[1] The mountain belongs to the Cisne-Morro Negro lava dome, a small volcanic complex near Nevado del Ruiz.

Despite the nevado part of the name, indicating a permanently snow-capped mountain, the summit of El Cisne is now below the permanent snow line as a result of global warming, and it is no longer considered a true nevado.

The complex has well-preserved morphology with barely eroded lava flows, suggesting recent volcanic activity.

The lava flows are andesitic and present notably smaller volumes compared to those observed in neighbouring volcanic complexes (Ruiz and Santa Isabel).

[4] The volcano is located over the Palestina Fault, that crosscuts the underlying El Bosque Batholith of Eocene age, dated at 49.1 ± 1.7 Ma.