Remnants of Continental Drift in “Carioca” Landscape

July 16, 2013


Photographer: Mario Freitas
Summary Author: Mario Freitas

Shown above is an unusual perspective of the celebrated monolith known as Sugar Loaf in Rio de Janeiro, Brazil. It can be seen in the foreground, rising 1,299 ft (396 m) above sea level. Sugar Loaf is composed of augen gneiss metamorphic rock, and dates from the epoch when the Gondwana continent was formed (560 million years ago). This well know mountain and others nearby stand above the eroded landscape because of their high hardness and resistance to weathering. Note that augen gneiss can split smoothly along the cleavage planes of its component minerals. These properties allow its use in architectural detailing of most of the historical churches and palaces of the so-called “Marvellous City.”

I took this photo a few seconds after leaving Santos Dumont Airport near Rio. In addition to Sugar Loaf, we can observe segments of the Atlantic rainforest, gorgeous sand beaches as Copacabana (left side) and Corcovado Mountain, also composed by augen gneiss (far right background) and having at its summit the largest Art Deco style sculpture in the world, “Christ the Redeemer”. Charles Darwin visited Rio de Janeiro in 1832 and wrote in his journal A Naturalist Voyage Around the World: “Nothing can be more striking than the effect of these huge rounded masses of naked rock rising out of the most luxuriant vegetation.” Picture taken on May 27, 2013.

Photo Details: Camera Maker: Panasonic; Camera Model: DMC-LX5; Focal Length: 6.8mm (35mm equivalent: 32mm); Aperture: f/2.8; Exposure Time: 0.0080 s (1/125); ISO equiv: 80.