Mount Baker, the northernmost of Washington's volcanoes, is a 3285-m-high glacier-clad andesitic stratovolcano constructed above the east flank of the eroded mid-Pleistocene Black Buttes volcano and SW of the early Pleistocene 4.5 x 8 km rhyodacitic Kulshan caldera.   With the exception of the Schreibers Meadow cinder cone on the SE flank, which formed about 9800 years ago, Holocene volcanism has been confined to the central conduit.  A major magmatic eruption at Mount Baker about 6500 years ago was the largest eruptive event at the volcano during the Holocene and was accompanied by a major collapse event that produced a lahars down the Nooksack drainage.  Early settlers in the Puget Sound region as far away as Victoria, British Columbia observed 19th-century activity, all of which consisted of relatively minor phreatic eruptions.  Sherman Crater, the historically active crater immediately south of the summit, has been the site of increased steam emission since 1975.