Malcolm Lecompte

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Verified

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• Ph.D.
• Associate Pprofessor at Elizabeth City State University

We report diverse shock-metamorphosed and melted grains from the 1908 airburst site in Russia, one of history's most significant and enigmatic cosmic events. Analysis of samples from a rimmed crater-like feature near the epicenter using scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBS...

Sediment sequences spanning the 12,800-year-old lower Younger Dryas boundary (YDB) were investigated at three widely separated sites in eastern North America (Parsons Island, Maryland, a Newtonville sandpit in southern New Jersey, and Flamingo Bay, South Carolina). All sequences examined exhibit peak abundances in platinum (Pt), microspherules, and...

A previous study presented evidence supporting the hypothesis that a low-altitude airburst approximately 3600 years ago destroyed Tall el-Hammam, a Middle-Bronze-Age city northeast of the Dead Sea in modern-day Jordan. The evidence supporting this hypothesis includes a widespread charcoal-and-ash-rich terminal destruction layer containing shock-fra...

Asteroid and comet impacts can produce a wide range of effects, varying from large crater-forming events to high-altitude, non-destructive airbursts. Numerous studies have used computer hydrocode to model airbursts, primarily focusing on high-altitude events with limited surface effects. Few have modeled so-called “touch-down” events when an airbur...

Anomalous peak abundances of platinum and Fe-rich microspherules with high-temperature minerals have previously been demonstrated to be a chronostratigraphic marker for the lower Younger Dryas Boundary (YDB) dating to 12.8 ka. This study used Bayesian analyses to test this hypothesis in multiple sequences (units) of sandy, weakly stratified sedimen...

Many studies of hypervelocity impact craters have described the characteristics of quartz grains shock-metamorphosed at high pressures of > 10 GPa. In contrast, few studies have investigated shock metamorphism at lower shock pressures. In this study, we test the hypothesis that low-pressure shock metamorphism occurs in near-surface nuclear airburst...

Many studies of hypervelocity impact craters have described the characteristics of quartz grains shock-metamorphosed at high pressures of >10 GPa, but in contrast, few studies have investigated shock metamorphism at lower shock pressures. In this study, we test the hypothesis that low-pressure shock metamorphism occurs in near-surface nuclear airbu...

This study investigates the hypothesis that Earth collided with fragments of a disintegrating comet, triggering Younger Dryas climate change 12,800 years ago. This collision created environmental conditions at Abu Hureyra, Syria, that favored the earliest known continuous cultivation of domestic-type grains and legumes, along with animal management...

Many studies of hypervelocity impact craters have described the characteristics of quartz grains shock-metamorphosed at high pressures of >10 GPa. In contrast, few studies have investigated shock metamorphism at lower shock pressures. In this study, we test the hypothesis that low-pressure shock metamorphism occurs in near-surface nuclear airbursts...

At Abu Hureyra, a well-studied archeological site in Syria, the onset boundary of the Younger Dryas climatic episode ~12,800 years ago has previously been proposed to contain evidence supporting a near-surface cosmic airburst impact that generated temperatures >2000°C. Here, we present a wide range of potential impact-related proxies representing t...

A previous investigation revealed that shock-fracturing, a form of low-pressure shock metamorphism in quartz grains, can be produced during near-surface atomic airbursts and in cosmic impact structures, most likely at pressures lower than 8 GPa. This discovery implies that similar shock-fracturing may also form in quartz grains exposed to near-surf...

We present evidence that in ~ 1650 BCE (~ 3600 years ago), a cosmic airburst destroyed Tall el-Hammam, a Middle-Bronze-Age city in the southern Jordan Valley northeast of the Dead Sea. The proposed airburst was larger than the 1908 explosion over Tunguska, Russia, where a ~ 50-m-wide bolide detonated with ~ 1000× more energy than the Hiroshima atom...

At Abu Hureyra (AH), Syria, the 12,800-year-old Younger Dryas boundary layer (YDB) contains peak abundances in meltglass, nanodiamonds, microspherules, and charcoal. AH meltglass comprises 1.6 wt.% of bulk sediment, and crossed polarizers indicate that the meltglass is isotropic. High YDB concentrations of iridium, platinum, nickel, and cobalt sugg...

The Younger Dryas (YD) impact hypothesis proposes that fragments of a large, disintegrating asteroid/comet struck the Earth ∼12,800 years ago. This event simultaneously deposited high concentrations of platinum, high-temperature spherules, melt glass and nanodiamonds into the YD boundary layer (YDB) at >50 sites worldwide. Here, we report on a ∼12,...

Multi-proxy analyses of a sequence spanning the Younger Dryas (YD) in the Glacial Lake Hind basin of Manitoba provides insight into regional paleohydrology and paleovegetation of meltwater rivers and lakes spanning >4000 yr; the sequence is controlled by 25 new accelerator mass spectrometry ages. This lake, dammed by the Laurentide Ice Sheet, overf...

The Younger Dryas (YD) impact hypothesis posits that fragments of a large, disintegrating asteroid/comet struck North America, South America, Europe, and western Asia ~12,800 years ago. Multiple airbursts/impacts produced the YD boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds...

This paper overviews the multiple lines of evidence that collectively suggest a Tunguska-like, cosmic airburst event that obliterated civilization-including the Middle Bronze Age (MBA) city-state anchored by Tall el-Hammam-in the Middle Ghor (the 25 km diameter circular plain immediately north of the Dead Sea) ca. 1700 BCE, or 3700 years before pre...

The Younger Dryas cooling episode came about in the Northern Hemisphere in an abrupt manner atypical of deglaciation events. This cooling resulted in the Pleistocene extinctions of many genera of faunas and coincided with the disappearance of the Clovis culture. The Younger Dryas Cosmic Impact of 12.8 kya is then considered as a hypothesis that exp...

Chapter 8 reviews the evidence for a suspected cosmic impact over North America at the onset of the Younger Dryas climatic period with the near simultaneous extinction of classic Pleistocene megafauna and the Clovis technoculture. The impact related proxies that are used to detect the impact layer, such as spherules, silica-rich glass, nanodiamonds...

The Younger Dryas boundary (YDB) cosmic-impact hypothesis is based on considerable evidence that Earth collided with fragments of a disintegrating ≥100-km-diameter comet, the remnants of which persist within the inner solar system ∼12,800 y later. Evidence suggests that the YDB cosmic impact triggered an “impact winter” and the subsequent Younger D...

Part 1 of this study investigated evidence of biomass burning in global ice records, and here we continue to test the hypothesis that an impact event at the Younger Dryas boundary (YDB) caused an anomalously intense episode of biomass burning at ∼12.8 ka on a multicontinental scale (North and South America, Europe, and Asia). Quantitative analyses...

Previously, a large platinum (Pt) anomaly was reported in the Greenland ice sheet at the Younger Dryas boundary (YDB) (12,800 Cal B.P.). In order to evaluate its geographic extent, fire-assay and inductively coupled plasma mass spectrometry (FA and ICP-MS) elemental analyses were performed on 11 widely separated archaeological bulk sedimentary sequ...

Previous evidence for fragments of a cosmic airburst in the Western Alps has been shown to reside in weathering rinds in surface clasts of Late Glacial (LG) (mid-LG-post Allerød) deposits and in Ah horizons of several associated paleosols. In contrast to outlying strata, Younger Dryas (YD) paleosol horizons contain minor reworked airburst evidence...

Holliday (1) rejects age-depth models for the Younger Dryas boundary layer (YDB) in Kennett et al. (2), claiming that they are incorrect for several reasons, including age reversals, high age uncertainties, and use of optically stimulated luminescence (OSL) dating. These same claims previously were presented in Meltzer et al. (3) and were discussed...

Significance A cosmic impact event at ∼12,800 Cal B.P. formed the Younger Dryas boundary (YDB) layer, containing peak abundances in multiple, high-temperature, impact-related proxies, including spherules, melt glass, and nanodiamonds. Bayesian statistical analyses of 354 dates from 23 sedimentary sequences over four continents established a modeled...

A sediment column (0-110 cm) from Squires Ridge (38ED365), a stratified archaeological site on the Tar River in North Carolina, was analyzed to evaluate magnetic microspherules and other geochemical markers reported for the Younger Dryas Boundary (YDB). Here we report on microspherules using a Scanning Electron Microscope (SEM) and Energy Dispersiv...

The presence of Mn-Fe nodules in the epipedons (surface horizons) of paleosols of presumed Upper Neogene age in the northwestern Venezuelan Andes have been interpreted as products of inorganic oxidation and reduction processes operating over the full range of glacial and interglacial cycles that affected paleosol morphogenesis. New microscopic/chem...

Significance This study ties the spherules recovered in Pennsylvania and New Jersey to an impact in Quebec about 12,900 y ago at the onset of Younger Dryas. Our discovery resulted from an exhaustive search that examined the question of whether there is any evidence of extraterrestrial platinum group metals present in the bulk sediments, magnetic gr...

Gradual reduction of a small ice shelf in the Pine Island Bay area is measured using eleven Landsat images spanning 1972 to 2003. Measurements of Ice shelf area indicate that it expanded slightly during the first two decades of observations from approximately 6.19 km 2 measured on December 7, 1972 to a maximum of about 6.82 km2 observed in 1986. Th...

In PNAS, M. Boslough (1) raises issues about carbon spherules and nanodiamonds unrelated to our magnetic spherule focused research (2). Boslough should instead address the questions he raises to the appropriate investigators.

Firestone et al. sampled sedimentary sequences at many sites across North America, Europe, and Asia [Firestone RB, et al. (2007) Proc Natl Acad Sci USA 106:16016-16021]. In sediments dated to the Younger Dryas onset or Boundary (YDB) approximately 12,900 calendar years ago, Firestone et al. reported discovery of markers, including nanodiamonds, aci...

This study examines the feasibility of human exploration of near-Earth asteroids before 2030. Missions are assumed possible with the development of upgraded expendable launch vehicles and a spacecraft similar to the Constellation Program's Orion crew exploration vehicle. Candidate objects and opportunities were determined by filtering a Jet Propuls...

Evidence for the harsh climate prevalent during the Last Glacial Maximum (LGM) are seen in topographical features visible south of the ice sheet margin in the uplands and coastal regions of the southeastern United States. Among the features attributed to ice age climate are numerous elliptical, shallow depressions called collectively Carolina Bays,...

Watershed Watch (NSF-DUE-STEP 0525433) engages early undergraduate students from two-year and four-year colleges in student-driven full inquiry-based instruction in biogeoscience. Program goals for Watershed Watch are to test if inquiry-rich student-driven projects sufficiently engage undeclared students (or noncommittal STEM majors) to declare a S...

Firestone and others proposed an extraterrestrial (ET) impact upon the Laurentide Ice Sheet 12,900 years ago led to abrupt climate change and left behind a distinct suite of microscopic soil markers. If so, then soil memory of such an extreme event should be apparent across a wide swath of ice-marginal North America. New Jersey's Pine Barrens has a...

With the nation challenged to comply with Executive Order 12906 and its needs to augment the Science, Technology, Engineering and Mathematics (STEM) pipeline, applied focus on geosciences pipelines issue may be at risk. The Geosciences pipeline may require intentional K-12 standard course of study consideration in the form of project based, science...

Stratigraphic analyses of soil samples taken from dated and undated sites located along the mid-Atlantic Coastal Plain have yielded evidence of increased contemporary biomass burning, compared to under and overlying strata. Host strata ages are known or projected to bracket the onset of the Younger Dryas cooling episode at 12.9 cal ka. This ongoing...

Despite increases over the last two decades in the degrees awarded to underrepresented students in science, technology, engineering, and mathematics (STEM) disciplines, enhancing diversity in these disciplines remains a significant challenge. This paper describes a strategic approach to this challenge via the development of a collaborative partners...

Development of the Ares launch system and Orion Crew Exploration Vehicle open up a number of possible opportunities in the inner solar system for human exploration. Of particular interest in this regard are near-Earth objects (NEOs).

Detection of archaeological sites may be accomplished by several means including visual aerial reconnaissance and the me of remote sensors as aerial cameras, thermal infrared scanners, multispectral scanners, and space-borne radar. Remote sensing has proven to be useful in locating both surface and subsurface archaeological features. Much of human...

Imaging the earth from Geostationary Earth Orbit (GEO) allows frequent updates of environmental conditions within an observable hemisphere at time and spatial scales appropriate to the most transient observable terrestrial phenomena. Coverage provided by current GEO Meteorological Satellites (METSATS) fails to fully exploit this advantage due prima...

Earth Imaging from Geostationary Earth Orbit (GEO) allows frequent sampling of the environment within an observable hemisphere. GEO Meteorological Satellites, have exploited this advantage for over three decades. Visual imaging from these satellites could be characterized as low in spatial and temporal resolution. The absence of ‘true color’, and h...

The passive multispectral IR polarization signature attributes of mines and background are observable to an appropriately designed detection system. The processes that create signature polarization are spectrally dependent. At shorter wavelengths, reflected solar radiation produces polarization which is perpendicular to the plane of incidence. At l...

Different Mars mission designs recently proposed are examined to illustrate the principal features of possible chemical rocket propellants from native resources on the Martian surface. A simple analytic tool developed to compare different mission approaches including the impact of in situ propellant production is examined. Quantitative criteria to...

Limb profiles obtained by the Pioneer Venus orbiter ultraviolet spectrometer (PVOUVS) are analyzed. The analysis is confined to those data obtained when the spacecraft was near periapsis (∼150‐200 km altitude) and the PVOUVS grating is set to a center‐of‐band‐pass wavelength of 297 nm. Sources are identified which give rise to the observed signal a...

The ultraviolet nitric oxide spectrometer (UVNO) experiment on the Atmosphere Explorer D (AE-D) satellite measured thermospheric nitric oxide during the winter of 1974-1975 using resonant fluorescence from the 1-0 gamma band of the molecule. Almost complete latitude coverage was obtained, but the observations were confined to morning local times cl...

Recent analyses of the Atmosphere Explorer data are discussed in which it is demonstrated that the satellite glows have two components, one at high altitudes which is consistent with excitation in single collisions of atmospheric oxygen atoms with the vehicle surface and the other at low altitudes which is consistent with double collisions of nitro...

Earth Imaging from Geostationary Earth Orbit (GEO) allows frequent sampling of the environment within an observable hemisphere. GEO Meteorological Satellites, have exploited this advantage for over three decades. Visual imaging from these satellites could be characterized as low in spatial and temporal resolution. The absence of 'true color', and h...

The wind-driven seaward movement of warm coastal surface water and its associated displacement by cold bottom water describes the oceanic process of coastal upwelling. As cold deep water rises to the surface, vital nutrients necessary to sustain abundant and varied sea life are replenished. Although marine ecosystems may be periodically enriched du...