Research beginning in the late 1990s shows that Mount Baker is the youngest of several volcanic centers in the area and one of the youngest volcanoes in the Cascade Range. The Pliocene Hannegan caldera is preserved northeast of Mount Baker Volcanic activity in the Mount Baker volcanic field began more than one million years ago, but many of the earliest lava and tephra deposits have been removed by glacial erosion. The pale-colored rocks northeast of the modern volcano mark the site of the ancient (1.15 million years old) Kulshan caldera that collapsed after an enormous ash eruption one million years ago. Subsequently, eruptions in the Mount Baker area have produced cones and lava flows of andesite, the rock that constitutes much of other Cascade Range volcanoes such as Rainier, Adams, and Hood. From about 900,000 years ago to the present, numerous andesitic volcanic centers in the area have come and disappeared through glacial erosion. The largest of these cones is the Black Buttes edifice, active between 500,000 and 300,000 years ago and formerly bigger than today's Mount Baker.