It was declared a nature reserve by Decree 13-20, published in the official newspaper La Gaceta No. 213 of September 9, 1993. It has an area of 4,100 hectares and an elevation of 1,394 meters and a maximum diameter at its base of 24 kilometers . Its last eruption took place more than eight centuries ago and today it is considered extinct; since its crater is now occupied by a small lagoon, which removes the possibility of an igneous reactivation in its interior.
The Maderas is a compound volcano, very old and in an advanced state of erosion and collapse. Large blocks of basalt stand out on its wooded slopes. The volcanic building is cut in its center by a fault oriented from northwest to southeast, clearly delineated between the Balgüe river and the San Pedro cove. The eastern block has moved slightly to the southeast highlighting the presence of two ridges in the volcano's profile, one to the north of 1,127 meters and the other of 1,395 meters next to the lagoon.
In the lower part of the Maderas volcano, between 80 to 450 meters above sea level, we find species of cedar, coyol, strawberry tree, ojoche, ceibo, genízaro, guapinol, guabillo, egg yolk, black wood, pellejo de vieja, guacimillo, guayabón, medlar. mountain, montero avocado, guaba.
