The field features well preserved lava cones, associated with lava flows. The basal basaltic lava flows are interlayered with volcanic debris and more silicic lava flows. To a more recent phase of volcanism belong andesitic centres, some of which lie on river terraces and form easily recognizable coulees. Explosive activity has also left ignimbrites and pumices; such explosive activity took place in the eastern part of the field towards Bazman volcano and was accompanied by the formation of nuee ardente breccia.