At the end of the last ice age ten to fifteen thousand years ago, catastrophic floods occurred approximatly every fifty-five years when the ice dam on Idaho's Clark Fork Valley containing Montana's Glacial Lake Missoula deteriorated letting loose massive amounts of water, ice and debris which flowed across Northern Idaho and Eastern Washington to the Columbia River and Pacific Ocean. The intensity of the rush of water is estimated to have been more that ten times the force of all the worlds rivers combined. The agricultural fertility of the Willamette Valley was instilled by lake bottom sediments deposited by the Missoula Floods.

A Kolk is an extremely strong vortex that develops in deep flows of super fast moving water. A kolk is strong enough to pull a boulder from the bedrock and there are ponds today where water has flowed into the craters. An example of a kolk can be found just north of Wilsonville's Boeckman Road at Coffee Creek.

Pleistocene Megafauna are a diverse variety of large mammals that lived during the Pleistocene epoch from 1.8 million to ten thousand years. Eighty-five percent of them went extinct at the end of the last ice age. Climate change and hunting by indigenous Americans are cited as primary causes for their demise.

The Teratorn is the largest known flying bird with estimated wingspan of over 13 feet. The bird swalloed live prey whole through jaws that opened wide. More reptilian than eagles, Teratorns were similar to the condor and less adept at hunting small animals than eagles and hawks.

The Dire Wolf was similar to the Grey Wolf but a little larger and slower with a broader head, shorter limbs, wider legs and larger teeth. Live prey included pack-hunted animals such as ancient bison and horses.

The Mastodon was native to North America and is thought to have first appeared almost four million years ago. The animals had course, reddish-brown fur and the average adult stood eight to ten feet tall weighing four to six tons. Compared to elephants, their bodes were long and squat. Compared to mammoths, they were were smaller with stouter skeletons, proportionally larger, flatter skulls and nearly horizontal tusks. While mammoths were grazers, mastodons were browsers of spruce forest and spruce woodland foliage including leaves, twigs, conifer cones, swamp plants, and grasses.