Department of Physical Sciences

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https://hdl.handle.net/20.500.14078/11

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Detrital glass in a Bering Sea sediment core yields a ca. 160 ka Marine Isotope Stage 6 age for Old Crow tephra
(2023) Reyes, Alberto V.; Jensen, Britta J.L.; Woudstra, Shaun H.; Bolton, Matthew S.M.; Buryak, Serhiy D.; Cook, Mea S.; Harvey, Jordan; Westgate, John A.
For decades, the Old Crow tephra has been a prominent stratigraphic marker for the onset of Marine Isotope Stage (MIS) 5e, the last interglaciation, in subarctic northwest North America. However, new zircon U-Pb dates for the tephra suggest that the tephra was deposited ca. 207 ka during MIS 7, with wide-ranging implications for chronologies of glaciation, paleoclimate, relict permafrost, and phylogeography. We analyzed ~1900 detrital glass shards from 28 samples collected at Integrated Ocean Drilling Program Site U1345 in the Bering Sea, which has a well-constrained age model from benthic foraminiferal δ18O. Except for one possibly contaminant shard dated at 165 ka, Old Crow tephra was absent from all samples spanning 220–160 ka. Old Crow tephra appeared abruptly at 157 ka, comprising >40% of detrital shards between 157 and 142 ka. This abrupt increase in the concentration of detrital Old Crow tephra, its absence in earlier intervals, and its presence at low concentrations in all samples between 134 and 15 ka collectively indicate that the tephra was deposited during the middle of MIS 6 with a likely age of 159 ± 8 ka. As a result, the late Quaternary chronostratigraphic framework for unglaciated northwest North America remains intact, and the timing of key events in the region (e.g., bison entry into North America; interglacial paleoclimate; permafrost history; the penultimate glaciation) does not require wholesale revision.
Paleobotanical evidence for Mediterranean climates in the western Canadian Paleoarctic during the late middle Eocene
(2024) West, Christopher K.; Reichgelt, Tammo; Reyes, Alberto V.; Buryak, Serhiy D.; Staniszewska, Kasia J.; Basinger, James F.
Paleogene age deposits east of the Fifteenmile River, northwest of Dawson City, Yukon, Canada preserve a diverse high-latitude fossil flora. Here, we provide new data on the age of the fossil site based on laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dating of tephra zircons, paleobotanical paleoclimate reconstructions, and growing season length estimates based on photoperiod. These new data indicate an age of the Fifteenmile River fossil locality as late middle Eocene and likely within the Middle Eocene Climatic Optimum episode. The paleoflora-based paleoclimate reconstruction indicates the region was relatively wet and warm with non-freezing winters, but also experienced seasonal dryness, with an approximate 7 months long growing season as suggested by photoperiod. We interpret this paleoclimate as summer dry and winter wet—a climate analogous to modern day warm Mediterranean climates in the Köppen-Geiger climate classification system. These findings provide a new perspective on the past climate and environment of high-latitude ecosystems during warm greenhouse intervals and contribute to our understanding of the Earth's climate history and its potential future changes.
Palm phytoliths in subarctic Canada imply ice-free winters 48 million years ago during the late early Eocene
(2025) Siver, Peter A.; Reyes, Alberto V.; Pisera, Andrzej; Buryak, Serhiy D.; Wolfe, Alexander P.
Background and Aims: Phytoliths are microscopic siliceous structures produced in specific tissues by many plant families. The morphological features of phytoliths are diagnostic for many plant taxa and, given their inorganic composition, often become part of the fossil record. We used phytolith remains from lacustrine sediments to document the conclusive presence of Arecaceae (palms) in subarctic Canada during the late early Eocene (48 Ma). Methods: Palm phytoliths and aquatic microfossils were extracted from lacustrine mudstones in a drill core taken from the Giraffe kimberlite pipe locality using a combination of acid and oxidation treatments under low heat. Light microscopy and scanning electron microscopy were used to identify, examine and image the microfossils. Key Results: Spherical echinate-shaped palm phytoliths with cone-shaped surface tubercles, likely belonging to the tribe Trachycarpeae (subfamily Coryphoideae), were uncovered in 45 strata over a 37-m section of core. We further document in situ linear arrays of phytoliths, or stegmata, from partially decomposed palm foliage. Additionally, four aquatic organisms, largely restricted to warm subtropical and tropical localities today, were also uncovered in the same strata harbouring the palm phytoliths. Conclusions: The presence of palm phytoliths allows inference of a warm regional climate during the late early Eocene, with mean cold-month temperatures above freezing despite prolonged winter darkness. This conclusion is supported by the presence of multiple warm-water aquatic organisms that grew extensively in the maar lake. Our findings will help to document the extent and timing of perennial ice formation in the northern hemisphere during the Cenozoic. Finally, the discovery of stegmata documents that this morphological trait had evolved by early Eocene.
A new, Late Cretaceous gonorynchiform fish in the genus Notogoneus from drill core of crater-lake deposits in a kimberlite maar, Northwest Territories, Canada
(2022) Grande, Terry C.; Wilson, Mark V.H.; Reyes, Alberto V.; Buryak, Serhiy D.; Wolfe, Alexander P.; Siver, Peter A.
The Gonorynchiformes are a group of mostly marine fishes that are the sister group to the Otophysi (e.g., carps, tetras, catfishes). They include milkfishes (family Chanidae) and beaked sandfishes (family Gonorynchidae) among extant taxa. The only freshwater genus is the strictly fossil †Notogoneus, which until now contained eight species of Late Cretaceous to early Miocene age. A ninth species, †Notogoneus maarvelis, sp. nov., is described here from a single, small specimen found in a diamond-exploration drill core into strata deposited in a kimberlite maar lake in northern Canada. The maar crater was formed by the explosive emplacement of the “Wombat” kimberlite pipe, one of many in the nearby region. The new species is the oldest known member of the genus †Notogoneus and is dated by U–Pb geochronology on associated tephras as early Campanian or about 82 Ma. Although very small, the type and only specimen is very similar in morphology, meristics, and body proportions to the type species †N. osculus. The most important difference is that the origin of the pelvic fin in the new species is beneath vertebral centrum 26, whereas the origin of the dorsal fin is above vertebral centrum 20. In †N. osculus, in contrast, the two fins both originate opposite centrum 22 or 23. The new species is the only one known among those of †Notogoneus or the extant Gonorynchus in which the pelvic fin origin is well behind that of the dorsal fin. The new species agrees with †N. osculus and other congenerics in key attributes of the genus †Notogoneus, including subopercular clefts and, in the caudal skeleton, autogenous parhypural plus hypurals 1 and 2. The bones of the new species ossified at a much smaller size than did those of young individuals of †N. osculus, suggesting that the new species likely attained a much smaller adult size as well. This small, new species, as well as other unidentified fish fragments, was discovered in a core into maar-lake deposits within otherwise fossil-poor areas of the North American craton. Such discoveries highlight the potential importance of maar lakes and similar crater-lake settings for revealing more about fish diversity in the Late Cretaceous than has been previously
Solution structure of the broad-spectrum bacteriocin garvicin Q
(2025) Mallett, Tyler; Lamer, Tess; Aleksandrzak-Piekarczyk, Tamara; McKay, Ryan T.; Catenza, Karizza; Sit, Clarissa; Rainey, Jan K.; Towle-Straub, Kaitlyn M.; Vederas, John C.; van Belkum, Marco J.
Class IId bacteriocins are linear, unmodified antimicrobial peptides produced by Gram-positive bacteria, and often display potent, narrow-spectrum inhibition spectra. Garvicin Q (GarQ) is a class IId bacteriocin produced by the lactic acid bacterium Lactococcus garvieae. It stands out for its unusual broad-spectrum antimicrobial activity against various bacterial species, including Listeria monocytogenes, Pediococcus pentosaceus, Carnobacterium maltaromaticum, Enterococcus faecalis, and Lactococcus spp. Its protein target is the mannose phosphotransferase system (Man-PTS) of susceptible bacterial strains, though little is known about the precise molecular mechanism behind GarQ’s unusual broad spectrum of activity. In this work, 13C- and 15N-labelled GarQ was recombinantly produced using our previously described “sandwiched” protein expression system in Escherichia coli. We also developed a protocol to purify a uniformly labelled sample of the small ubiquitin-like modifier His6-SUMO, which is produced as a byproduct of the expression procedure. We demonstrated its use as a “free” protein standard for 3D NMR experiment calibrations. The GarQ solution structure was solved using triple-resonance nuclear magnetic resonance (NMR) spectroscopy and was compared with the structures of other Man-PTS-targeting bacteriocins. GarQ adopts a helix–hinge–helix fold, which is contrary to its structural predictions according to AlphaFold 3.
Computational analysis of upscaled fibrotic liver multi-lobule flows and metabolism
(2024) Coombe, Dennis; Wallace, Cooper; Rezania, Vahid; Tuszynski, Jack A.
The modeling of fibrotic effects on fluid flow and metabolism in the liver can be computationally challenging. This paper combines innovative concepts based on fundamental physics to address such issues at the level of the liver functional unit, the lobule, and upscales and extends this to a multi-lobule tissue scale analysis. Fibrosis effects on fluid flow and metabolism are introduced using percolation theory and its consequences are explored for single lobule and multi-lobule patterns, without and with distortion.
Evaluating continental channel-hosted Lockeia orientation as a paleoflow indicator: insights from the Jurassic Brushy Basin Member, Western United States
(2025) King, M. Ryan; Timmer, Eric R.; Furlong, Carolyn M.; Gingras, Murray K.; Hayes, Derek A.; Nadon, Gregory C.; Tweet, Justin S.; Santucci, Vincent L.
Although bivalves can orient infaunal body position to current direction, trace fossils of bivalves have rarely been corroborated against paleocurrent directions determined from physical sedimentary structures. This study compares Lockeia (bivalve-generated trace fossil) orientation and length to the three-dimensional bedform cross-strata dip direction from fluvial deposits at two localities in the Late Jurassic Brushy Basin Member (Morrison Formation) of the western United States. Lockeia mean orientation at each site are comparable, but tangential, to physical sedimentary structure mean orientations. Comparing accuracy (within one standard deviation) and precision (within two standard deviations) in-context of five macroform surfaces, the Lockeia measurements are more accurate indicators of current direction than the physical sedimentary structures. Conversely, the physical sedimentary structures are more precise than the Lockeia measurements. This dissimilarity is partly a function of the variability of cross-stratum dip orientation produced by three-dimensional bedforms resultant from the tangential nature of the bedform, its preservation, and the method by which these are measured. Lockeia has greater paleocurrent representation accuracy than physical sedimentary structures since it is a linear measurement rather than a collection of measurements that can be tangential to paleoflow. Lockeia measurements show shifts vertically and laterally with macroform changes indicating potential use for identifying local changes in paleocurrent direction.
Locomotion traces emplaced by modern stalkless comatulid crinoids (featherstars)
(2023) Myers, Reed A.; Furlong, Carolyn M.; Gingras, Murray K.; Zonneveld, John-Paul
Modern crinoids have the ability to use their arms to crawl along the sea floor and some are capable of swimming short distances. The first and only evidence of crinoid locomotion reported from the rock record was described from the Middle Jurassic of the Cabeço da Ladeira Lagerstätte (Portugal) resulting in description of the ichnotaxon Krinodromos bentou. Although the mechanics of crinoid movement are well documented the morphological ranges of crinoid motility tracks are unknown. This study uses observations of crinoid movement and their effects on sediment using modern comatulid crinoids to propose possible trace fossil morphologies. Using 20 experimental trials supported by photography, video analyses, 3D orthogrammetry and resin casting, the morphological ranges of crinoid motility tracks are included in five distinct morphologies attributed to ambling, crawling, walking, running, and landing/taking-off traces, the latter of which are emplaced before and after swimming. Traces produced by ambling occur as epigenic hook-shaped grooves. Crawling traces comprise closely spaced hook-shaped grooves and ridges preserved in concave and convex epirelief. Walking traces consist of semi-bilaterally symmetrical collections of three or more grooves, and associated ridges, preserved in convex and concave epirelief. Running traces consist of semi-bilaterally symmetrical collections of one to three straight to semi-sinusoidal grooves and associated ridges preserved in concave and convex epirelief. Landing/taking-off traces are mounded features preserved in convex epirelief, with grooves radiating from the center. The five trace types described in this paper provide insight into morphological features that can be associated with modern crinoid activities and used to identify crinoid trace fossils, which are rarely reported, in the rock record.
Induced or natural? Toward rapid expert assessment, with application to the Mw 5.2 Peace River earthquake sequence
(2023) Salvage, Rebecca O.; Eaton, David W.; Furlong, Carolyn M.; Dettmer, Jan; Pedersen, Per K.
Based on information available at the time, several questionnaire‐based schemes have been developed to provide a qualitative assessment of whether a specific earthquake (or earthquake sequence) was likely induced by anthropogenic activities or is inferred to be natural. From a pragmatic perspective, the value of this assessment is arguably the greatest in the immediate aftermath of an event (hours to days), because it could then better serve to guide regulatory response. However, necessary information is often incomplete or uncertain, and there remains a lack of scientific consensus on the most distinctive attributes of induced (vs. natural) earthquake sequences. We present a case study of the 5.2 Peace River earthquake sequence (Alberta, Canada), evaluated using two published frameworks for origin interpretation. The Alberta Energy Regulator initially considered the sequence to be natural, but a study published ~4 mo later came to the opposite interpretation. Prior to this publication, we convened a panel of experts who completed questionnaires as set out by the frameworks; results using both schemes indicate that experts believe the sequence was likely induced. Based on these expert responses, we critically evaluate information that was available publicly in the weeks to months following the mainshock on 30 November 2022; reassess the relative importance of various components of the questionnaires from a parsimonious, rapid‐response perspective; and consider other types of information that could be critical for near‐real‐time assessment of whether an event was induced or natural.
Biodegradation in oil sands process-affected water: a comprehensive laboratory analysis of the in situ biodegradation of dissolved organic acids
(2024) Asiedu, Evelyn; Zhao, Kankan; Anwar, Mian Nabeel; Ross, Matthew S.; Balaberda, Amy-lynne; Ulrich, Ania C.
Oil sands process-affected water (OSPW) is a by-product of the extraction of bitumen, and volumes of OSPW have accumulated across the Alberta oil sands region due to the governments zero-discharge policy. Some dissolved organics in OSPW, including toxic naphthenic acids (NAs), can be biodegraded in oxic conditions, thereby reducing the toxicity of OSPW. While there has been much focus on degradation of NAs, the biodegradation of other dissolved organic chemicals by endogenous organisms remains understudied. Here, using the HPLC–ultrahigh resolution Orbitrap mass spectrometry, we examined the microbial biodegradation of dissolved organic acids in OSPW. Non-targeted analysis enabled the estimation of biodegradation rates for unique heteroatomic chemical classes detected in negative ion mode. The microcosm experiments were conducted with and without nutrient supplementation, and the changes in the microbial community over time were investigated. Without added nutrients, internal standard–adjusted intensities of all organics, including NAs, were largely unchanged. The addition of nutrients increased the biodegradation rate of O2− and SO2− chemical classes. While anoxic biodegradation can occur in tailings ponds and end pit lakes, microbial community analyses confirmed that the presence of oxygen stimulated biodegradation of the OSPW samples studied. We detected several aerobic hydrocarbon-degrading microbes (e.g., Pseudomonas and Brevundimonas), and microbes capable of degrading sulfur-containing hydrocarbons (e.g., Microbacterium). Microbial community diversity decreased over time with nutrient addition. Overall, the results from this study indicate that toxic dissolved organics beyond NAs can be biodegraded by endogenous organisms in OSPW, but reaffirms that biological treatment strategies require careful consideration of how nutrients and dissolved oxygen may impact efficacy.
Research recast(ed): S3E15 - Creative chemists on creating a cleaner, greener future for everyone
(2024) Leschyshyn, Brooklyn; Smadis, Natalie; Lee, Roland; Mundle, Trevor
On today’s episode we had the pleasure of being joined by Dr. Roland Lee and Trevor Mundle. The two test our preconceived notion of the truth behind environmentally friendly products. Dr. Roland Lee and Trevor Mundle collaborate between the MacEwan lab and Green Tech, bringing together experts in chemistry, finance, investment, and sustainable practices. They use cutting-edge pyrolysis technology to convert various feedstocks into valuable products, which reduces emissions, fossil fuel dependencies, water usage, and landfill needs. Their objective is to transform waste streams into valuable resources.
Research recast(ed): S3E3 - Bringing young minds to MacEwan through experiences, experiments, and fun with Dr. Emily Milne, Dr. Kaitlyn Towle, and Steven Campbell
(2023) Leschyshyn, Brooklyn; Smadis, Natalie; Milne, Emily; Towle, Kaitlyn; Campbell, Steven
On today’s episode, we talk to Dr. Emily Milne, Kaitlyn Towle, and Steven Cambell about MacEwanCYU. With the help of MacEwan, students from Ben Calf Robe can learn about what the university has to offer. Their project helps to inspire young minds and invite them to aspire to a secondary education.
Research recast(ed): MacEwan Celebrates Month of Scholarship - Dr. Erin Walton
(2022) Ekelund, Brittany; Cave, Dylan; Walton, Erin
Today’s episode is literally out of this world as we talk about meteorites, asteroids and moon rocks with geologist Dr. Erin Walton, an associate professor in the Department of Physical Sciences at MacEwan University, whose primary research focuses on shock metamorphism recorded in martian meteorites. Along the way, we’ll discuss mentorship, space colonization and the economic benefit of finding impact craters. We will also get a glimpse into Dr. Walton’s new exciting avenue of research into her all-time favorite asteroid, 4-Vesta.
Research recast(ed): MacEwan celebrates month of scholarship - Dr. Samuel Mugo
(2022) Ekelund, Brittany; Cave, Dylan; Mugo, Samuel
Today we learn about smart technology and the democratization of health through point-of-need sensors with Dr. Samuel Mugo, a professor of analytical chemistry at MacEwan University, whose research program involves the use of smart sensor technology for human and animal health and wellness, as well as agri-food chemical analysis. Along the way, we will learn about the United Nations Sustainable Development goals, and find out how chemistry and technology can come together to address food security and help people take control of their physical and mental wellness.
Using GIS and remote sensing to monitor industrial impacts to archaeological sites in the Athabasca Oil Sands of Alberta
(2021) Wadsworth, William T. D.; Dersch, Ave; Woywitka, Robin; Supernant, Kisha
The Athabasca Oil Sands (AOS) region of Alberta has one of the densest accumulations of known archaeological sites, and possibly the most archaeological sites at risk, in the country. Expanding industrial development has been a characteristic of this region for decades, and as a result, abundant archaeological work has been done and regulatory requirements put in place to mitigate site disturbance. Until recently, there has been little quantitative evidence to assess human impact on archaeological resources in the region. The goal of this paper is to raise awareness of the critical need to incorporate new archaeological remote sensing strategies to improve site monitoring approaches. We present methods and results from our GIS-based analysis that seeks to locate and partially characterize impacted sites. We argue that combining publicly accessible remote sensing products with geospatial archaeological site information allows for better documenting and monitoring of industry impacts in the AOS. We show that 43% of all sites sampled (n=1943) are disturbed. Of these sites, 160 were potentially affected by Historical Resources Act non-compliant impacts (including five HRV 1 sites). We contextualize our results within current systemic challenges and we recommend the incorporation of community monitoring programs to ground-truth similar GIS analyses and increase our ability to effectively monitor industrial impacts to archaeological sites.
Topographic setting of archaeological survey in the Boreal Forest of Alberta
(2021) Woywitka, Robin; Michalchuk, Benjamin
The archaeological record of the Canadian Boreal Forest is dominated by shallowly buried sites with little to no datable artifacts or stratigraphy. This has led to characterizations of the region as an area of low scientific interpretive value. However, the factors that underlie this skew to shallow sites are rarely formally examined. Here we use a geomorphon-based terrain classification to assess the role of topographic setting in the placement of archaeological survey points. Our results show that there is considerable bias in current archaeological survey methods towards landforms that disperse sediment. This reduces the likelihood of finding deeply buried or stratified sites and calls into question the assertion that datable sites are largely absent from the region. We recommend that increased sampling of low-lying terrain should be a regular component of Boreal Forest survey methodology.
Late Pleistocene and Early Holocene obsidian in Alberta and human dispersal into North America’s ice-free corridor
(2023) Kristensen, Todd; Allan, Timothy E.; Ives, John W.; Woywitka, Robin; Yanicki, Gabriel; Rasic, Jeffrey T.
We utilize pXRF to source the oldest obsidian artifacts in Alberta, Canada. The province lacks obsidian outcrops and hosts much of the late Pleistocene Ice-Free Corridor, the northern and southern ends of which are in proximity to obsidian outcrops in Yukon, Alaska, Idaho, and Wyoming. The early presence of these obsidians in Alberta informs models of human dispersion. Results point to an early establishment of relationships in the central Ice-Free Corridor that reached into Oregon, Idaho, and Alaska. Alberta appears to have been entered by people from the south who had ties to the Pacific Northwest and Intermountain West. After biotic viability of a full Corridor, limited evidence suggests that northern people from Beringia may have trickled south and admixed with southern populations in the central Corridor region. Upon deglaciation of access routes through the Rocky Mountains, obsidian from western sources in British Columbia arrived relatively quickly in northern Alberta.
Lead (Pb) sorption to hydrophobic and hydrophilic zeolites in the presence and absence of MTBE
(2021) Zhang, Yunhui; Alessi, Daniel S.; Chen, Ning; Luo, Mina; Hao, Weiduo; Alam, Md. Samrat; Flynn, Shannon L.; Kenney, Janice; Konhauser, Kurt O.; Ok, Yong Sik; Al-Tabbaa, Abir
The co-contamination of the environment by metals and organic pollutants is a significant concern, and one such example is lead (Pb) and methyl tert-butyl ether (MTBE) due to their historic use as fuel additives. Clinoptilolite is an abundant and efficient zeolite for metal removal, but the potential interference of co-existing organic pollutants on metal removal, such as MTBE, have rarely been discussed. In this study, a combination of batch sorption tests and synchrotron-based X-ray absorption spectroscopic analyses were employed to investigate Pb sorption mechanism(s) onto clinoptilolite in the presence and absence of MTBE. A comparison was made to synthetic ZSM-5 zeolite to gain insights into differences in Pb binding mechanisms between hydrophilic (clinoptilolite) and hydrophobic (ZSM-5) zeolites. Site occupancy and surface precipitation contributed equally to Pb removal by clinoptilolite, while surface precipitation was the main Pb removal mechanism for ZSM-5 followed by site occupancy. Despite the negligible effect of 100 mg/L MTBE on observed Pb removal from solution by both zeolites, a surface-embedded Pb removal mechanism, through the Mg site on clinoptilolite surface, arises when MTBE is present. This study provides an understanding of atomic-level Pb uptake mechanisms on zeolites, with and without co-contaminating MTBE, which aids in their application in water treatment at co-contaminated sites.
Settling behaviors of microplastic disks in water
(2023) Yang, Ge; Yu, Zijian; Baki, Abul B. M.; Yao, Weiwei; Ross, Matthew S.; Chi, Wanqing; Zhang, Wenming
Microplastic (MP) disks have not been studied for settling behaviors in aquatic environments, which affects the transport and fate of MPs. Therefore, settling experiments were conducted on MP disks of three shapes and four common-seen materials. Lighter MP disks (with density ρs = 1.038 g/cm3 and length l ≤ 5 mm) followed rectilinear vertical trajectories, while heavier MP disks (ρs = 1.161–1.343 g/cm3 and l = 5 mm) followed zigzag trajectories with oscillations and rotations. The mean terminal settling velocities of MP disks were 19.6–48.8 mm/s. Instantaneous settling velocities of heavier MP disks fluctuated. Existing formulas could not accurately predict the settling velocity of MP disks; thus, a new model was proposed with an error of 15.5 %. Finally, the Red - I* diagram (Red is the disk Reynolds number and I* is the dimensionless moment of inertia) was extended for MP disks to predict settling trajectories.
Ice, mountains, and people: applying a multi-proxy approach to reveal changes in Alberta’s alpine ecosystems through ice patch research
(2023) Tirlea, Diana; Kristensen, Todd; Osicki, Aaron; Jensen, Britta; Williams, Krista; Caners, Richard; Lumley, Lisa; Woywitka, Robin
Glacial archaeology has grown and progressed rapidly in recent decades with technological innovations and shifting socio-political issues. However, research on ice patches in the Canadian Rocky Mountains is in its infancy. While Holocene glacial ice retreat, advance, and morphology are well studied in Canada, ice patches in general tend to be understudied because of their limited geomorphological impact on landscapes. This oversight is concerning as their isolated nature, lower elevation, and small mass make ice patches even more susceptible to climate change than glaciers. The importance of documenting these features is heightened by a persisting but tenuous biological importance to a range of modern species. The lack of flow in ice patches also makes them excellent archives of palaeoenvironmental and organic-based cultural materials, as layers of ice and preserved contents are not as distorted as they may be by flow in glaciers.

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