The Willamette Basin of Oregon is more correctly a valley. The term valley consist of: Passes, craters, basins, ditches, etc. but a valley is differentated by its elongation. At 114 miles long and 60 miles wide, it is not a true bowl or basin. However, there is work to suggest the Willamette Vally is still widening, so please check back on this entry in a couple hundred million years or so. See Willamette Valley