Abstract This volume contains guides for 33 geological field trips offered in conjunction with the October 2009 GSA Annual Meeting in Portland, Oregon. Showcasing the region’s geological diversity, the peer-reviewed papers included here span topics ranging from accreted terrains and mantle plumes to volcanoes, floods, and vineyard terroir. Locations visited throughout Oregon, Washington, and Idaho encompass Astoria to Zillah. More than just a series of maps, the accompanying descriptions, observations, and conclusions offer new insights to the geologic processes and history of the Pacific Northwest insights that will inspire readers to put their boots on the evidence (or perhaps sip it from a glass of Pinot!) as they develop their own understanding of this remarkable and dynamic corner of the world.

Abstract This trip will cover the terroir (geology, climate, and other natural factors) affecting the quality of Colorado's western slope vineyards and the wines produced. On May 17 the group will make a few key geology overview stops through the Rocky Mountains en route to the wine country on the western slope near Grand Junction. On the western slope the physical factors that allow great wine grapes to be grown in Colorado will be explored and these factors will be compared to other wine viticultural areas in the world. The first day vineyards and wineries will be visited for tasting and discussion of terroir, followed by a banquet dinner and a lecture by Meinert on terroir of some of the other wine regions of the world. The group will spend the night in Grand Junction and on May 18 other wineries will be visited for tasting and terroir discussion; lunch will be at the Canyon Wind winery, with a return to Keystone (and Denver) in the late afternoon. At the end of this chapter, two geological maps (eastern half and western half) show the route of the field trip with trip stops and geological features. These maps are draped on a hillshade of a 90-meter DEM; geological data modified from Green (1992). An 11″×17″-format simplified geological map of Colorado also will be handed out as a reference for the geological transect.

Abstract This trip will cover the terroir (geology, climate, and other natural factors) affecting the quality of Colorado's western slope vineyards and the wines produced. On May 17 the group will make a few key geology overview stops through the Rocky Mountains en route to the wine country on the western slope near Grand Junction. On the western slope the physical factors that allow great wine grapes to be grown in Colorado will be explored and these factors will be compared to other wine viticultural areas in the world. The first day vineyards and wineries will be visited for tasting and discussion of terroir, followed by a banquet dinner and a lecture by Meinert on terroir of some of the other wine regions of the world. The group will spend the night in Grand Junction and on May 18 other wineries will be visited for tasting and terroir discussion; lunch will be at the Canyon Wind winery, with a return to Keystone (and Denver) in the late afternoon. At the end of this chapter, two geological maps (eastern half and western half) show the route of the field trip with trip stops and geological features. These maps are draped on a hillshade of a 90-meter DEM; geological data modified from Green (1992). An 11″×17″-format simplified geological map of Colorado also will be handed out as a reference for the geological transect. The geologic history of Colorado is long and complex. Precambrian metamorphic basement formed prior to ∼1.8 Ga and was intruded by three main Proterozoic granitic suites. The Proterozoic rocks are generally arranged in ENE-trending belts that young to the south and record a history of progressive accretion of terranes onto the Archean Wyoming craton. Following a major erosion event prior to the Late Cambrian, Colorado was a relatively stable craton in the lower to middle Paleozoic as recorded by a thin clastic and carbonate section with local disconformities. Three Phanerozoic orogenic events followed: the Pennsylvanian Ancestral Rocky Mountain (ARM) orogeny, the Late Cretaceous-Late Eocene Laramide orogeny, and the Neogene Rio Grande Rift orogeny. All three events formed generally north-trending fault block uplifts separated by sedimentary basins that cut across the earlier Proterozoic ENE trends. The ARM and Laramide uplifts record crustal shortening whereas the Rio Grande Rift records localized crustal extension. The ARM orogeny was followed by early Mesozoic terrestrial deposition and then state-wide accumulation of thick marine siliciclastic