Carboniferous and Permian strata of the eastern Klamath terrane, California, include sedimentary and volcanic facies deposited in an island-arc setting. Carboniferous arc volcanism is first recorded in Upper Visean to Namurian portions of the Baird Formation, in which volcaniclastic sediments of marine deltaic origin grade southward to fine-grained, more offshore shelf deposits. During the Westphalian and Stephanian, a volcanic center developed at the southern end of the terrane, and volcaniclastic dispersal aprons of delta-front origin were deposited to the north. Pauses in deltaic progradation are represented by carbonate bank deposits. The Wolfcampian to Lower Leonardian McCloud Limestone represents a period of volcanic quiescence. The McCloud formed as a series of diachronous carbonate platforms that developed on topographic highs of the Carboniferous arc; platforms were bordered by deeper water ramps and escarpments. Renewed arc volcanism in Late Permian time is represented by Lower Guadalupian volcaniclastic sediments of the Nosoni Formation. More proximal volcanic deposition is represented by the overlying Dekkas and Bully Hill formations, with volcanic centers located at the southern end of the terrane. The Carboniferous and Permian sequence of the eastern Klamath terrane resembles Cenozoic deposits of topographically complex intra-arc settings and represents only a small portion of a larger Late Paleozoic island arc.