The Bretz Erratic, a giant rock, plays a minor role in the plot of Ghosts in the Machine, but it doesn’t exist, no—it just seemed like a nice gesture to invent it.
Harlen Bretz taught High School bio in Seattle, and later worked at the University of Washington and the University of Chicago. He was the brilliant, visionary, stubborn geologist who endured decades of ridicule from his peers for insisting that the amazing geology and topography of Eastern Washington’s ‘channeled scablands’ could be explained only by cataclysmic flooding. In an earlier era, no doubt he would have been praised for finding evidence of Noah’s flood; instead the experts said his ideas were preposterous — where could all that water have come from?
The answer wasn’t the wrath of God, but 2,000-foot-deep Lake Missoula. Formed repeatedly by giant ice-dams during a period roughly 15,000 years ago, it emptied every time the ice-dams failed. These “Missoula Floods” happened about twenty times, at intervals of about forty years, sending ice-jammed floodwaters, hundreds of feet deep, racing west and south towards the Columbia gorge. Boulders embedded in remnants of the ice dams were carried hundreds of miles from the other side of the Bitterroot Ranges in present-day Idaho / Montana.
These big glacial ‘erratics’ are dramatic exclamation points in an otherwise empty Eastern Washington landscape. But the largest one in Washington State, and possibly the world, is the Lake Stevens Erratic, pictured (with me) above. It was discovered (or recognized for what it is) only recently, hiding in a scrap of suburban woodland half an hour north of my home in Seattle.