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Rock Strength Along A Fluvial Transect Of The Colorado Plateau - Quantifying A Fundamental Control On Geomorphology, Natalie Bursztyn, Joel Pederson

Natalie Bursztyn

Bedrock strength is a key parameter that influences slope stability, landscape erosion, and fluvial incision. Yet, it is often ignored or indirectly constrained in studies of landscape evolution, as with the K erodibility parameter in stream-power models. Empirical datasets of rock strength suited to address geomorphic questions are rare, in part because of the difficulty in measuring those rocks at Earth's surface that are heterolithic, weak, or poorly exposed. Here we present a large dataset of measured bedrock strength organized by rock units exposed along the length of the trunk Green–Colorado River through the iconic Colorado Plateau of the western …

A 70 Year History Of Coastal Dune Migration And Beach Erosion Along The Southern Shore Of Lake Michigan, Zoran Kilibarda, Craig Shillinglaw

Zoran Kilibarda

A study of aerial photographs from the Indiana Dunes National Lakeshore (adjacent to Michigan City, Indiana, United States of America) revealed that from 1938 to 2008 the Lakeshore’s Mount Baldy dune advanced inland 135 m, at an average rate of 1.9 m/year, while the beach north of the dune receded 98 m, at an average rate of 1.4 m/year. The highest rates of Mount Baldy dune movement (3.3 m/year) occurred concurrently (1965–1973) with highest rates of beach erosion (7.2 m/year). The lowest rates of Mount Baldy dune movement (0.3 m/year) occurred in 1958–1965 period. The highest rates of beach accretion …

The Effects Of Surface Water Velocity On Hyporheic Interchange, Timothy Sickbert, Eric Wade Peterson

Eric Wade Peterson

When evaluating hyporheic exchange in a flowing stream, it is inappropriate to directly compare stream stage with subsurface hydraulic head (h) to determine direction and magnitude of the gradient between the stream and the subsurface. In the case of moving water, it is invalid to ignore velocity and to assume that stage equals the net downward pressure on the streambed. The Bernoulli equation describes the distribution of energy within flowing fluids and implies that net pressure decreases as a function of velocity, i.e., the Venturi Effect, which sufficiently reduces the pressure on the streambed to create the appearance of a …

Bedrock Strength And River Metrics: Spatial And Statistical Correlations On The Incision Of The Colorado Plateau, Southwest Usa, Natalie Bursztyn, Joel Pederson

Natalie Bursztyn

Morphology And Origin Of The Fair Oaks Dunes In Nw Indiana, Usa, Zoran Kilibarda, Joseph Blockland

Zoran Kilibarda

The Fair Oaks Dunes (FOD) of NW Indiana, USA is a large (~4500 km2) inland dune field associated with the late Wisconsin deglaciation of the Laurentide Ice Sheet. Meltwaters released by the Michigan, Saginaw, and Huron–Erie lobes transported fluvioglacial sediment through the Kankakee and Tippecanoe Valleys and their tributaries. The texture and composition of the sand in the FOD suggest a Saginaw Lobe origin of sediment with some Huron–Erie Lobe sediment. Sub-mature sand with sub-angular grains and a large feldspar content suggests relatively short distance of transport during two or possibly three dune-building and dune reworking events. We propose a …

Identifying The Stream Erosion Potential Of Cave Levels In Carter Cave State Resort Park, Kentucky, Usa, Eric Peterson, Brianne Jacoby, Toby Dogwiler

Eric Wade Peterson

Cave levels, passages found at similar elevations and formed during the same constant stream base level event, reveal information about paleoclimates and karst geomorphology. The investigation presented here examines how Stream Power Index (SPI) relates to cave levels. The study area, Carter Caves State Resort Park (CCSRP), is a fluviokarst system in northeastern Kentucky containing multiple cave levels. SPI deter-mines the erosive power overland flow based on the assumption that flow accumulation and slope are proportional to potential for sediment entrainment. Part of this digital terrain analysis requires the creation of a flow accumulation raster from a digital elevation model …