Using in situ cosmogenic 10Be, 14C, and 26Al to decipher the history of polythermal ice sheets on Baffin Island, Arctic Canada

Southeasternmost Baffin Island is mantled by Hudson Strait drift; it contains abundant limestone erratics and 20 to 50% carbonate in the matrix. To the northwest, it is replaced by drift dominated by locally derived rock of the Canadian Shield. The sense and orientation of ice-erosional features demonstrate that Hudson Strait drift is associated with northeasterly ice flow that crossed the tip of Meta Incognita Peninsula; local drift, associated with ice flow S10°W along the Hudson Strait coast, was derived from a dispersal center on the peninsula. Erratic lithologies contained in the Hudson Strait drift indicate a Labradorean provenance. Large-scale bedrock molding and the distribution of cirques indicate NE-flowing ice has been dominant throughout the middle and late Quaternary. Radiocarbon dates of in situ shells confirm that deglaciation began more than 11,000 yr ago, with the Frobisher Bay coast becoming ice free by 9300 yr ago. Five dates from Hudson Strait suggest that the strait was deglaciated before 9000 yr BP. However, ice from the Labradorean Sector recrossed Hudson Strait during the Cockburn Substage, about 8500 yr ago, damming drainage from the west. Final retreat of Labradorean ice from Baffin Island was complete by 8000 yr ago, at which time the sea was able to penetrate Hudson Bay.

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CONSTRAINING GLACIAL HISTORY AND PROCESS ON MOUNT MANSFIELD, VERMONT'S HIGHEST PEAK, WITH IN SITU COSMOGENIC 10BE AND 14C

10.1130/abs/2018ne-310323 ◽

2018 ◽

Author(s):

Lee B. Corbett ◽

◽

Paul R. Bierman ◽

Jeremy D. Shakun ◽

P. Thompson Davis ◽

...

Keyword(s):

Glacial History ◽

Cosmogenic 10Be

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North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars

Scientific Reports ◽

10.1038/s41598-021-83329-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. Alexis P. Rodriguez ◽

Kenneth L. Tanaka ◽

Ali M. Bramson ◽

Gregory J. Leonard ◽

Victor R. Baker ◽

...

Keyword(s):

Katabatic Wind ◽

Spiral Pattern ◽

Near Surface ◽

Valuable Source ◽

History Of ◽

North Polar ◽

Human Exploration ◽

Erosional Event

AbstractThe clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.

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Development of a Field Deployable Firebrand Flux and Condition Measurement System

Fire Technology ◽

10.1007/s10694-020-01074-x ◽

2020 ◽

Author(s):

Simone Zen ◽

Jan C. Thomas ◽

Eric V. Mueller ◽

Bhisham Dhurandher ◽

Michael Gallagher ◽

...

Keyword(s):

Imaging Techniques ◽

Time History ◽

Infrared Camera ◽

Thermal Conditions ◽

Particle Characterization ◽

Fire Dynamics ◽

Rate Of Spread ◽

New Instrument ◽

History Of

AbstractA new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

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