Richard B Waitt, PhD

In late Wisconsin time, the Purcell Trench lobe of the Cordilleran ice sheet dammed the Clark Fork of the Columbia River in western Montana, creating glacial Lake Missoula. During part of this epoch, the Okanogan lobe also dammed the Columbia River downstream, creating glacial Lake Columbia in northeast Washington. Repeated failure of the Purcell Trench ice dam released glacial Lake Missoula, caus

The Channeled Scabland of eastern Washington State, USA, brought megafloods to the scientific forefront. A 30,000-km2 landscape of coulees and cataracts carved into the region’s loess-covered basalt attests to overwhelming volumes of energetic water. The scarred landscape, garnished by huge boulder bars and far-travelled ice-rafted erratics, spurred J Harlen Bretz’s vigorously disputed flood hypot

This field guide explores volcanic effusions, sediments, and landforms at Mount St. Helens in Washington. A detailed synopsis outlines the eruptive history of Mount St. Helens from about 300,000 years ago through 1980 and beyond.The five days in the field include about 28 stops and 12 potential stops. Exposures in valleys surrounding Mount St. Helens reveal records of diverse Pleistocene and Holoc

The late Wisconsin Icicle Creek alpine glacier transported tonalite boulders from the Mount Stuart batholith to arcuate end moraines in Icicle valley and Wenatchee valley near Leavenworth. Some previous workers considered sparsely weathered Mount Stuart boulders lying outside these moraines and draped by silt as having been ice rafted in a late Wisconsin lake. But the boulders are more likely with

The Methow, Chelan, Wenatchee, and other terrane blocks accreted in late Mesozoic to Eocene times. Methow valley is excavated in an exotic terrane of folded Mesozoic sedimentary and volcanic rocks faulted between crystalline blocks. Repeated floods of Columbia River Basalt about 16 Ma drowned a backarc basin to the southeast. Cirques, aretes, and U-shaped hanging troughs brand the Methow, Skagit,

Immense late Wisconsin floods from glacial Lake Missoula drowned the Wenatchee reach of Washington's Columbia valley by different routes. The earliest debacles, nearly 19,000 cal yr BP, raged 335 m deep down the Columbia and built high Pangborn bar at Wenatchee. As advancing ice blocked the northwest of Columbia valley, several giant floods descended Moses Coulee and backflooded up the Columbia pa

A lahar is a flowing slurry of rock debris and water originating on the slopes of a volcano. The term may also mean the deposit of such a flow.

A geologist with intimate knowledge of Mount St. Helens, Richard Waitt chronicles the eruption through unforgettable, riveting narratives—the heart of a masterful chronology that also delivers engrossing science, history, and journalism.

An icy volcano even if called extinct or dormant may be active at depth. Magma creeps up, crystallizes, releases gas. After decades or millennia the pressure from magmatic gas exceeds the resistance of overlying rock and the volcano erupts. Repeated eruptions build a cone that pokes one or two kilometers or more above its surroundings - a point of cool climate supporting glaciers. Ice-clad volcani

Augustine Island (volcano) in lower Cook Inlet, Alaska, has erupted repeatedly in late-Holocene and historical times. Eruptions typically beget high-energy volcanic processes. Most notable are bouldery debris avalanches containing immense angular clasts shed from summit domes. Coarse deposits of these avalanches form much of Augustine's lower flanks. This geologic map at 1:25,000 scale depicts the

A late Wisconsin volcano erupted onto the JurassicCretaceous sedimentary bedrock of Augustine Island in lower Cook Inlet in Alaska. Olivine basalt interacting with water erupted explosively. Rhyolitic eruptive debris then swept down the south volcano flank while late Wisconsin glaciers from mountains on western mainland surrounded the island. Early to middle Holocene deposits probably erupted onto

Augustine Island (volcano) in lower Cook Inlet, Alaska, has erupted repeatedly in late-Holocene and historical times. Eruptions typically beget high-energy volcanic processes. Most notable are bouldery debris avalanches containing immense angular clasts shed from summit domes. Coarse deposits of these avalanches form much of Augustine's lower flanks. A new geologic map at 1:25,000 scale depicts th