Seen above are the remains an ancient mountain range and one of the oldest rock formations on Earth known as the Tandilia System, named for the nearby town of Tanadil. Photographer: Luis Argerich – Luis’s web site
The system stretches approximately 215 mi (350 km) across the Argentine province of Buenos Aires from Olavarria southeast to Cape Corrientes where it enters the Atlantic Ocean between the cities of Mar del Plata and Miramar. The system is built on two billion year old igneous and metamorphic rock that most likely was a part of the supercontinent Rodinia when its coasts were uplifted during the Paleoproterozoic Era. Over a period of hundreds of millions of years, layers of stratified sediments built up on this base. Many of these sediments, particularly those from the Lower Ordovician, consist of quartz arenite and claystones containing an abundance of fossils and offer insights into life on Earth after the Cambrian–Ordovician extinction event of 488 million years ago. Small hills about 1640 ft (500 m) high are all that remain of this once mighty mountain range.