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 The Yellowstone Geoecosystem ( Smith and Siegel, 2000 ; Morgan, 2007 ) comprises an amazing diversity of geologic features that control the character and distribution of geothermal features and soils of this landscape. The underlying bedrock geology of Yellowstone National Park (YNP) includes: Precambrian basement along the northern margin of the Park, with both low-grade metasedimentary rocks (biotite-andalusite-staurolite schists, quartzites and banded iron formations) and late Archean granitoid rocks. Phanerozoic sedimentary rocks in the northwestern corner of the Park in the southern Gallatin Range, that includes notably the Mississippian Madison Limestone near Mammoth Hot Springs, and Cretaceous shales and sandstones of the Kootenai, Eagle, Frontier and Harebell formations, south of Gardiner. The voluminous Eocene Absaroka Volcanics dominantly consisting of andesitic flows, tuffs, volcaniclastic rocks and hypabyssal intrusions. The iconic caldera-forming eruptive rocks of the Tertiary Huckleberry Ridge Tuff (2.1 Ma), Mesa Falls Tuff (1.2 Ma), and Lava Creek Tuff (0.61 Ma) of dominantly rhyolitic composition, and the post-caldera rhyolites (Christansen, 2001). The surficial geology of YNP ( Good and Pierce, 1996 ) additionally involves complex interactions of glacial geology ( Pierce, 1979 ) and active tectonics ( Pierce et al., 2007 ; Smith references). Tertiary volcanism and associated hydrothermal activity are directly related to the elevated hot spot that formed the regional Snake River Plain-Yellowstone system ( Smith and Siegel, 2000 ). Yellowstone contains the greatest number and diversity of geothermal systems on the planet, yielding an extensive array of extreme high-temperature environments, many of which are colonized by microorganisms that play either

Abstract In central Idaho, Neoproterozoic stratified rocks are engulfed by the Late Cretaceous Idaho batholith and by Eocene volcanic and plutonic rocks of the Challis event. Studied sections in the Gospel Peaks and Big Creek areas of west-central Idaho are in roof pendants of the Idaho batholith. A drill core section studied from near Challis, east-central Idaho, lies beneath the Challis Volcanic Group and is not exposed at the surface. Metamorphic and deformational overprinting, as well as widespread dismembering by the younger igneous rocks, conceals many primary details. Despite this, these rocks provide important links for regional correlations and have produced critical geochronological data for two Neoproterozoic glacial periods in the North American Cordillera. At the base of the section, the more than 700-m-thick Edwardsburg Formation (Fm.) contains interlayered diamictite and volcanic rocks. There are two diamictite-bearing members in the Edwardsburg Fm. that are closely related in time. Each of the diamictites is associated with intermediate composition tuff or flow rocks and the diamictites are separated by mafic volcanic rocks. SHRIMP U–Pb dating indicates that the lower diamictite is about 685±7 Ma, whereas the upper diamictite is 684±4 Ma. The diamictite units are part of a cycle of rocks from coarse clastic, to fine clastic, to carbonate rocks that, by correlation to better preserved sections, are thought to record an older Cryogenian glacial to interglacial period in the northern US Cordillera. The more than 75-m-thick diamictite of Daugherty Gulch is dated at 664±6 Ma. This unit is preserved only in drill core and the palaeoenvironmental interpretation and local stratigraphic relations are non-unique. Thus, the date for this diamictite may provide a date for a newly recognized glaciogenic horizon or may be a minimum age for the diamictite in the Edwardsburg Fm. The c . 1000-m-thick Moores Lake Fm. is an amphibolite facies diamictite in which glacial features have not been observed. However, it is part of a sedimentary cycle from unsorted siliclastic deposits to mud and carbonate deposits. Using lithostratigraphy and available geochronology, the Moores Lake Fm. is correlated with a younger succession of Cryogenian glaciogenic rocks in southeastern Idaho. Traditional correlations of Neoproterozoic rocks in the Cordillera recognize two levels of Cryogenian diamictites. The Edwardsburg and Moores Lake diamictites along the middle Cordillera fit well into the scenario of two glacial events. Because of the correlations, dates that provide ages for the diamictites in central Idaho (and corroborated in southeastern Idaho, Link & Fanning 2008 ) could constrain the age of correlated glaciogenic deposits elsewhere in the Cordillera. However, in the absence of dates for the glaciogenic diamictites in Canadian and southern US Cordilleran sections, the correlations are considered possible but uncertain.