The Nova Iguaçu Volcano ("Vulcão de Nova Iguaçu" in Portuguese) is located in the state of Rio de Janeiro, Brazil, in an area of volcanic rocks at the north-eastern border of the Mendanha massif. Klein and Vieira proposed the site to be an extinct volcano with a volcanic cone, volcanic crater, and volcanic bomb. Scientific journals have studied the volcanic geology of the area, identifying the rocks of volcanic appearance as constituted of subvolcanic intrusive rock bodies. The Nova Iguaçu volcano theory is now extinct in academic communities, but the myth continues in sightseeing promotion groups. Recent research revealed that volcanic eruptions did occur in the Nova Iguaçu region. After the eruptions, an intense uplifting and consequent regional denudation took place. The cones, craters, lavas, pyroclastic flow deposits, and volcanic bombs have been washed away in the strong tropical erosion of this region, exposing the underlying geologic structure. The Municipal Park is underlain by the geologic bodies corresponding to the magma chamber (composed of syenite and trachyte) and subvolcanic conduit (made up of pyroclastic rocks) of a depth of 3 kilometers, such as pyroclastic dikes. That is, no extinct volcano is present at Nova Iguaçu. The outcrops are world-rare geological phenomena that expose the underground geologic structures of the volcanic area. Locality The debated volcano is in the Municipality of Nova Iguaçu, about 35 kilometers to the west-northwest of Rio de Janeiro, Brazil. It is a horseshoe-shaped valley opening to the north at the north-east flank of the Mendanha massif, about 2 kilometers south-southeast of the Nova Iguaçu railway station. It is 800 meters long, 700 meters wide, and 180 meters deep at . This area is surrounded by peaks more than 400 meters high, such as Contenda Rock, Austral Rock, Confeito Rock, and Contento Peak, which are underlain by pyroclastic rock. This rock originated from rock fragments created by a volcanic explosion. The valley is made up of trachyte, another igneous rock with massive texture. The pyroclastic rock was the main justification of the Nova Iguaçu Volcano hypothesis. Proposal of the volcano hypothesis The existence of a volcano at Nova Iguaçu was proposed by geologists Viktor Carvalho Klein and André Calixto Vieira in the 1980s. Klein and Vieira based their discovery on the presence of pyroclastic rocks (including volcanic bombs) and the existence of a volcanic crater. They believed the pyroclastic rock to be pyroclastic flow deposits, constituting an