Exploring the Science and Beauty of Sand
Itaipuaçu Beach, Maricá, State of Rio de Janeiro, Brazil
Maricá is located 20 miles east of the metropolitan area of the city of Rio de Janeiro. Itaipuaçu Beach is among the famous beaches along Brazil’s Atlantic coast.
Sugarloaf Mountain overlooks and forms the backdrop of Rio. This mountain is an example of the granitic Pre-Cambrian continental basement rock under eastern South America, part of the Serra do Mar range that runs parallel to the Atlantic Ocean. Tectonically, these mountains are very stable. However, over tens of millions of years, the mountains have eroded, and the rock has weathered to the medium, coarse quartz and feldspar grains in this sand. Feldspar grains show close to a 90° corner while the quartz grains are rounder.
These grains are well rounded and polished, an indication of high wave energy. On this west-east trending shoreline, waves are generated by easterly trade winds and are accompanied by southerly swells arriving from the South Atlantic.
CIA (public domain via Wikimedia Commons)
Anna Beatriz Fonseca. CC BY-SA 3.0