The Carolina Bays are conic sections

[citpeks]

The impact origin of the Carolina Bays is described in Chapter 27 of Graham Hancock's new book "America Before". Hancock references the peer-reviewed publication in Geomorphology[1] and describes the antagonism with which new ideas are received by the scientific establishment, which is reminiscent of an old ATM thread:

[1] Zamora, A., A model for the geomorphology of the Carolina Bays, Geomorphology (2017), DOI 10.1016/j.geomorph.2017.01.019 https://dx.doi.org/10.1016/j.geomorph.2017.01.019

book-cover.jpg
GIIH-Hancock.jpg

[Roger E. Moore]

I went to the SAO/NASA Astrophysics Data System at http://cdsads.u-strasbg.fr/ and used the keywords Carolina bays impact 2000-2019. About a third to a half of the 52 papers resulting concern the possibility that the "Carolina Bays" in part or whole are the result of a Younger Dryas impact event. This Younger Dryas event is one of the "mysteries" in the thread posted in the Astronomy forum.

Reading the relevant papers, I get the impression that the jury is still out, but most researchers have turned away from the impact hypothesis to other explanations. Not enough work (this is my guess) has been done on the topic to say definitively one way or the other.

The Younger Dryas impact does appear to have occurred: https://forum.cosmoquest.org/showthr...61#post2467061 (Greenland astrobleme).

However, the issue here is the true connection (or lack thereof) of the Carolina Bays to that or another impact.

[Roger E. Moore]

More on the Greenland impact(s):

http://cdsads.u-strasbg.fr/abs/2018AGUFMPP41B..01M

A large impact crater beneath the ice in northwest Greenland
Authors: MacGregor, J. A., et al. (many authors)
Publication: American Geophysical Union, Fall Meeting 2018, abstract #PP41B-01
Publication Date: 12/2018

A rarely considered element of Arctic system change in the Pleistocene is the possibility and consequences of any large high-latitude impact. We report the discovery of a large impact crater hidden beneath Hiawatha Glacier in northwest Greenland. From airborne radar surveys, we identify a 31-kilometer-wide, circular bedrock depression beneath up to a kilometer of ice. This depression has an elevated rim that cross-cuts tributary subglacial channels and a subdued central uplift that appears to be actively eroding. From ground investigations of the deglaciated foreland, we identify overprinted structures within Precambrian bedrock along the ice margin that strike tangent to the subglacial rim. Glaciofluvial sediment from the largest river draining the crater contains shocked quartz and other impact-related grains. Geochemical analysis of this sediment indicates that the impactor was a fractionated iron asteroid, which must have been more than a kilometer wide to produce the identified crater. Radiostratigraphy of the ice in the crater shows that the Holocene ice is continuous and conformable, but all deeper and older ice appears to be debris-rich or heavily disturbed. The age of this impact crater is presently unknown, but from our geological and geophysical evidence, we conclude that it is unlikely to predate the Pleistocene inception of the Greenland Ice Sheet.

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http://cdsads.u-strasbg.fr/abs/2019LPI....50.1318K

An Independent Discovery of Subglacial Impact Crater in Northwest Greenland by Gravity Aspects from Earth Gravity Model EIGEN 6C4 and Magnetic Anomaly Data
Kletetschka, G.; Klokocník, J.; Kostelecký, J.; Bezdek, A.; Cílek, V.
Publication: 50th Lunar and Planetary Science Conference, held 18-22 March, 2019 at The Woodlands, Texas. LPI Contribution No. 2132, id.1318
Publication Date: 03/2019

We independently support the recent discovery of a large impact crater beneath Hiawatha Glacier in northwest Greenland with the gravity and magnetic data.

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http://cdsads.u-strasbg.fr/abs/2019GeoRL..46.1496M

A Possible Second Large Subglacial Impact Crater in Northwest Greenland
Authors: MacGregor, Joseph A.; et al. (many authors)
Publication: Geophysical Research Letters, Volume 46, Issue 3, pp. 1496-1504 (GeoRL Homepage)
Publication Date: 02/2019

Following the discovery of the Hiawatha impact crater beneath the northwest margin of the Greenland Ice Sheet, we explored satellite and aerogeophysical data in search of additional such craters. Here we report the discovery of a possible second subglacial impact crater that is 36.5-km wide and 183 km southeast of the Hiawatha impact crater. Although buried by 2 km of ice, the structure's rim induces a conspicuously circular surface expression, it possesses a central uplift, and it causes a negative gravity anomaly. The existence of two closely spaced and similarly sized complex craters raises the possibility that they formed during related impact events. However, the second structure's morphology is shallower, its overlying ice is conformal and older, and such an event can be explained by chance. We conclude that the identified structure is very likely an impact crater, but it is unlikely to be a twin of the Hiawatha impact crater.

[Strange]

The impact origin of the Carolina Bays is described in Chapter 27 of Graham Hancock's new book "America Before". Hancock references the peer-reviewed publication in Geomorphology[1] and describes the antagonism with which new ideas are received by the scientific establishment, which is reminiscent of an old ATM thread:

[1] Zamora, A., A model for the geomorphology of the Carolina Bays, Geomorphology (2017), DOI 10.1016/j.geomorph.2017.01.019 https://dx.doi.org/10.1016/j.geomorph.2017.01.019

Just to be clear, that is your own paper?

And of course (most) new ideas are met with antagonism. That is a Good Thing. It is what makes the scientific process so effective.

[Roger E. Moore]

Despite the "Carolina bays come from an impact" question being declared resolved in 2011, the debate is a lively one today. A few people in particular are keeping the discussion alive.

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http://cdsads.u-strasbg.fr/abs/2011ESRv..106..247P

The Younger Dryas impact hypothesis: A requiem
Pinter, Nicholas; Scott, Andrew C.; Daulton, Tyrone L.; Podoll, Andrew; Koeberl, Christian; Anderson, R. Scott; Ishman, Scott E.
Earth Science Reviews, Volume 106, Issue 3, p. 247-264. (06/2011)

The Younger Dryas (YD) impact hypothesis is a recent theory that suggests that a cometary or meteoritic body or bodies hit and/or exploded over North America 12,900 years ago, causing the YD climate episode, extinction of Pleistocene megafauna, demise of the Clovis archeological culture, and a range of other effects. Since gaining widespread attention in 2007, substantial research has focused on testing the 12 main signatures presented as evidence of a catastrophic extraterrestrial event 12,900 years ago. Here we present a review of the impact hypothesis, including its evolution and current variants, and of efforts to test and corroborate the hypothesis. The physical evidence interpreted as signatures of an impact event can be separated into two groups. The first group consists of evidence that has been largely rejected by the scientific community and is no longer in widespread discussion, including: particle tracks in archeological chert; magnetic nodules in Pleistocene bones; impact origin of the Carolina Bays; and elevated concentrations of radioactivity, iridium, and fullerenes enriched in 3He. The second group consists of evidence that has been active in recent research and discussions: carbon spheres and elongates, magnetic grains and magnetic spherules, byproducts of catastrophic wildfire, and nanodiamonds. Over time, however, these signatures have also seen contrary evidence rather than support. Recent studies have shown that carbon spheres and elongates do not represent extraterrestrial carbon nor impact-induced megafires, but are indistinguishable from fungal sclerotia and arthropod fecal material that are a small but common component of many terrestrial deposits. Magnetic grains and spherules are heterogeneously distributed in sediments, but reported measurements of unique peaks in concentrations at the YD onset have yet to be reproduced. The magnetic grains are certainly just iron-rich detrital grains, whereas reported YD magnetic spherules are consistent with the diffuse, non-catastrophic input of micrometeorite ablation fallout, probably augmented by anthropogenic and other terrestrial spherular grains. Results here also show considerable subjectivity in the reported sampling methods that may explain the purported YD spherule concentration peaks. Fire is a pervasive earth-surface process, and reanalyses of the original YD sites and of coeval records show episodic fire on the landscape through the latest Pleistocene, with no unique fire event at the onset of the YD. Lastly, with YD impact proponents increasingly retreating to nanodiamonds (cubic, hexagonal [lonsdaleite], and the proposed n-diamond) as evidence of impact, those data have been called into question. The presence of lonsdaleite was reported as proof of impact-related shock processes, but the evidence presented was inconsistent with lonsdaleite and consistent instead with polycrystalline aggregates of graphene and graphane mixtures that are ubiquitous in carbon forms isolated from sediments ranging from modern to pre-YD age. Important questions remain regarding the origins and distribution of other diamond forms (e.g., cubic nanodiamonds). In summary, none of the original YD impact signatures have been subsequently corroborated by independent tests. Of the 12 original lines of evidence, seven have so far proven to be non-reproducible. The remaining signatures instead seem to represent either (1) non-catastrophic mechanisms, and/or (2) terrestrial rather than extraterrestrial or impact-related sources. In all of these cases, sparse but ubiquitous materials seem to have been misreported and misinterpreted as singular peaks at the onset of the YD. Throughout the arc of this hypothesis, recognized and expected impact markers were not found, leading to proposed YD impactors and impact processes that were novel, self-contradictory, rapidly changing, and sometimes defying the laws of physics. The YD impact hypothesis provides a cautionary tale for researchers, the scientific community, the press, and the broader public.

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http://cdsads.u-strasbg.fr/abs/2012QuRes..77..171R

Burning peat and reworking loess contribute to the formation and evolution of a large Carolina-bay basin
Rodriguez, Antonio B.; Waters, Matthew N.; Piehler, Michael F.
Quaternary Research, Volume 77, Issue 1, p. 171-181. (01/2012)

Carolina bays are nearly ubiquitous along ~ 1300 km of the North American Atlantic Coastal Plain, but relatively few bays have been examined in detail, making their formation and evolution a topic of controversy. The Lake Mattamuskeet basin, eastern North Carolina, USA, is a conglomeration of multiple Carolina bays that form a > 162 km2 lake. The eastern shoreline of the lake is made up of a 2.9-km-wide plain of parabolic ridges that recorded rapid shoreface progradation. The lower shoreface deposit contains abundant charcoal beds and laminae dated 6465-6863 cal yr BP, corresponding with initiation of a lacustrine environment in the eastern part of the lake. A core from the western part of the lake sampled a 1541-1633 cal yr BP charcoal bed at the base of the lacustrine unit, indicating formation of this part of the basin postdates the eastern basin. Lake Mattamuskeet has no relationship to the Younger Dryas or a linked impact event because rim accretion significantly postdates 12,000 cal yr BP. The shoreline progradation, and association of charcoal beds with the oldest lake sediment in both main parts of the basin, suggest that fire and subsequent hydrodynamic processes were associated with initial formation of these Carolina bays.

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http://cdsads.u-strasbg.fr/abs/2015AGUFMED31C0906H

Citizen Science and the Unsolved Austral-Asian Tektite Mystery
Harris, T. H. S.; Davias, M. E.
American Geophysical Union, Fall Meeting 2015, abstract id. ED31C-0906 (12/2015)

A growing body of mid-Pleistocene evidence suggests a 786 ka cosmic impact (MIS 20) at an oblique angle onto the North American ice sheet may have created both the Carolina Bays on the US Eastern coastal plane, as well as the 60 billion tons of Australasian (AA) tektites that cover ¼ to 1/3 of Earth. No AA impact structure has ever been identified. ~12 ka after the AA tektite event came the Brunhes-Matuyama geomagnetic reversal, Earth's most recent. In 1986, Richard Muller's paper "Geomagnetic Reversals from Impacts on the Earth" explained how a geologically rapid change of Earth's crustal spin rate relative to the liquid core would upset its convective cellular dynamo structure, disrupting and dismantling Earth's magnetic field. Muller proposed an impact-induced mini ice age to transport 10 meters of low- and mid-latitude sea into ice at the poles, changing the crustal polar moment of inertia and accelerating rotation relative to the core. Muller's impact ice age is a weak point, but oblique cosmic impacts deliver tangential impulse directly. The Carolina Bays are a depositional formation of high purity quartz sand, angular to subangular in grain texture, covering approximately 5% of the continental US, with an estimated volume of 1600 km3 over the east coastal plain and some of Nebraska. The bays themselves are depressions in the sand layer, expressed through depositional overburden. They range from a few hundred meters to several kilometers in scale. Carolina Bays are now characterized with LiDAR altimetry. Their alignment is systematic by latitude. They conform to 6 archetype ovoid shapes, easily derived using suborbital mechanics. This implies suborbital mechanics was a governor of their transport: the imprint is a snapshot of the emplacement process. Suborbital Analysis using co-aligned axes of 45,000 Carolina Bays indicates the ice sheet impact region was the Georgian Bay, across Lake Huron to Michigan's Saginaw Bay. The average downrange distance of the sand equates to an imparted velocity and a linear impulse per the mass of the sand. This linear impulse applied over Earth's radius gives a |Deltaomega| the same order Muller predicted would be necessary, 0.03 cm/s at the core mantle boundary. If the AA tektite impact was oblique, what other imprinted signatures may remain detectable, and where?

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http://cdsads.u-strasbg.fr/abs/2017Geomo.282..209Z

A model for the geomorphology of the Carolina Bays
Zamora, Antonio
Geomorphology, Volume 282, p. 209-216. (04/2017)

Geometrical analysis of the Carolina Bays using Google Earth in combination with LiDAR data makes it possible to postulate that the bays formed as the result of impacts, rather than from eolian and lacustrine processes. The Carolina Bays are elliptical conic sections with width-to-length ratios averaging 0.58 that are radially oriented toward the Great Lakes region. The radial distribution of ejecta is one characteristic of impacts, and the width-to-length ratios of the ellipses correspond to cones inclined at approximately 35°, which is consistent with ballistic trajectories from the point of convergence. These observations, and the fact that these geomorphological features occur only on unconsolidated soil close to the water table, make it plausible to propose that the Carolina Bays are the remodeled remains of oblique conical craters formed on ground liquefied by the seismic shock waves of secondary impacts of glacier ice boulders ejected by an extraterrestrial impact on the Laurentide Ice Sheet. Mathematical analysis using ballistic equations and scaling laws relating yield energy to crater size provide clues about the magnitude of the extraterrestrial event. An experimental model elucidates the remodeling mechanisms and provides an explanation for the morphology and the diverse dates of the bays.

(see two references below)

[Roger E. Moore]

Last two references:

http://cdsads.u-strasbg.fr/abs/2017AGUFM.P11A2496H

Correlating Distal, Medial and Proximal Ejecta Transport/Emplacement From Oblique Cosmic Impact On North American Continental Ice Sheet At MIS20 (786 ka) Via Suborbital Analysis (SA)
Harris, T. H. S.; Davais, M. E.
American Geophysical Union, Fall Meeting 2017, abstract #P11A-2496 (12/2017)

Several elements of the 786 ka Australasian (AA) tektite imprint bear close scrutinyin order to locate the parent impact site or structure. The unique Carolina bays unit geologic formation is indicated as a large "medial" ejecta blanket from a large cosmic impact during a period containing 786 ka. Coincidence? Kg-scale sub-spherical hollow splash form AA tektites implies prolonged atmospheric blow out-scale momentum current with a core of sub-parallel or divergent flow volume having essentially zero turbulence. This would allow for plasma entrainment and heating of target mass at prolonged low dynamic pressure during outflow, where adiabatic expansion could deliver both semi-solid Muong Nong-type and inviscid melts above the atmosphere for gentle release upon rarefaction in vacuum. Within a large atmospheric blow-out scale momentum current, target mass becomes entrained at the speed of adiabatic outflow. 10+ km/s ejecta entrainment yields inter-hemispheric emplacement from launch per governing suborbital mechanics, without question. Oblique impact into a thick ice sheet explains reduced excavation volume and shearing disruption in the form of hypersonic steam plasma scouring. Adiabatic expansion would be immediately available to accelerate and further heat proto-tektite target mass. With shock no longer the sole transport engine, kg-scale splash forms and tektite speeds above the post-shock vaporization velocity of quartz are explained by expansion of shocked ice, in agreement with the observed imprint. The 6 Carolina bay shapes or "Davias Archetypes" are reproducible using conic perturbation in Suborbital Analysis, conforming to a formative mechanism of suborbital transport and ballistic emplacement: "Suborbital Obstruction Shadowing" needs only 3 parts in 10,000 of VEL variation around a circular EL-AZ-VEL launch cone, before considering re-entry effects. Transport energy of the Carolina bay sand, calculated using the 3.5 to 4 km/s launch VEL required for its indicated transport, must account for inefficiency of entrained transport. Roughly 1600 cubic kilometers of Carolina bays sand must have taken 10 to 1000 times more energy to transport than the entire Chixulub event yield. Imagery by M. E. Davias of Cintos.org, S.E. Nebraska (top) and Bennettsville, South Carolina (bottom).

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http://cdsads.u-strasbg.fr/abs/2017AGUFM.P11A2499D

Imaging 50,000 Oriented Ovoid Depressions Using LiDAR Elevation Data Elucidates the Enigmatic Character of The Carolina Bays: Wind & Wave, Or Cosmic Impact Detritus?
Davias, M. E.; Harris, T. H. S.
American Geophysical Union, Fall Meeting 2017, abstract #P11A-2499 (12/2017)

80 years after aerial photography revealed thousands of aligned oval depressions on the USA's Atlantic Coastal Plain, the geomorphology of the "Carolina bays" remains enigmatic. Geologists and astronomers alike hold that invoking a cosmic impact for their genesis is indefensible. Rather, the bays are commonly attributed to gradualistic fluvial, marine and/or aeolian processes operating during the Pleistocene era. The major axis orientations of Carolina bays are noted for varying statistically by latitude, suggesting that, should there be any merit to a cosmic hypothesis, a highly accurate triangulation network and suborbital analysis would yield a locus and allow for identification of a putative impact site. Digital elevation maps using LiDAR technology offer the precision necessary to measure their exquisitely-carved circumferential rims and orientations reliably. To support a comprehensive geospatial survey of Carolina bay landforms (Survey) we generated about a million km2 of false-color hsv-shaded bare-earth topographic maps as KML-JPEG tile sets for visualization on virtual globes. Considering the evidence contained in the Survey, we maintain that interdisciplinary research into a possible cosmic origin should be encouraged. Consensus opinion does hold a cosmic impact accountable for an enigmatic Pleistocene event - the Australasian tektite strewn field - despite the failure of a 60-year search to locate the causal astroblem. Ironically, a cosmic link to the Carolina bays is considered soundly falsified by the identical lack of a causal impact structure. Our conjecture suggests both these events are coeval with a cosmic impact into the Great Lakes area during the Mid-Pleistocene Transition, at 786 ka ± 5 k. All Survey data and imagery produced for the Survey are available on the Internet to support independent research. A table of metrics for 50,000 bays examined for the Survey is available from an on-line Google Fusion Table: https://goo.gl/XTHKC4 . Each bay is also geospatially referenceable through a map containing clickable placemarks that provide information windows displaying that bay's measurements as well as further links which allows visualization of the associated LiDAR imagery and the bay's planform measurement overlay within the Google Earth virtual globe: https://goo.gl/EHR4Lf .

[Roger E. Moore]

It sounds like the discussion on an impact original for the Carolina bays has shifted from the bays being the impact structures themselves to the bays being secondary impacts from debris from the original impact(s).

[PetersCreek]

[...]which is reminiscent of an old ATM thread:

citpeks,

You have linked to your ATM more than once in this thread. Please don't do it again. That thread is closed. You may not promote, argue, or attempt to support it outside of the ATM forum. If you want to revisit that topic, report the closing post in the ATM thread and state your case for reopening it.

[citpeks]

citpeks,

You have linked to your ATM more than once in this thread. Please don't do it again. That thread is closed. You may not promote, argue, or attempt to support it outside of the ATM forum. If you want to revisit that topic, report the closing post in the ATM thread and state your case for reopening it.

I apologize. I did not know that there was a rule against referencing a previous thread.

[Reality Check]

The impact origin of the Carolina Bays is described in Chapter 27 of Graham Hancock's new book "America Before"...

Interesting book but not scientific literature or even new research, citpeks. What you say about Hancock's opinion makes it close to wrong - new scientific ideas are supposed to be received with "antagonism". Any new scientific theory is questioned and needs defending. The impact origin theory was no different.

A model for the geomorphology of the Carolina Bays by Antonio Zamora does not seem to cover much new ground. This is a geometrical analysis that does not rule out the postulate that the bays formed as the result of impacts from a comet impact on or above the Laurentide ice sheet about 12,900 years ago. A small issue is the author is not a geologist or astronomer. Antonio Zamora is a computer consultant with a couple of book about the bays so he does have some knowledge about them. That 2017 paper is his first paper on the bays.

This impact postulate (a comet impact on or above the Laurentide ice sheet about 12,900 years ago) is discredited by the dating of the bays. Carolina bay - Impact event

The cometary impact hypothesis of the origin of the bays was popular among earth scientists of the 1940s and 50s. After considerable debate and research, geologists determined the depressions were both too shallow and lacking in any evidence for them to be impact features. Reports of magnetic anomalies turned out not to show consistency across the sites. There were no meteorite fragments, shatter cones or planar deformation features. None of the necessary evidence for hypervelocity impacts was found. The conclusion was to reject the hypothesis that the Carolina Bays were created by impacts of asteroids or comets (Rajmon 2009).

A new type of extraterrestrial impact hypothesis was proposed as the result of interest by both popular writers and professional geologists in the possibility of terminal Pleistocene extraterrestrial impacts, including the Younger Dryas impact hypothesis. However, the idea that the Carolina bays were created by a low density comet exploding above or impacting on the Laurentide ice sheet about 12,900 years ago has been discredited by OSL dating of the rims of the Carolina bays, paleoenvironmental records obtained from cores of Carolina bay sediments, and other research that shows that many of them are as old as, or older than, 60,000 to 140,000 BP.[16][17][18][33][34]

Those dates come from sources published between 1996 and 2015. This impact postulate has been wrong for at least 4 years. Antonio Zamora does not mention this in his abstract.

[Swift]

The most recent discussion has been moved to this thread in ATM.