Abstract McNary Lock and Dam is located on the Columbia River in Oregon and Washington about 292 miles above the river mouth. The dam is approximately 7500 feet long with a maximum headwater to tail water of 92 feet. Following the current economic principles of construction, McNary Dam is built of two types of material. The powerhouse, spillway, nonoverflow, and navigation lock are constructed of concrete, while the connections to the abutments are constructed of soil materials. Both the concrete structures and the earth embankments are founded on basalt or basaltic flow breccia rock. The plan of the dam is shown in Figure 1. Foundation Treatment for Earth Dams on Rock, by Mr. Thomas F. Thompson, published by the American Society of Civil Engineers, volume 80, Separate no. 548, describes detailed foundation procedures and cites several of the foundation problems at McNary Dam. Geological Features at McNary Dam, by Mr. Charles J. Monahan, describes the layout of the dam and the geologic features of the dam site.

Abstract The McNary dam is a combination embankment-concrete spillway dam on the Columbia River in the Umatilla Basin, 300 miles from the ocean. The concrete part of the dam rests upon a nearly flat-lying massive basalt which in turn lies above a sedimentary layer 40-60 feet thick. The embankment rests upon two terrace deposits which overlie the lava. These sediments are protected by a blanket of impervious material. The underlying lava was scoured to a depth of 5 feet by water flowing 25 miles an hour while the water was being diverted in the course of construction and up to 50 feet by water moving with a maximum velocity of 32.4 miles an hour. These velocities are greater than the anticipated maximum velocity after the dam is completed. The underlying lava was broken by two faults. One, a small fault, was cleaned out and backfilled with a few feet of concrete. The other, a large fault with gentle dip and gouge several feet thick, was cleaned out and back filled with cement to a point sufficiently far below the surface of the overlying bedrock to make a firm foundation.

Abstract Prepared for the Division on Engineering Geology of the Geological Society of America, Engineering Case Histories 1 includes 9 case histories ranging from the geology of the Queens Midtown Tunnel to the McNary Dam, Oregon.

ABSTRACT Emplacement models for voluminous sheet flows of the Columbia River flood basalts vary significantly in style and duration, with the latter ranging from as little as one week to decades and even centuries. Testing the efficacy of such models requires detailed field studies and close examination of each stratigraphic unit. The Steens Basalt, the oldest formation of the Columbia River flood basalts, differs from the later formations in that it is composed of stacked successions of thin, commonly inflated flow lobes combined into thicker compound flows, or flow fields. These flow lobes are of limited geographic extent, with relatively high emplacement rates, but they are otherwise similar to modern examples. Evidence for flow inflation in the much larger sheet flows of the Grande Ronde Basalt, Wanapum Basalt, and Saddle Mountains Basalt is also apparent, but with more variable rates of emplacement. For example, the Asotin and Umatilla Members (Saddle Mountains Basalt) and Sentinel Bluffs Member flows (Grande Ronde Basalt) erupted distinct compositions along their linear vent systems, but over 200 km west of their vents, these flows are no longer distinct. Instead, they exist as compositional zones of a single, moderately mixed lava flow. Such flows must have been emplaced rapidly, in perhaps weeks to months, while others have been shown to erupt over much longer time periods. We conclude that emplacement rates may be quite variable throughout the Columbia River flood basalt province, with thin flow units of Steens Basalt erupting continuously and rapidly, and larger inflated sheet flows erupting over variable time spans, some from a few weeks to months, and others over a duration of years.

Abstract The Columbia River empties into the Pacific Ocean near latitude 46° N. Much of the detrital load of the river is distributed over a 165 km long littoral cell between Tillamook Head, Oregon, and Point Grenville, Washington. The cell is characterized by north-directed littoral drift in response to dominant southwest winter storms, yet it experiences a summer drift reversal in response to more modest northwest winds and seas. The result has been development of extensive barrier beaches during the late Holocene, which define the major embayments of Willapa Bay and Grays Harbor. The mouth of the Columbia River was modified by jetties beginning late in the nineteenth century. The entrance to Grays Harbor has been jettied since early in the twentieth century. This article discusses changes resulting from these modifications. Dams on the Columbia River and its tributaries built during the twentieth century appear to have significantly reduced the detrital load available to the littoral cell, resulting in the onset of changes in the deposition-erosion regimen.

Abstract Geoarchaeological research in the mid-Columbia region of central Washington over the past 10 yr has produced new information regarding Paleo-Indian archaeology and environmental change in the inland Northwest. Stratigraphic, sedimentological, and geomorphic studies provide important contextual information for locating and interpreting Washington’s earliest archaeological sites and human remains. Recent discoveries increasingly point toward human occupation of the region during a time of post-glacial warming and reduced effective moisture 11,200–9000 14 C yr B.P. This field guide presents recent research focusing on geoarchaeological studies at the Kennewick Man discovery site, at latest Pleistocene relict Channeled Scabland marsh sites, and at the recently excavated Sentinel Gap Paleo-Indian site.

Abstract Washington State is second only to California in terms of wine produced in the United States, and some of its vineyards and wines are among the world’s best. Most Washington vineyards are situated east of the Cascades on soils formed from Quaternary sediments that overlie Miocene basaltic rocks of the Columbia River Flood Basalt Province. Pleistocene fluvial sediments were deposited during cataclysmic glacial outburst floods that formed the spectacular Channeled Scabland. Late Pleistocene and Holocene sand sheets and loess form a variable mantle over outburst sediments. Rainfall for wine grape production ranges from ~6-18 in (150-450 mm) annually with a pronounced winter maximum and warm, dry summers. This field trip will examine the terroir of some of Washington’s best vineyards. Terroir involves the complex interplay of climate, soil, geology, and other physical factors that influence the character and quality of wine. These factors underpin the substantial contribution of good viticultural practice and expert winemaking. We will travel by bus over the Cascade Mountains to the Yakima Valley appellation to see the effects of rain shadow, bedrock variation, sediment and soil characteristics, and air drainage on vineyard siting; we will visit the Red Mountain appellation to examine sites with warm mesoclimate and soils from back-eddy glacial flood and eolian sediments; the next stop will be the Walla Walla Valley appellation with excellent exposures of glacial slackwater sediments (which underlie the best vineyards) as well as the United States’ largest wind energy facility. Finally, we will visit the very creatively sited Wallula Vineyard in the Columbia Valley appellation overlooking the Columbia River before returning to Seattle.