Columbia River Basalt Group
- Carton (Wikipedia)
A craton ( /ˈkreɪtɒn/ KRAYT-on, /ˈkrætɒn/ KRAT-on, or /ˈkreɪtən/ KRAY-tən; from Ancient Greek: κράτος kratos “strength”) is an old and stable part of continental lithosphere (the Earth’s two topmost layers, the crust and the lithospheric mantle). Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates; the exceptions occur where geologically recent rifting events have separated cratons and created passive margins along their edges. Cratons are composed of ancient crystalline basement rocks covered by younger sedimentary rocks. They have a thick crust and deep lithospheric roots extending several hundred kilometres into Earth’s mantle. In simpler terms, craton is a layer of the earths crust on that has been almost unchanged through all of history. This crust consists of shields and platforms. Shields are made of basement rock and are visible, while platforms is the portion not visible made up of sedimentary rock.
- John Day River (Wikipedia)
The John Day River is a tributary of the Columbia River, approximately 284 miles (457 km) long, in northeastern Oregon in the United States. It is known as the Mah-Hah River by the Cayuse people. Undammed along its entire length, the river is the fourth longest free-flowing river in the contiguous United States. There is extensive use of its waters for irrigation. Its course furnishes habitat for diverse species, including wild steelhead and Chinook salmon runs. However, the steelhead populations are under federal Endangered Species Act (ESA) protections, and the Chinook salmon have been proposed for such protection.
Columbia River Basalt Group map shows main regions of basalt exposure in Washington, Oregon, Idaho and Nevada, USA. (usgs.gov)