coastal plain in climate, vegetation, and geology. Kaczorowski goes into great detail describing the physics behind the wave and wind action, which orient them.
A model, consisting of a trough of fine sand was constructed to replicate wind and wave action. Powerful fans were used to simulate wind conditions at the same angle as the prevailing winds of the Atlantic coastal plain. The findings were that, " A transition from an initial circular or irregular shape to an elliptical or near elliptical shape was observed in four to six hours" (Kaczorowski, 88).
In regards to the process that initially formed the bays, Kaczorowski conducted a survey of low altitude aerial photos, and determined that Carolina Bays have indeed formed on all geomorphic surfaces, contradicting the findings of Thom (Kaczorowski, 96). Kaczorowski instead suggests that the only requirement for bay existence is poor drainage leading to ponding mechanisms. He believes, as Thom did, that water table perching by an impervious layer of humate could have facilitated ponding.
In conclusion, Kaczorowski offers seven statements summarizing his research. As far as bay genesis, Kaczorowski offers this conclusion, "Although the development of these depressions is highly variable, absolutely no evidence has been encountered that would support an extraterrestrial origin" (Kaczorowski 119).
Twenty-two years have passed since Kaczorowski’s work was published, and there have not been any studies conducted which test his conclusions or comply with his suggestions for further research. Likewise, there have not been any serious studies into the validity of the Eyton & Parkhurst study. The door is still wide open for continued research into a set of truly interesting landforms. Based upon my research into pertinent literature, I have several suggestions for future research. Intensive field work is needed over a vast area of bay distribution to perform comparative analysis within several realms. First, a study of comparative bay age is a priority. Newly discovered dating methods may be the key this type of study. If the bays appear to be of roughly the same age, then one may attribute more validity to extraterrestrial theories of origin. If they have a wide age distribution, a terrestrial genesis is more likely. More intensive magnetometer studies may have similar results. Lastly, a comprehensive study of bay orientation would be a key factor in determining a causal mechanism. It is unlikely that wind and wave action would create similar orientations within such a vast area, especially since prevailing winds differ within the distribution area. It is now possible, using geographic information systems, to obtain a complete set of Carolina Bay data from the USGS DLG set. If there is a way to collect and isolate this data, there should be a means to obtain the long axis of each bay, calculate the azimuth of each axis, and perform statistical analysis on a regional or a complete scale. This would take years to accomplish, but given the right study, the mystery of the Carolina Bays may be one more step to being uncovered.