Carolina bay Survey Process Instructions

These pages will be used as a guide to participating in the Carolina Bay Survey.

The subject of the Carolina bay’s geological origins is quite intriguing topic in its own right. One good place to start is on Wikipedia . Their review is fairly extensive, and shows that the debate continues. BTW, the proper title is “Carolina bay”, with lower case b, as it is a general description, not a specific place.

Basically, these are “Carolina bays”:

Photo by George Howard

This next photo of a single bay presents Antioch bay in South Carolina’s Hoke County, as presented in Smithsonian Magazine (9/1997). A high resolution image is available HERE. In addition, the following placemark will take you to Google Earth, and place the viewer in the same position as the camera was for this photo.

Photo by Cameron Davidson for the Smithsonian

View in Google Earth

The survey takes significant advantage of Google Earth and its flexibility to display and work with placemarks, lines and overlays.

The survey utilizes overlay in two ways. First, as a simple replacement for Google Earth’s satellite imagery, but using instead digital elevation maps. The maps are encoded as hue-saturation-value (hsv), and present a false color based on the elevation at that particular point on the earth. Recent improvements in mapping using Laser Imaging, Detection and Ranging (LiDAR) techniques have offered benefit to this survey, as these maps often highlight and accentuate the Carolina bay locations and planforms. A good discussion on LiDAR can be found HERE. For access to a comprehensive on-line educational resource for LiDAR, Penn State offers “GEOGRAPHY 497D: Lidar Technology and Applications”.

We have used DEM data from the USGS and from the Nebraska Department of natural Resources. While we’d like to use LiDAR derived 1/9 arc second data exclusively, it is not available for vast areas of Carolina bays. In those instances, we use USGS 1/3 arc second data. Here is an example of bays with and without the LiDAR overlay:

These screenshots taken from Google Earth also exhibit one of the “Planform Overlays” used in the survey. This oval shape has an arrow, allowing the user to describe the “Inferred Orientation” of a bay by rotating it into the position most appropriate in the user’s perception. The overlay also captures the latitude and longitude of a box surrounding the overlay, allowing for capture of the bay’s length and width. The capture is done by extracting data from the overlay’s text content. Here is the data from the overlay show above:

Step 1

First, we will introduce the user to the “Octant” file , its contents, and its use within the Google Earth GIS program. It also discusses briefly the use of the “planform overlay” in Google Earth as a data capture tool.

Step 2

The second topic will discuss bay identification with and without digital elevation maps (DEM) on the Google Earth virtual globe, and demonstrate how the bay planform overlay is placed and verified.

Step 3

The overlay is discussed in more detail.

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