The Tres Vírgenes, a line of three connected volcanoes, are west of La Reforma Caldera. They lie along the NE-SW eastern Gulf of California. The three are La Vírgen (The Virgin) in the southwest, El Azufre (Sulfur) in the center, and El Viejo (The Old One) in the northeast. El Viejo is the oldest and lowest peak, and La Vírgen is the youngest and tallest of the three. It has a history of pumice eruptions and explosive eruptions consisting of pyroclastic flows, dacitic and andesitic lava flows.