1.Previous
3.Next

Columbia River Gorge. When floodwaters met log- and ice-jams at Kalama in southwest Washington, the water caused a backup that filled the entire Willamette Valley to a depth of 300 to 400 ft above current sea level. Some geologists suggest that the valley flooded in this manner multiple times during the last ice age. (If floodwaters of that magnitude covered Portland (elevation

1.Previous
3.Next