Columbia River Basalt Group Stretches from Oregon to Idaho (usgs.gov)
The corresponding Wikipedia article incorporates public domain material from this USGS article.
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The thick, layered lava flows of the CRBG erupted as flood basalts, which originate as some of the most highly effusive eruptions in the world. The CRBG sequence a classic example of flood basalt activity that erupted more than 350 lava flows from about 16.7 Ma to 5.5 Ma. The eruptions originated from a series of generally north-northwest-trending linear fissures, ranging from tens to hundreds of kilometers in length, located along the Washington/Oregon/Idaho border. The magma that fed these massive eruptions may have come from a plume-like upwelling from the mantle called a hot spot. Since the time of the CRBG eruptions, the North American plate has moved in a west-southwestwardly motion, and that hot spot is now believed to reside beneath Yellowstone volcano in northwest Wyoming.
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Phalaris arundinacea L. (plants.sc.egov.usda.gov)Reed canarygrass is 2-9 feet tall non-native with flat, rough-textured, tapering leaves from 31/2-10 inches long. The stem is hairless and stands erect. One of the first grasses to sprout in the spring, reed canary grass produces a compact panicle 3-16 inches long that is erect or slightly spreading. The flowers are green to purple early in the season and change to beige over time. The grass forms a thick rhizome system that quickly dominates the soil. There is some debate as to the origin of the species. Sources document native and non-native genotypes of reed canary grass. The non-native strain is thought to be more invasive than native strain.
