- Eastern Europe is a subregion of the European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural, and socio-economic connotations. Its eastern boundary is marked by the Ural Mountains, whilst its western boundary is defined in various ways. Most definitions include the countries of Belarus, Russia, Ukraine, Moldova and Romania while less restrictive definitions may also include some or all of the Balkans, the Baltic states, the Caucasus and the Visegrád group.
- Tukwila Formation—Andesitic to dacitic volcanic sandstone, siltstone, shale, tuff-breccia, tuff, volcanic mudflow (lahar), carbonaceous shales, and minor lava flows or sills. Typically massive; only local sedimentary interbeds indicate structure. K-Ar age on plagioclase from tuff-breccia at top of unit, about 3 km west of quadrangle, yielded an age of 42.0±2.4 Ma (Turner and others, 1983)