Using GIS to Quantify Patterns of Glacial Erosion on Northwest Iceland: Implications for Independent Ice Sheets

Glacial erosion patterns on northwest Iccliind are quantified using a Geographic Information System (GIS) in order to interpret subglacial characteristics of part of northwest Iceland affected by ice sheet glaciation. Ice scour lake density is used as a proxy for glacial erosion. Erosion classes are interpreted from variations in the density of lake basins. Lake density was calculated using two dilTerent methods: the first is sensitive to the total number of lakes in a specific area, and the second is sensitive to total lake area in a specific area. Both of these methods result in a value for lake density, and the results for lake density calculated using the two methods are similar. Areas with the highest density of lakes are interpreted as areas with the most intense erosion with the exception of alpine regions. The highest density of lakes in the study area exceeds 8% and is located on upland plateaus where mean elevations range from 400 to 800 m a.s.l. Low lake density (0-2%) is observed in steep alpine areas where steep topography does not favor lake development. The G!S analysis is combined with geomorphic mapping to provide ground truth for the GIS interpretations and to locate paleo-ice flow indicators and landforms. The patterns identified in this study illustrate distinct regions of glacial erosion and flow paths that are best explained by two independent ice sheets covering northwest Iceland during the Last Glacial Maximum (LGM). Areas of alpine glacial landforms and the presence of nunataks within the glaciated region support interpretations that Ice-free regions or cold-based ice cover existed on parts of northwest Iceland during the LGM. The methods developed in this study are easily transferable to other formerly glaciated regions and provide tools to evaluate subglacial properties of former ice sheets. The data generated yield important subglacial boundary conditions for ice sheet models of Iceland

parametri qualitativi e quantitativi all'esame videocapillaroscopico di pazienti affeti da sclerosi sistemica complicata da ipertensione polmonare

Scopo della tesi: valutare all’esame videocapillaroscopico (VCP) di una serie di pazienti affetti da sclerosi sistemica progressiva (SSc) con ipertensione polmonare (PAH) i parametri qualitativi e quantitativi predittivi di impegno viscerale e dello sviluppo di ulcerazioni cutanee, e correlare le alterazioni osservate alla gravità dell’ipertensione polmonare. Metodi: sono stati studiati lo scleroderma pattern, la densità capillare, la dimensione ed il numero dei megacapillari in una serie di 14 pazienti affetti da SSc con PAH diagnosticata tramite cateterismo cardiaco. Risultati: la VCP nel 100% dei casi ha mostrato aree avascolari alla valutazione qualitativa (pattern VCP late); la densità dei capillari correla inversamente con i valori di ipertensione polmonare (p2.94, i valori di PAH e sviluppo di ulcere cutanee. Conclusioni: la riduzione della densità capillare è associata alla gravità della PAH, ma non la dimensione delle anse capillari. I parametri di VCP quantitativi (CSURI) nella serie osservata di soggetti SSc-PAH perdono predittività di sviluppo di ulcere cutanee. Ciò suggerisce che alcune alterazioni micro vascolari giocano un ruolo nello sviluppo della PAH probabilmente indipendente dalle altre manifestazioni cliniche

Holocene Sediment Magnetic Properties Along a Transect from Isafjardardjup to Djupall, Northwest Iceland

Holocene changes in terrestrial provenance and processes of sediment transport and deposition are tracked along a fjord-to-shelf transect adjacent to Vestfirdir, Iceland, using the magnetic properties ofmarine sediments.Magnetic susceptibility (MS) profiles of 10 cores (gravity and piston) were obtained onboard using a Bartington MS loop. Remanent magnetizations were measured at 1-cm intervals from u-channel samples taken from six cores on a cryogenic magnetometer. Between six and nine alternating field demagnetization steps were used to isolate the characteristic magnetization directions. The chronologies of the cores used in this study were determined from AMS14 C dates on mollusks and foraminifera and contrained by the regional occurrance ofthe 10,200 6 60 cal yr. BP Saksunavatn tepha. Correlative fluctuations in magneticconcentration are noted between the fjord and shelf sites, though these fluctuations are partiallymasked by regional variations in carbonate content. The onset of Neoglaciation is interpreted by changes in magnetic properties including an increase in mass magneticsusceptibility that began approximately 3000 cal yr. BP. The maximum angular deviation and the median destructive field (generally 20 mT) suggest that the natural remanent magnetization is carried by a coarse ferrimagnetite mineralogy, likely magnetite or titano-magnetite. Reproducible paleomagnetic inclination values are observed in several records, including a nearly vertical inclination around 8000 cal yr. BP, suggesting that the magnetic pole may have been proximal to Iceland, followed by an interval of much shallower inclination (6000–7000 cal yr. BP)

The Melting ‘Crown of the Continent’: Visual History of Glacier National Park

Glacier National Park (GNP), located in northwest Montana, US, was signed into existence on 11 May 1910 by then President William Howard Taft. Conservationist George Bird Grinnell was instrumental in lobbying for the park’s creation and negotiated the sale with the Blackfeet Indians. As an editor of the outdoor magazine Field and Stream, Grinnell learned about the region from writer James Willard Schultz and made his first visit there in 1885. Enticed and amazed by the glaciers of the area, the high Rocky Mountain alpine terrain, and the flora and fauna that thrived here, Grinnell advocated for the creation of the park, nicknaming it the “Crown of the Continent.” Grinnell recognized glaciers as a geological wonder. As historian Gerald Diettert records in his 1992 book, Grinnell called the glaciers the “jewels” in the crown. Setting aside land to enjoy the glaciers seemed like a logical means to conserve the landscapes and ecosystems that they supported. Yet today, just about a hundred years from when the park was founded, the glaciers that form GNP’s snow-capped crown are close to extinction. [excerpt

Comparison of Periglacial Block Fields and Talus Slopes in South-Central Pennsylvania and Northern Maryland

Relict periglacial boulder fields, or block fields, are scattered across south-central Pennsylvania and northern Maryland (e.g. Potter and Moss, 1968; Denn et al 2018). This pilot study uses a combination of digital analyses using Google Earth Pro and fieldwork to investigate block fields at different scales. Fieldwork focused on two block fields, which were compared with fieldwork conducted on two talus slopes. The block fields studied were Raven Rock Hollow in Maryland and River of Rocks at Hawk Mountain in Pennsylvania, and the talus slopes were located at Catoctin Mountain, Maryland and Waggoner’s Gap, Pennsylvania. The importance of geomorphic processes on formation of block fields compared to talus slopes was examined as part of this pilot study

Readin\u27, Writin\u27, An\u27 \u27rithmetic: Literacy Strategies In High School Mathematics

Stagnant growth on national standardized tests in mathematics and reading and a focus on disciplinary literacy in the Common Core State Standards in ELA, history/social studies, science, and technical subjects has prompted a resurgence in utilizing literacy strategies in the content areas in high school. While literacy standards in mathematics are not explicitly identified in the Common Core State Standards, there may be a place for the use of literacy strategies in high school mathematics. This study explored the relationships between students’ mathematics and reading achievement scores at a small, suburban high school and the implementation of a school wide literacy program to inform curriculum development and instructional strategies. The reading and mathematics achievement of students in ninth through eleventh grade was retroactively analyzed to identify changes in student achievement over a two-year period. In the first year, the ninth grade cohort showed statistically significant improvement on both measures of mathematics achievement. Within this ninth grade cohort, students who qualified for free lunches also saw statistically significant improvement in mathematics. None of the other groups showed improvement on both measures of mathematics achievement or reading achievement. In the second year, both the ninth and tenth grade cohorts showed statistically significant increases on both mathematics and reading achievement. Within each of these grade level cohorts, females and white students also saw statistically significant increases in both mathematics and reading. The eleventh grade cohort did not have any significant increases on either measure. On the state top-to-bottom ranking, this high school has moved from the 4th percentile to the 25th percentile during the implementation of the school wide literacy program. While national standardized tests have shown little to no improvement over the last several administrations, this small, suburban high school has seen continued growth over the last several years. Though the results of this study cannot be used to determine a causal relationship between the implementation of literacy strategies and the academic achievement of students in either mathematics or reading, it does provide a case for further investigation into such a relationship

Spatial Analysis of Cirques from Three Regions of Iceland: Implications for Cirque Formation and Palaeoclimate

This study is a quantitative analysis of cirques in three regions of Iceland: Tröllaskagi, the East Fjords and Vestfirðir. Using Google Earth and the National Land Survey of Iceland Map Viewer, we identified 347 new cirques on Tröllaskagi and the East Fjords region, and combined these data with 100 cirques previously identified on Vestfirðir. We used ArcGIS to measure length, width, aspect, latitude and distance to coastline of each cirque. Palaeo‐equilibrium‐line altitudes (palaeo‐ELAs) of palaeo‐cirque glaciers were calculated using the altitude‐ratio method, cirque‐floor method and minimum‐point method. The mean palaeo‐ELA values in Tröllaskagi, the East Fjords and Vestfirðir are 788, 643 and 408 m a.s.l, respectively. Interpolation maps of palaeo‐ELAs demonstrate a positive relationship between palaeo‐ELA and distance to coastline. A positive relationship between palaeo‐ELA and latitude is observed on Vestfirðir, a negative relationship is observed on Tröllaskagi and no statistically significant relationship is present on the East Fjords. The modal orientation of cirques on Tröllaskagi and Vestfirðir is northeast, while orientation of cirques in the East Fjords is north. Palaeo‐wind reconstructions for the LGM show that modal aspect is aligned with the prevailing north‐northeast wind directions, although aspect measurements demonstrate wide dispersion. Cirque length is similar on Tröllaskagi and the East Fjords, but cirques are approximately 200 m shorter in Vestfirðir. Cirque widths are similar in all three regions. Comparisons with a global data set show that cirques in Iceland are smaller and more circular than cirques in other regions of the world. Similar to glaciers in Norway and Kamchatka, our results demonstrate that access to a moisture source is a key parameter in determining palaeo‐ELAs in Iceland. Temperatures interpreted from palaeo‐ELA depressions suggest that these cirques may have been glaciated as recently as the Little Ice Age