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Ascent to Effingham County High Point-GIS scouting on 2018-10-10

Climber: Tom Layton

Date:Wednesday, October 10, 2018
Ascent Type:No Summit Goal
Point Reached:Effingham County High Point - GIS scouting
    Location:USA-Georgia
    Elevation:135 ft / 41 m

Ascent Trip Report

The USGS quads for Effingham County have 5-foot contours and show 40 areas that reach 135 feet. In preparation for an upcoming trip, I looked up the Effingham County GIS map (http://www.effinghamcounty.org/190/Interactive-GIS-Map) and was pleasantly surprised to find 2-foot contours. If we can trust these, we can narrow down the possibilities.

The highest spot elevations in the county are 138, which are found on Old Louisville Road and Old Elam Cemetery Road near their intersection. This is on the western edge of COHP Area 2, which is the largest of the 135-foot contours on the USGS quads. Peakbagger labels it "Huge Area" and marks it near the center of the contour.

Indeed, the Effingham GIS map shows a few 138 contours near Old Louisville Road. These are south of the USGS spot elevations and west of the spot marked on the Peakbagger map. See attached screenshot map. They are grouped in two main areas--at N32.480 W85.507 among some trailers or sheds that might be homes to farm workers, and at N32.475 W81.506 in an open field that has been logged since the Effingham map was made. (I'm not sure of the datum on these coordinates--I got them off the Peakbagger maps). Between these two areas is another with some mounds that reach as high as 142. These are almost certainly manmade excavations from the adjacent ponds. There is a similar 140 ridge that parallels the field north of the workers' sheds, but I suspect it is manmade, too.

I checked all 40 COHP areas against the Effingham GIS maps and did not see any others that reached 138--except for a few obviously manmade mounds. Many of them are 136, which may be too close to rule out. It's possible that I might have missed a 138 somewhere.

In particular, I wouldn't rule out the spot listed as Main Summit on Peakbagger (N 32.494, W81.471). This has a spot elevation of 137 on the quad and is enclosed in a 136 contour on the GIS map. It looks like this area is accessible on a dirt road leading N/NE from the Egypt community.

When using GIS/LiDAR maps, I usually look for a two-contour difference before I eliminate possibilities. In this case, 134 feet would be the cutoff. If this is acceptable, we can rule out:
Area 3: 132 feet per GIS.
Area 24: A field of timber inside a loop road southwest of the 138 spot elevation. GIS says this only reaches 130.
Areas 25-26: 134-foot contours on opposite sides of Old Louisville Road at the fork with Elam Cemetery Road.
Areas 27-32. The highest of these are 134 contours: Area 29 appears to be a manmade mound, and Area 31 is a drive-over on Oliver Kildare Road.
Areas 33-36: Along the Screven County line. None of these is above 130, with the possible exception of Area 35, where the contour lines don't go all the way to the county line.
Areas 37-40: Bluffs along the Savannah River. None of them is above 130.

Still, that leaves several square miles of no-man's-land on both sides of GA 17. COHP Areas 4-23 all have 136 elevations according to GIS. Areas 8 and 9 have mounds up to 142 that appear to be manmade. Most of this area is roadless, and the terrain is so flat that gridding would be futile.
Click on photo for original larger-size version.
The Effingham County GIS maps have 2-foot contours, and the only natural-looking 138-foot contours I could find were in two areas east of Old Louisville Road. Note that there are skinny ridges up to 142 around the ponds near the center of the picture, but they are almost certainly manmade. (2018-10-10). Photo by Tom Layton.
Click here for larger-size photo.
Summary Total Data



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