Serra dos Orgaos

Serra dos Orgaos is a mountain range in Rio de Janeiro state, Brazil, forming an escarpment on the northern edge of the Guanabara Graben between the towns of Petropolis and Teresopolis and covering about 20,024 hectares. It is built of granitic gneiss dating to the Neoproterozoic era, roughly 620 million years old, shaped by faulting and erosion; its most distinctive peaks, including Dedo de Deus, or God's Finger, at 1,692 meters, stand on a thick dike of more erosion-resistant Cambrian granite. Elevation across the range runs from near sea level to 2,263 meters at its highest point, Pedra do Sino, over a horizontal distance of only about four kilometers, and the peaks are visible from Rio de Janeiro itself, some 50 kilometers away. The range's name, meaning organ range, comes from the resemblance of its vertical rock formations to the pipes of a church organ; it is unrelated to The Organ Pipes, a separate basalt column formation already documented on this atlas in Victoria, Australia. This entity documents Serra dos Orgaos specifically as a geological formation, a Neoproterozoic gneiss escarpment on the Guanabara Graben with Cambrian-granite-cored peaks.