Eduardo Cesar
Preserved in a park in Itu, rocks with light and dark layers once formed the bottom of a lake near a glacier 270 million years agoEduardo CesarA list of 142 geological sites in 81 municipalities in the state of São Paulo, organized by a group of 30 experts from universities, research institutes and businesses, has begun to circulate. The purpose of the endeavor is to encourage site preservation. In 2012, with that goal in mind, the Brazilian Commission on Geological and Paleobiological Sites (SIGEP) introduced a national inventory of 116 sites of geological importance, 16 of which are in the state of São Paulo.
The new inventory covers a region that contains vestiges of 16th– and 17th–century gold exploration in a forest on the outskirts of the municipality of Guarulhos, in the São Paulo Metropolitan Area. “This spot had a vein of quartz that the gold was associated with,” notes geologist Edson Barros of the Guarulhos city government, pointing to the bottom of a recess. Stone walls in the midst of the forest and water drainage tunnels are some of the other remnants of the first gold mines opened by the Portuguese in Brazil in the late 16th century, 100 years before mining began in the state of Minas Gerais.
These sites, or geosites, described in an article published in January 2017 in the journal Geoheritage, are scientifically important places. “They should be conserved by the responsible bodies in order to preserve the state’s geological history,” says geologist Maria da Glória Motta Garcia, a professor at the Geosciences Institute of the University of São Paulo (IGc-USP) and coordinator of the study. “In Europe, inventories of this type have served as the basis for the creation or adaptation of laws to protect the geological heritage.” Geologist José Brilha, a professor at Portugal’s University of Minho and co-author of the inventory, coordinated a similar inventory of 320 geosites in Portugal that was completed in 2010.
On the basis of their scientific value and conservation policies, seven geosites have now been recognized by the São Paulo State government as state geological monuments and are open to visitors. Geological monuments are geosites of impressive beauty or cultural importance, such as Corcovado Mountain in the city of Rio de Janeiro, or Iguaçu Falls in the state of Paraná. Rocks scarred by 260-million-year-old glaciers are conserved in two parks in the municipalities of Itu and Salto. Devil’s Hill, with its sandstone deposits that were formed about 80 million years ago, is located in a state park in the municipality of Teodoro Sampaio, 660 kilometers from the state capital.
But other sites are quite vulnerable, such as the rocks containing ichnofossils—fossilized tracks—in the municipality of Rosana, which are at risk of decomposing due to changes in the water level arising from the operation of the Porto Primavera Power Plant. “The ichnofossils at Porto Primavera are embedded in ancient sand deposits in the interior of a great desert that existed there between 90 million and 65 million years ago,” says geologist Luiz Fernandes, a professor at the Federal University of Paraná who participated in the inventory.
Geographer Rogério Rodrigues, technical director of the Geological Monuments Center at the Geological Institute of São Paulo, suggests that “the teams from municipal governments and the owners of land that hosts geosites should first adopt safety and conservation measures by installing fencing, entrances and infrastructure for visitors before they look into the tourism potential of those places.”
“In Brazil, there are no specific laws governing the preservation of geological heritage or geodiversity,” says geologist Gustavo Beuttenmuller of the São Paulo Municipal Department of Green Areas and the Environment. Nonetheless, there has been some progress. According to geologist Oswaldo Landgraf Júnior, also from the Department of Green Areas, the city is planning to expand the Colônia Crater municipal park in São Paulo’s Parelheiros district, which was established in 2007 to protect the slopes and interior of a hollow created by the impact of a celestial body about 35 million years ago. Barros, along with his team and other groups, is working to preserve and provide some visibility for the geological structures and buildings associated with mining in Guarulhos.
The past etched into the rocks
Geosites represent the geological history of the state of São Paulo
