From Fire Mountains of the West, by Stephen L. Harris:

"When he published the first geological reconnaissance of the Three Sisters region in 1925, E.T. Hodge concluded that these mountains were but remnants of a once vastly larger volcanic cone that had collapsed in Miocene or early Pliocene time. The broad arc of peaks that runs from Broken Top through Devil's Hill, the Wife and Sphinx, Husband, Little Brother, and North Sister seemed to outline an ancient caldera rim. Observing the long slopes leading outward from the ragged arc, one might easily imagine them projected upward to an enormous central cone. Hodge called this theoretical ancestor of the Sisters Mount Multnomah. He concluded that it had been engulfed, in much the same way that ancient Mazama had collapsed to form the caldera in which Crater Lake lies.

"In the 1940's the late Howel Williams, then dean of Cascade volcanologists, examined the Three Sisters and associated peaks. He concluded that each of the edifices in question is a totally separate volcano. While several cones may be parasitic to the larger peaks, none represents survivors of a demolished older structure. Mount Multnomah never existed!"

Harris, Stephen. 1988. Fire Mountains of the West: The Cascade and Mono Lake Volcanoes. Missoula, Montana: Mountain Press.

©D.L. Mark 1997