Dunetype 3a'
Description The 3rd dunes are all roughly 15 to 20 meters (49 to 66 feet) in height, so it is easy to separate the 2nd dune, that is present throughout most of the Clatsop Plains from the 3rd dune sequence, even though they may occur within 60 meters (197 feet) of each other. The height of the 3rd dune sequence is somewhat confused because of the modern dune overlay (Figures 1 and 4 on the older 3rd dune sequence (Reckendorf, 1995). The 3d and 3c dunes are the only dunes in the Clatsop Plains to occur locally as a wide bench top hundreds of meters wide. The majority of the truncated dune (breaches) in the Clatsop Plains occur in the 3rd dune sequence.