fortdune.jpg (668541 bytes)

    Ground Penetrating Radar (GPR) was used to get a view of the internal structure of the dune.  GPR works by shooting FM radio waves into the ground through the transmitter and receiving the waves through the receiver.  By doing this the GPR system gives us an image of the subsurface layers of the earth.  We were trying to determine if these dunes were longitudinal dunes.  We used the pulse Ekko 1000 system at 225 megahertz.  A reading was taken every ten centimeters.   Below is a segment of the actual data that was collected on the first line that was shot. 

dune1.GIF (24550 bytes)

2dune2.jpg (795109 bytes)

    A second line was shot further in from the road.  This was done to give us a better idea of whether the dune was a longitudinal dune or not.  We used the same system at the same frequency on this line.  Below is a segment of the actual data that was collected at the second site on the dune.

dune22.GIF (22281 bytes)

gravelpit.jpg (155975 bytes)

    We shot the same line with all of the different frequencies that we had.  We did this to see how the different frequencies looked and how deep into the ground they penetrated.  We did this in the gravel pit because we knew what the soil was like here.  As a result we knew what to expect.