Many events, peoples, and places make up the geological, cultural, economic, social and political history of our region – from the mouth of the river down the Gorge to well into the high desert country. Below is a chronology that helps to give basic introductory to some of the highlights of our past.
Circa 30,000 BC – 1,000 AD.
Precursor: A time of natural upheaval creates the Columbia River Gorge. Beginning around 35,000,000 years ago, volcanic eruptions spew hundreds of feet of basalt to create the Columbia basin of present-day Oregon and Washington. Over time, flooding begins to etch the Columbia Gorge. By 30,000 BC a large ice sheet, expanding and contracting as warming and cooling periods – each lasting for thousands of years at a time – come and go.
ca. 30,000 – 15,000 BC – The continental ice sheet which extends to the upper reaches of what is now Washington state and also into the upper portions of other current Western states such as Idaho and Montana, begins to recede slightly due to another warming period.
A southerly arm of the continental ice mass dams a portion of ice-melt in what is now northwestern Montana. A massive lake, known by geologists as the Missoula Glacial Lake, forms behind this dam and reaches up to 2,000 feet in depth and larger than the contemporary mid-western “Great Lakes” of Lake Erie and Lake Ontario combined.
The ice-dam fails around forty times over at least two or three thousand years causing massive and rapid flooding of present-day eastern Oregon and Washington and into what is now the Willamette Valley. The latter area is strewn not only with boulders carried by the flood waters from far off Montana and Idaho but rich silt is deposited in the valley – but one cause of the area’s agricultural fertility in more recent epochs.
Oral traditions of the Wasco people, who claim to have lived in the area of the Columbia Corridor since “before the river flowed,” attach a volcanic cause to the repeated failure of the Montana ice dam. Modern-day geologists attribute the failures to various causes that include warmer temperatures from time to time and to the erosive effect of the water being held in check within the inland lake.
The floods are massive and in addition to their transformation of the region as a whole also further scour the Columbia Gorge and create an ever deeper thoroughfare through which the river flows. Flood waters reach a speed of close to seventy miles an hour and heights of over a thousand feet at times with waters nearly as high as 600 feet at what is now Vista House.
Between 15,000 BC and 10,000 BC, the draining and filling of the great Missoula inland lake peters out and the scouring powers of massive floods come to an end. The Columbia River Gorge assumes roughly the course, appearance, and shape, as we know it presently.