"Investigating Post-Glacial Fluvial Geomorphology: Knickpoint Evolution and Canyon Formation in Whetstone Gulf of Tug Hill Plateau, New York"

Andrew Bladen, Thesis 2016

Abstract: The area of Whetstone Gulf in upstate New York State, proves an interesting location for our study applying remote topographic analyses in concert with field-based investigation to analyze landscape evolution. The gulf is a dramatic three-mile long (4.82 km) gorge incised into the eastern side of an upland feature known as Tug Hill Plateau. Whetstone constitutes just one out of seven gorges (in addition to numerous smaller canyons) that all align perpendicular to Tug Hill’s Eastern/Northeastern boundary. That boundary is defined by escarpments which the canyons have incised into forming a suite of first and second order channels that flow into the adjacent Black River Valley. Yet Whetstone stands out as a starker feature compared to the others of the group due to how deeply it has incised both vertically and laterally into the escarpments. This fact drew our study to the gulf itself during preliminary scouting of potential field locations.

Closer examination of Whetstone using Geographic Information Systems (GIS) and literature review of past work highlighted other important features of Whetstone’s setting that further justified its suitability as an interesting initial area to test our methods. Imprints of most recent glacial activity during the Last Glacial Maximum, as well as subsequent post-glacial fluvial drainage development and evolution can be observed presently across the Tug Hill region (Ogilvie 1902, Fairchild 1908, Miller W.J. 1909, Muller 1978, Valentino 2011, Cadwell & Muller 2004).
In addition to Whetstone Gulf’s compelling topography and glacial/post-glacial history, there was one last key observation about Whetstone’s watershed that required exploration. The drainage area feeding into the Gulf’s stream seemed relatively small (it measures just under 20 square kilometers; see Table 2) to have been able to incise a canyon as substantial as Whetstone. The same could be said of the other canyons incised into Tug Hill’s eastern escarpment. The respective drainage areas of all of the canyons is small because of the fact that Tug Hill’s southwest dipping surface carries a majority of drainage to the southwest into the Mohawk Valley.

This study will discuss methods that can be used to collect data needed to start answering questions about Whetstone Gulf by constraining variables involved in underlying quantitative fluvial geomorphology concepts that allow us to compare possible scenarios for Whetstone Gulf’s formation to other similar landscapes. Such questions are as follows: What may or may not have driven this incision? When did this incision occur? How may have variations in drainage areas over time impacted incision rates? By attempting to answer aspects of these questions with data obtained from our methods, the goal is to not only provide a more robust characterization of Whetstone Gulf’s form then we know to exist formerly, but to also give useful insight into knickpoint evolution and canyon formation related to post glacial fluvial drainage development. Our methods included both traditional field investigation and computer based topographic analysis by utilizing computer based GIS software.

Whetstone is one of the few gorges of Tug Hill’s eastern edge that is easily accessible to general public. A rim trail that wraps around both edges of the canyon provided tremendous views and perspective of the Gulf. However, the other gulfs fall in private lands and do not have as many recreational areas based in them. As such it was important for this study to consider the differences in data taken from the field versus that obtained from computer-based GIS methods, because this would ultimately determine how viable each method was for achieving a fuller understanding of fluvial drainage development and canyon formation on Tug Hill. A common problem of field geomorphology investigation is ease of access, especially when considering field sites as densely vegetated as the Tug Hill area. Our findings will show that differences in field and computer based investigations provide different benefits which will be discussed. Doing so will provide best-practice measures for carrying out topographic analysis of fluvial drainage networks, knickpoint evolution, and canyon formation in other similar areas.

Full thesis available. Contact the Geology Department at 540-458-8800.