Creating a High Resolution DEM of Stony Brook Campus  

The main goal is to create a DEM (Digital Elevation Model) of the Stony Brook Campus and to use this DEM to evaluate the glacial geology of the campus. A DEM is a 3-dimensional shaded relief map that shows topography with changes in color (see Fig. 1a). DEM’s have greatly enhanced the ability to interpret geologic features.  

The U.S. Geological Survey provides DEM’s with 10 foot elevation interval and 10 meter spacing in latitude and longitude based on USGS 1/24,000 7.5 minute quadrangle maps (Fig. 1). Nussbaumer and Clarke Inc for the State University Construction Fund have produced a 2-foot contour interval topographic map of the campus. With this map, I plan to first create a DEM with 0.2 meter spacing and 0.2-meter elevation interval, which will have much higher resolution than the existing DEM. In order to produce a DEM with the minimum byte size, I will then increase the spacing and elevation interval until the quality of the image is reduced. To produce the DEM, I will use GIS (Geographic Information system) software called ArcGIS and its 3D Analyst extension. 

Stony Brook campus is located on the Harbor Hill Moraine, which was formed about 20,000 years ago during the last glacial advance. Many of the glacial topographic features on campus site have been preserved by a one meter thick surface layer of erosion resistant till. Till is an unsorted mixture of compacted clay, silt, sand, gravel, and boulders found at the base of a glacier. According to Tingue, et al (2004) ridges and kettles found in the Ashley Schiff Park Preserve developed by folding and faulting as a result of the pushing action of the glacier a glacial tectonic process. At the south part of campus, we have an outwash plain formed by deposition of sediments by melting streams.  

DEM’s based on 10 foot contour interval and 10 meter spacing have been used by Hanson (2002) and Bennington (2003) to interpret surficial features on Long Island. Given a DEM with higher resolution, I can re-evaluate the geological features found on the Stony Brook campus which are presently interpreted as kettle holes, push moraines, outwash plain and hummocky terrain.  The current DEM image (Fig 1a) based on 10 ft contour interval topographic map (Fig. 1b) has allowed the present evaluations of the topography and features on Stony Brook (Hanson, 2002). Figure 2 shows a portion of the campus with 2ft contours. Compare the contours in the boxes surrounding the Ashley Schiff Park Preserve in Fig. 1b and Fig. 2. It is evident that 2 ft contour map shows much more detail.  We can clearly distinguish the ridges and kettles in the 2ft contour map whereas few features can be seen in the 10 ft contour map. I will in particular be emphasizing the interpretation of the features of the Ashley Schiff Park Preserve and compare them with the folding and faulting models presented by Tingue et al (2004). I will also revise the geology in the science walk for the Ashley Schiff Park Preserve by Gurzynski and Solomon. 

 

Fig 1a DEM based on 10 meter horizontal spacing 10 foot contour elevation interval of the Stony Brook campus. The Ashley Schiff Preserve is in square box. Green has the lowest elevation and red is the highest elevation. The sun is in the northeast at 45^o above the horizon. Fig.1b. on right is the topographic map of same area with 10 foot contour intervals on which the DEM is based.

 

Fig 2 Larger scale topographic map with 2 foot contour of part of Stony Brook campus. The Ashley Schiff Park Preserve is in square box. Note the much greater detail for the topography in the Ashley Schiff Park Preserve as compared to that in Fig. 1b. Scale is

References cited:

 

1- Christopher Tingue, Dan M. Davis, and James D. Girardi “Anatomy of Glacio-tectonic
            Folding and Thrusting Imaged Using GPR in the Ashley Schiff Preserve”
            Program for the Eleventh Conference on "Geology of Long Island and
            Metropolitan New York" April 17, 2004 Dept. of Geosciences, SUNY Stony
            Brook, Stony Brook, NY 

            http://pbisotopes.ess.sunysb.edu/lig/Conferences/abstracts-04/tingue.pdf

 2- Gilbert N. Hanson, “Evaluation of Geomorphology of the Stony Brook-Setauket-Port
            Jefferson Area Based on Digital Elevation Models” March 1, 2002 Dept. of
            Geosciences, SUNY Stony Brook, Stony Brook, NY

            http://pbisotopes.ess.sunysb.edu/reports/dem_2/

 3- J Bret Bennington, “New Observations on the glacial geomorphology of Long Island
            from a Digital Elevation Model (DEM)” Program for the Eleventh Conference on
            "Geology of Long Island and Metropolitan New York" April 12, 2003
            Department of Geology, Hofstra University, Hempstead, NY

http://pbisotopes.ess.sunysb.edu/lig/Conferences/abstracts 03/bennington/index.html

 4- Walter Gurzynski and Reid Solomon, “Ashley Schiff Preserve Science Walk” Earth
            Science Research Project, 2002 Dept. of Geosciences, SUNY Stony Brook, Stony Brook, NY

http://pbisotopes.ess.sunysb.edu/esp/Science_Walks/Schiff/Schiff_Science_walk.htm