Abstract A broad spectrum of geological and geophysical information has recently been collected within the Amlia corridor (173°W longitude) of the Aleutian Ridge. The ridge’s upper crustal rocks can be divided into three rock series: lower, middle, and upper. The Aleutian Ridge is fundamentally a massive, little deformed antiform of lower series rocks produced by voluminous submarine volcanism in Eocene and perhaps earlier Tertiary time. Erosional debris from the dying arc accumulated over its flanks as the middle and upper series deposits of Oligocene through Holocene age; these deposits are as much as 4 to 5 km thick. A slightly deformed mass of tectonically thickened trench deposits underlies the lower part of the trench’s landward slope. This accretionary wedge was added in post-middle Miocene time to the ridge’s igneous framework of lower series rocks.