Cordón del Azufre is a small volcanic complex straddling the Chile-Argentina border. The complex consists of a cluster of lava flows from vents on the NE side, wholly within Argentina, and a 5-km-long chain of vents along the border with Chile. An older andesitic-dacitic edifice with a 1.3-km-wide crater was mostly covered by younger Holocene andesitic lava flows. The youngest cone, 300-m-high Volcán la Moyra, was the source of fresh-looking blocky andesitic lava flows that descended 6 km into Chile and 3 km into Argentina.