This study is concerned with the post-Ice Age (Holocene) dunes in the coast segment between Coos Bay on the south and Sea Lion Point on the north. This is the longest strip of dunes along the Oregon coast and extends for a distance of about 55 miles. It is divided into three segments by the Siuslaw and Umpqua Rivers and is interrupted by numerous smaller streams that cross it. The strip has a maximum width of nearly 3 miles at Florence. At places it narrows to less than half a mile, but most of it is more than 2 miles wide. The area where the dunes attain their greatest size, abundance, and variety has been designated the Oregon Dunes National Recreational Area, an administrative division of the Siuslaw National Forest.