Devon Island Research Articles

An annotated checklist of the lichen biodiversity at two Mars analog sites: The Mars Desert Research Station (Utah, USA) and The Flashline Mars Arctic Research Station (Nunavut, Canada) recorded during the Mars 160 Mission

During the Mars 160 Mission in 2016 and 2017, crews at the Mars Desert Research Station (MDRS) in Utah, USA and the Flashline Mars Arctic Research Station (FMARS) on Tallurutit (Devon Island), Nunavut, Canada, conducted a collections‑based survey of lichen biodiversity at each of these Martian planetary analogs. Here we present the results of these studies as two annotated checklists, including 35 lichen spe‑ cies from MDRS and 13 species from FMARS, alongside details on the distribution of these species, relevant taxonomic notes, and photos of each species as an identification aid. This work adds to our knowledge of the biodiversity of these unique sites and provides an important baseline for future analog research at these stations.

Geomorphological and morphometric characterization of subglacial channels on Devon Island, Nunavut, Canada

Subglacial channels are morphologically and morphometrically distinct in comparison to fluvial channels, yet their identification from remote sensing data is still problematic. To contribute to the current set of criteria used to identify such channels, we performed a detailed analysis of two subglacial channel networks on Devon Island, Nunavut, Canada. In planform, these channels are isolated, finger-like networks that drain into a main stem and have distinct cross-sectional and longitudinal profiles. Cross-sections are flat-bottomed with steep walls and longitudinal profiles are convex and exhibit undulations, typical of pressurized water flow (i.e., subglacial flow). To facilitate remote sensing identification, we interrogated how well-known scaling relationships capturing hydraulics and mass balance dynamics of fluvial systems differ in subglacial channels. Scaling relationships typically used to discern connections between discharge and channel and catchment size in fluvial systems were applied to both networks, yielding trends distinct from the fluvial literature. We suggest that the weakly correlated relationship we found between channel discharge and the size of the drainage area indicates a discrete point or line source of water, such as a moulin or crevasse.

Modeling of the Impact‐Generated Hydrothermal System at the Haughton Impact Structure

AbstractHypervelocity impacts can generate hydrothermal systems, which have been suggested as candidate environments for prebiotic chemistry on the early Earth. The Haughton impact structure (a 23 km diameter crater located on Devon Island, Nunavut, Arctic Canada) displays evidence of water‐rock alteration indicative of a hydrothermal system generated from a cosmic impact. To model the formation of this crater and subsequent hydrothermal alteration, we have successfully developed a new two‐code methodology that utilizes a shock physics code and a hydrothermal code (HYDROTHERM). We can best reproduce the Haughton crater with a ∼700 m diameter projectile with an impact velocity of 14 km/s. With our approach, we were able to match all the major geological constraints observed at the Haughton impact structure. Our models show that the Haughton crater interior could have sustained temperatures ideal for thermophilic and hyperthermophilic life (50–120°C) for more than 50,000 years, indicating that these systems can sustain prebiotic chemistry and life for longer than previously estimated.

Glacial secrets uncovered: Revealing the modes of survival of metabolically active microbial communities entrapped in polar glacial ice

Glacial secrets uncovered: Revealing the modes of survival of metabolically active microbial communities entrapped in polar glacial ice

An Assessment of the Lancaster Sound Polynya Using Satellite Data 1979 to 2022

Situated between Devon Island and Baffin Island, Lancaster Sound is part of Tallurutiup Imanga, which is in the process of becoming the largest marine conservation area in Canada. The cultural and ecological significance of the region is due, in part, to a recurring polynya in Lancaster Sound. The polynya is demarcated by an ice arch that generally forms in mid-winter and collapses in late spring or early summer. Advanced Very High Resolution imagery from 1979 to 2022 was analyzed to determine the position, formation and collapse of the Lancaster Sound ice arch. The location of the ice arch demonstrates high interannual variability, with 512 km between the eastern and western extremes, resulting in a polynya area that can fluctuate between 6000 km2 and 40,000 km2. The timing of the seasonal ice arch formation and collapse has implications with respect to ice transport through Lancaster Sound and the navigability of the Northwest Passage. The date of both the formation and collapse of the ice arch is variable from season to season, with the formation observed between November and April and collapse usually occurring in June or July. A linear trend from 1979 to 2022 indicates that seasonal ice arch duration has declined from 150 to 102 days. The reduction in ice arch duration is a result of earlier collapse dates over the study period and later formation dates, particularly from 1979 to 2000. Lancaster Sound normally freezes west to east each season until the ice arch is established, but there is no statistical relationship between the ice arch location and duration. Satellite surface temperature mapping of the region indicates that the polynya is characterized by sub-resolution leads during winter.

Absorption and Scattering of UV and Visible Light Through Simulated Martian Regoliths and Rock Samples.

Ultraviolet shielding materials are potential ecological niches for biosignatures. Finding such materials on Mars would narrow the search for potentially habitable regions. A mini-goniometer was built to collect transmission spectra as a function of scattering angle for Mars analog regoliths (JSC Mars-1, basalt, cheto bentonite, and kieserite) and crystalline rock samples from the Haughton impact structure on Devon Island, Nunavut, in the Canadian High Arctic Archipelago. The transmission through the materials was assessed at ultraviolet and visible wavelengths and at different scattering angles. From the results, it is possible to classify the samples into UV transmitters and UV quenchers. UV transmitters are materials that favor transmittance of UV wavelengths compared to photosynthetically active radiation (PAR), while the UV quenchers are materials that effectively block UV radiation from propagating into the subsurface. Additionally, samples that are effective UV quenchers tend to have more isotropic scattering profiles, whereas UV transmitters tend to favor forward scattering profiles. Samples with greater porosity had greater overall transmission. The depths at which radioresistant microorganisms can exist on present-day Mars are estimated by modeling the transmission for regoliths and crystalline rocks under martian insolation. The depth at which LD90 occurs is found to range down to 0.3 mm, while still allowing up to 1000 kJ/m2 of PAR at those depths. Due to the exceptionally protective nature of JSC Mars-1, intimate mixtures of organisms and regolith will result in some organisms experiencing orders of magnitude less UV flux than others, even when protected by only a single grain of simulant.

Using Visual Observations to Compare the Behavior of Previously Immobilized and Non-Immobilized Wild Polar Bears

During 17 field seasons between 1973 and 1999, we conducted a long-term study of the behavior of undisturbed wild polar bears in Radstock Bay, southwest Devon Island, Nunavut. In a subset of 11 seasons (6 spring and 5 summer) between 1975 and 1997, we used three different drug combinations to chemically immobilize a small number of adult and subadult polar bears on an opportunistic basis and applied a temporary dye mark so that individual bears could be visually reidentified. We then used multinomial logistic regression to compare the behavior of 35 previously immobilized bears of five different demographic classes (sex, age, and reproductive status) to the behavior of non-immobilized bears of the same demographic classes in the same years and seasons. During the first two days after immobilization, bears slept significantly more and spent less time hunting than did bears that had not been immobilized. However, previously immobilized bears returned to the same behavioral patterns and proportion of total time spent hunting as non-immobilized bears within two days and no further negative behavioral effects were detected in the following 21 d. We visually confirmed successful hunting by three adult bears within 0.4 to 2.1 d of being immobilized, all of which went on to make additional kills within the following 24 h. The return to normal behavior patterns, including the ability to hunt successfully, within 48 h of immobilization appears consistent with the hypothesis that polar bears do not experience longer-term behavioral effects following brief chemical immobilization for conservation and management purposes.

Late Neoarchean terrane and Paleoproterozoic HT–UHT metamorphism on southern Devon Island, Canadian Arctic

The northernmost exposures of the Laurentian shield in Canada outcrop on Devon and Ellesmere islands, near the tectonic domains of the ≥2.6 Ga Rae Province and ca. 2.0–1.9 Ga Thelon–Inglefield orogenic arc. We report (Th)–U–Pb zircon and monazite ages along with phase equilibrium modelling pressure–temperature estimates for southern Devon Island, the only area on Devon or Ellesmere islands with previously known Archean rocks. Our results demonstrate that southern Devon Island is a late Neoarchean (ca. 2.55–2.47 Ga) terrane composed of lower to middle crustal, granulite facies rocks with evidence of anatexis and pervasive solid-state ductile deformation. Protoliths of clinopyroxene–garnet quartzofeldspathic gneiss, orthopyroxene quartzofeldspathic gneiss, two-pyroxene metabasite and biotite granite gneiss were emplaced between ca. 2.55–2.51 Ga, and a clastic sedimentary protolith for rutile–garnet metasedimentary rocks was deposited at ca. ≥2.47 Ga. Earlier, poorly constrained metamorphic events are recorded at ca. 2.54, 2.47 and 2.30 Ga, possibly associated with pulses of the Arrowsmith orogen (ca. 2.5–2.3 Ga). Most recently, this terrane was reworked by high temperature (HT) to ultrahigh temperature (UHT) metamorphism at ca. 1.91 Ga during with the Thelon–Inglefield orogen; obtaining peak P–T conditions of ca. 9 kbar and >850 °C. The discovery of a sapphirine–quartz metapelite assemblage is a first for the Canadian Arctic and is diagnostic evidence of UHT conditions within the Thelon-Inglefield orogenic zone.

Vessel risks to marine wildlife in the Tallurutiup Imanga National Marine Conservation Area and the eastern entrance to the Northwest Passage

The Arctic is changing rapidly due to climate change, which is allowing unprecedented levels of vessel traffic to transit the region. Vessel traffic can negatively affect marine wildlife in a number of ways, particularly in areas where vessels overlap with high concentrations of ecologically important species, and the significance of these impacts are of increased concern when the wildlife are also culturally important. Tallurutiup Imanga National Marine Conservation Area, located in Lancaster Sound, Nunavut, Canada, at the eastern entrance to the Northwest Passage, is experiencing the greatest levels of vessel traffic in the Canadian Arctic, and is important habitat for marine wildlife, including marine mammals and seabirds. Here, we examined the overlap between vessel traffic, including modeled underwater noise levels, and the distribution of two cetacean species, beluga and narwhal, and three seabird species, thick-billed murre, northern fulmar, and black-legged kittiwake. Narwhal had the highest vessel risk in Eclipse Sound and Milne Inlet, all three seabirds had high vessel risk at the eastern entrance to Eclipse Sound, with additional areas for northern fulmar at southern Devon Island and for black-legged kittiwake at Prince Leopold Island, and belugas had the highest vessel risk along southern and eastern Devon Island. Our results provide crucial information for implementing monitoring, conservation, and management initiatives for species inhabiting this protected area, and allow for a better understanding of the potential cultural implications of vessel-based marine wildlife impacts that will affect traditional subsistence hunting and local livelihoods.

Vermicular Ridge Features on Dundas Harbour, Devon Island, Nunavut

Conspicuous ridges with a circular, sinuous and anastomosing morphology, termed Vermicular Ridge Features (VRFs), have been observed along the coast of Dundas Harbour, Devon Island, Nunavut, Canada. Periglacial and glacial processes can produce morphologically similar ridge landforms, such as stone circles or ice disintegration features. However, VRFs are both morphologically and morphometrically distinct. We utilize aerial drone imagery, digital elevation models, grain size analysis, and field observations of VRFs to compare morphology, morphometry, environmental conditions and substrate characteristics to documented periglacial and glacial features with a circular to anastomosing ridge pattern. We interpret VRFs to be formed by paraglacial processes produced from the passive ablation of stagnant “dead” ice and subsequent deposition of supra- and englacial debris as a hummocky “ring-ridge” moraine. If these features are, in fact, ring-ridge moraines, then this is the first documentation of a ring-ridge moraine in Nunavut, Canada.

Marine Aerosol Records of Arctic Sea‐Ice and Polynya Variability From New Ellesmere and Devon Island Firn Cores, Nunavut, Canada

AbstractSea ice plays a critical role in the Earth’s climate system, including influencing ocean heat uptake, reflecting solar radiation, and contributing to dense water formation. Instrumental records of polar sea ice extent are only available since 1979, however. The short length of such records also limits our knowledge of polynya variability, which can reflect large‐scale atmospheric and climate changes. Ice core proxy records can extend these observations, but require further development and regional validation. We compare chloride and methanesulfonic acid concentrations from two new firn cores from the Canadian Arctic with satellite‐derived observations of regional sea‐ice concentration and polynya variability from 2002 to 2014. The sub‐annual resolution of these cores allows for detailed investigation of how regional sea‐ice concentration is recorded in the ice at Prince of Wales Icefield (POW), Ellesmere Island and Devon Ice Cap (DIC), Devon Island, Nunavut. Over the period 2002–2014 we find that the primary sources of marine aerosols to POW are polynyas within Arctic Canada and the Canada basin of the Arctic Ocean, whereas the primary sources of marine aerosols to DIC are a broader region of the Queen Elizabeth Islands, Baffin Bay, and the Arctic Ocean. Marine aerosol sources to the two core sites are distinct, reflecting different moisture source regions and, likely, differing transport pathways. Air mass back trajectory results support the satellite‐derived results. Glaciochemical records from this dynamic, warming region may provide a proxy for reconstructing North Water polynya and other regional polynya and shore‐lead variability prior to the satellite era.

Shell-bearing mollusks of the order Cephalaspidea (Gastropoda: Heterobranchia) of the Kara Sea: fauna and ecology

The survey of shell-bearing heterobranchs of the order Cephalaspidea of the Kara Sea has been done based on unpublished and literature data. The studied material includes that collected during expeditions aboard R/V Professor Multanovskiy in August–September 2019 and R/V Dalnie Zelentsy in August 2012. Additionally, the material of collections of the Zoological Institute of the Russian Academy of Sciences (Saint Petersburg) has been studied. The fauna of heterobranch molluscs of the order Cephalaspidea in the Kara Sea includes 18 described and 1 undescribed species that belong to 10 genera and 6 families. It has been specified that the type locality of Retusa semen Reeve, 1855 (Port Refuge) is located at Port Refuge National Historic Site of Canada, Devon Island, Nunavut, not in the Kara Sea. Retusa semen is considered here as species inquirenda because of the brief original description, significant differences in drawings of the shell of this species made by different authors, and the absence of type specimens. The presence of Diaphana minuta Brown, 1827, Laona quadrata (Wood, 1839), Philine sinuata Stimpson, 1851 and Retusa semen in the Kara Sea needs confirmation. Species numbers of heterobranch molluscs of the order Cephalaspidea decrease from the Barents Sea (21) through the Kara Sea (19) to the Laptev Sea (15) because of the decreasing proportion of boreal-arctic species. Among cephalaspids of the Kara Sea, the highest average abundance (individuals/m2) was observed for Cylichnoides densistriatus (Leche, 1878), and the highest average biomass for Cylichna corticata (Møller, 1842). The proportion of live individuals in the populations does not exceed 18% in late August – early September. The taxonomic structure of the cephalaspid fauna of the Kara Sea has been studied based exclusively on morphological characters. Further study of the fauna is needed based on molecular analyses of the material fixed in 96˚ alcohol.

Resolving the age of the Haughton impact structure using coupled 40Ar/39Ar and U-Pb geochronology

The Haughton Dome located on Devon Island, in the Canadian Archipelago represents a well-preserved, moderate-sized, complex impact crater. Previous age constraints for the 24 km-diameter impact structure have ranged from ca. 21 Ma to ca. 39 Ma. Herein, we present a coordinated microstructural and in situ U-Pb study of zircon and monazite coupled with 40Ar/39Ar laser step heating of shock-melted K-feldspar clasts from shock metamorphosed gneissic fragments collected from the allochthonous impact breccia at Haughton. Moderately shocked zircon and monazite grains yield an age distribution consistent with an Archean protolith metamorphosed at ca. 1.9 Ga, whereas shock recrystallized zircon and monazite yield a lower intercept age of 31.8 ± 1.7 Ma (n = 48, MSWD = 0.58, P = 0.99). Four inverse isochron 40Ar/39Ar ages of shocked feldspar clasts yield a weighted mean age of 31.04 ± 0.37 Ma (MSWD = 0.98, P = 0.40), within uncertainty of the U-Pb lower concordia intercept. Ar diffusion modelling supports the interpretation of the impact age and helps resolve impact-driven age resetting. These results highlight the power of coupling multiple geochronologic techniques for determining impact ages, especially from targets with complex geologic histories. Furthermore, they resolve previous discrepancies in the age of the Haughton Dome and the interpretation of the post impact stratigraphy of the crater fill.

Elemental composition, environment of deposition of the lower Carboniferous Emma Fiord formation oil shale in Arctic Canada

The sedimentary succession of 51-m consisting of a thin coal seam (1 m) and oil shale with a marlstone and carbonate-mudstone matrix of the Lower Carboniferous (Viséan) Emma Fiord Formation located on the Grinnell Peninsula, Devon Island, Arctic Canada was examined. The techniques used include reflected light microscopy, and instrumental neutron activation analysis (INAA) for elemental concentration, and inductively coupled plasma emission spectrometry (ICPES) for boron concentration.The coal and oil shale was deposited in a lacustrine, freshwater environment. Due to the climatic variation, two types of oil shale were developed based on the amount of precipitation. One with carbonate-mudstone matrix, with high calcite (75%) and low TOC (1.14–1.87%) content. The other a marlstone-dominated matrix with high aluminosilicate (64%) and TOC (16.4–53.6%) content.Oil shale from Emma Fiord experienced a slow rate of sedimentation and terrestrial flux as determined using Th/K/ Na/K, ratios Mn/Ca ratio to Ca respectively, and compared to the oil shale of Carboniferous age deposited in a lacustrine environment with a regular rate of recharge/discharge. The redox conditions for the Emma Fiord oil shale indicate anoxic to dysoxic conditions based on the variation of Cr and V + Ni.Thorium and U systematics indicate that U is more concentrated in oil shale with marlstone matrix and is associated with clay minerals and organic matter (OM), similar to the Carboniferous oil shale from the Big Marsh. The authigenic U is associated with TOC content and is higher for oil shale with the marlstone matrix.The variation of U with TOC indicates both paleo-productivity and preservation and is higher for oil shale with the marlstone matrix.The concentration of rare earth elements (REEs) is 95% due to the presence of light rare earth elements (LREEs) in both oil shale with marlstone and carbonate-mudstone matrices.The REES were normalized to the post-Archean average shale (PAAS). The high volatile bituminous coal at the base of the oil shale sections displays a flat, featureless pattern. The oil shale with a carbonate matrix decreases slightly from light rare earth elements (LREEs) to heavy rare earth elements (HREES). In contrast, the REEs concentration for oil shale with the marlstone matrix decreases more sharply from the LREEs (La-Eu) to HREEs (Tb-Lu). It displays a weak negative Eu anomaly typical of the upper continental crust.

An ∼1100 yr record of human and seabird occupation in the High Arctic inferred from pond sediments

Abstract Seabirds in the Canadian Arctic congregate in large colonies, producing oases of biological productivity and diversity in coastal regions. Here, we examined sterols, stanols, and stable isotopes (δ15N and δ13C) in three 14C-dated pond sediment cores near a large seabird colony and archaeological site on Devon Island (Nunavut, Canada), showing historical occupation by the seabirds and an ancient human (Thule or Norse) settlement over an ∼1100 yr time period. Coprostanol in the sediment records captures the presence of humans at ca. 1150 CE, followed by their abandonment of the site by ca. 1300 CE. Increased seabird presence at this site after ca.1200 CE is indicated by increases in δ15N and cholesterol/sitosterol. Seabird population expansion is observed after ca. 1600 CE in δ15N and cholesterol/sitosterol profiles, coinciding with European whaling activities that expanded in the seventeenth through nineteenth centuries. Our study provides insights into human and seabird occupation in the High Arctic to inform archaeological and conservation efforts.

P.354 Bloomed again: seasonality and clinical correlates in bipolar disorder

Important depositional characteristics indicative of climate change has been discovered in 50-m sedimentary succession consisting of oil shales with a marlstone and carbonate matrix of the Viséan shales from the Lower Carboniferous Emma Fiord Formation on Devon Island, Canada's Arctic Archipelago. Older Carboniferous (Tournaisian) shales, are however absent from Devon Island, but elsewhere such as Big Marsh, Nova Scotia, Tournaisian shales show no comparable evidence for climate change.The techniques used include reflected light microscopy, RockEval analyses, instrumental neutron activation analysis (INAA) for elemental concentration.Indeed, Viséan shales from the Lower part the Emma Fiord Formation from Devon Island have a marlstone matrix with abundant algal matter. The matrix also has low carbonate (32%) and total organic carbon (TOC) content between 33.3%and 55.6%. Moreover, the TOC show a positive correlation with authigenic uranium, and Mo, which suggests a high productivity due to the high rain, deeper water lacustrine depositional environment. Other Viséan oil shales from the Emma Fiord Formation on Devon Island have somewhat different characteristics from those with marlstone matrix. Indeed, they have a high (75%) carbonate content with calcified algal matter and low TOC (1.14–17.4%). A very low correlation between TOC and authigenic U, and Mo. Most importantly very high oil generation (98–413 L/t) potential of marlstones as compared to low yield of carbonate mudstones (4.1–17.0 L/t) shows a dramatic climatic shift to low precipitation and much dryer conditions. Such a drastic climatic condition has not been detected for the Tournaisian oil shales.

RADARSAT-2 Derived Glacier Velocities and Dynamic Discharge Estimates for the Canadian High Arctic: 2015–2020

RADARSAT-2 imagery collected each winter from 2015/2016 to 2019/2020 is used to quantify and characterize the variability in the motion of, and the discharge from, the major marine-terminating ice masses of the Queen Elizabeth Islands (QEI: Devon, Ellesmere and Axel Heiberg Islands) in the Canadian High Arctic. The majority of the glaciers did not experience significant variations in flow speeds over the observation period, and for most that did the variations are attributed to pulse and surge processes. However, there are exceptions where the velocity record indicates continued acceleration of the glaciers by processes that appear distinct from surging or pulsing, such as dynamic thinning. These include Trinity and Wykeham glaciers (Prince of Wales Icefield) and Belcher Glacier (Devon Ice Cap). The combination of surface velocities with ice thicknesses indicates that average ice discharge to the ocean for the QEI over the observation period was 2.78 ± 0.52 Gt a−1 (ranging between ∼2.37 ± 0.48 Gt a−1 and ∼3.20 ± 0.55 Gt a−1), ∼50% of which was channeled through the Trinity-Wykeham glacier basin alone. The results presented here, combined with those of previous studies, provide a comprehensive record of ice motion and discharge from the QEI between 2008 and 2020.

Robert McCormick and the circumstances of his Arctic fossil collection, 1852–1853

The Royal Navy surgeon Robert McCormick (1800–1890) took part in three mid-nineteenth century British Polar expeditions, two to the Arctic and one to the Antarctic. Of the two Arctic voyages, the first was to Spitsbergen (in today's Svalbard) in 1827; the second from 1852 to 1853, was one of the expeditions dispatched to search for the missing ships commanded by Sir John Franklin that had set out in 1845 to navigate a “Northwest Passage” through the islands of the Canadian Arctic. The Svalbard expedition was formative in developing McCormick's interest in the Polar regions, with the likely highlight of his career being his subsequent participation in the Antarctic expedition of 1839–1843 led by James Clark Ross. Throughout these expeditions, McCormick collected natural history specimens, principally in the fields of ornithology and geology. Many of the geological specimens he retained in a personal collection which passed to what is now the Natural History Museum, London, on his death in 1890. This collection includes rock specimens from Svalbard and Baffin Bay, and a substantial number of Silurian fossils (mostly brachiopods) from Beechey Island and Devon Island in the Canadian Arctic. The fossil collection was the largest of several assembled during the successive expeditions sent out in search of Franklin, but is one of those that has received no subsequent attention. That omission was largely due to McCormick's own scientific shortcomings and persisted despite his determined efforts to promote himself as a serious scientific naturalist and Arctic authority.

A novel geomatics method for assessing the Haughton impact structure

AbstractTerrestrial impact structures are typically modified by erosion, burial, and tectonic deformation. Their systematic morphologies are typically reconstructed through a combination of geological and topographic mapping, satellite imagery, and geophysical surveys. This study applies a novel geomatics approach to assessment of the morphology of the extensively studied Haughton impact structure (HIS), Devon Island, Nunavut, in order to test its potential to improve the accuracy and quality of future impact structure reconstruction. This new methodology integrates HIS lithological data, in the form of digitized geologic mapping, with a digital elevation model, within diametrically opposed, wedge‐shaped couplets, and plots these data as pseudo cross sections that capitalize on the radial symmetry of the impact structure. The pseudo cross sections provide an accurate reconstruction of the near‐surface stratigraphic sequences and terraces in the faulted annulus of the modified crater rim. The resultant pseudo cross sections support current interpretations regarding the 10–12 km diameter of the transient cavity, and successfully reproduce the visible outer ring and intermediate uplifted zone within the central basin. Observed positions of vertical offsets suggest that the extent of impact deformation extends beyond the current estimates of the apparent crater rim to radial distances of between 14 and 15 km. Finally, the new geomatics approach provides an improved determination of the spatial, stratigraphic, and temporal relationships among the Haughton Formation lake sediments, allochthonous crater‐fill impactites, and uplifted target rocks, and indicates that there was a not‐insignificant time gap between the formation of the impact structure and the deposition of the sediments.

Beach Freeze-up Investigations, Devon Island, Nunavut, Canada

Beach Freeze-up Investigations, Devon Island, Nunavut, Canada