Northeastern Section - 54th Annual Meeting - 2019

Paper No. 42-2
Presentation Time: 1:30 PM-5:25 PM


MCKENZIE, Marion A.1, PRINCIPATO, Sarah M.1 and BENEDIKTSSON, Ívar Örn2, (1)Environmental Studies, Gettysburg College, 300 N. Washington St, Box 2455, Gettysburg, PA 17325, (2)Institute of Earth Sciences, University of Iceland, Askja, Sturlugata 7, Reykjavík, IS-101, Iceland

The properties of streamlined landforms and paleo-flow indicators in the valley of Bárðardalur in north Iceland and northwestern Pennsylvania (NW PA) were quantified using a combination of spatial analyses, fieldwork, and sediment analysis. The study region in Iceland is primarily composed of basaltic bedrock from the Pliocene and Pleistocene epochs, while the study region of Pennsylvania is sedimentary rock formed during the Devonian period. A combination of satellite imagery from Google Earth, the National Land Survey of Iceland Map Viewer, and a 5m mosaic of the Arctic Digital Elevation Model were used to identify drumlins and megascale glacial lineations (MSGL) in Iceland, and Pennsylvania Spatial Data Access and 7.5 minute topographic maps from the United States Geologic Survey were used to identify similar features in northwestern Pennsylvania. The perimeter of each landform was traced manually either in Google Earth or in ArcMap using available data sets. Quantitative analyses were conducted in ArcGIS using the manually collected data set. Landforms were classified as either drumlins or MSGL by their elongation ratio, with drumlins having a ratio of < 10:1 and MSGL having a ratio of ≥ 10:1. In Iceland, at least 148 streamlined landforms were identified in Bárðardalur using Google Earth, with 69 drumlins and 79 MSGL. Average elongation ratio and parallel conformity of these landforms is 11.7:1 and 6.03 degrees, respectively, and the low parallel conformity value indicates uniform ice flow direction. The modal orientation of long axes of streamlined landforms is 317.8 degrees, demonstrating that ice flowed from Bárðardalur into the Skjálfandi Bay. The landforms present in Bárðardalur have an average density of 1.85 landforms per 1 km2 , and packing ranges from 0.0002 - 0.67 landform surface area per km2, with an average value of 0.14 landform surface area per km2. In northwestern Pennsylvania, at least 312 streamlined landforms were identified, with 304 drumlins and 8 MSGL. The average elongation ratio of landforms in NW PA is 4.38:1 and the distribution is positively skewed. Parallel conformity of the landforms in NW PA is 8.48 degrees, and the modal orientation of long axes of streamlined landforms is 150.6 degrees. The small number of MSGL in NW PA suggests slower ice flow velocity than in Bárðardalur, Iceland. Analyses of packing and density for NW PA are in progress. Factors such as bedrock composition and geothermal gradient are being analyzed to understand how each of these variables influences formation of streamlined landforms.