"It was the biggest flood in the world for which there is geological evidence,"
writes Norman Maclean in A River Runs Through It, referring to the
catastrophic deluge that tore through the Pacific Northwest every time Glacial
Lake Missoula's ice dam gave way. "[I]t was so vast a geological event that the
mind of man could only conceive of it but could not prove it until photographs
could be taken from Earth satellites." Proof now in hand, geologists today
point to numerous features in the landscape that reveal the extreme scale and
violence involved in these truly colossal floods. In this interactive map of
the vast region affected, both within the storied Channeled Scabland and
beyond, take a look at some of these telling features. To launch the
interactive, click on the image at left.—Peter Tyson
