Indian Heaven consists of several, overlapping shield volcanoes that run along a line from Sawtooth Mountain at the north to Red Mountain to the south, as well as cinder cones, lava flows, and spatter cones (low, steep-sided hills or mounds that consist of welded lava fragments). With a total magma output of , the field has about 50 mafic eruptive edifices (rich in magnesium and iron),[a] whose activity lasted from the Pleistocene to the early Holocene. Roughly half of these vents mark a mountainous highland, in length, which runs parallel to the north-south trend of the Cascade Arc in southern Washington state.