Caldera Basin

The Caldera Basin is a special place in northern Chile.

It sits along the coast west of Copiapó. The basin lies between the sea and the Chilean Coast Range. It stretches from the port of Caldera to the mouth of the Copiapó River. This area is a sedimentary basin. A sedimentary basin is a place where layers of material build up over time. These layers tell the story of the land and sea.

Many layers of sediment fill this basin. These layers are from the Late Cenozoic age. They rest on top of much older rocks. Some of these are metamorphic rocks from the Paleozoic age. Others are plutonic rocks from the Mesozoic age. The sediment includes things like sand, silt, and clay.

Different layers formed in different ways. The Angostura Formation formed at a high-energy river mouth. The Bahía Inglesa Formation has many parts like the Quebrada Blanca. These parts formed near the shore or on the outer shelf. Some layers might have come from a tsunami. A tsunami is a very large sea wave. The Chorrillos layer may have been made by a debris flow from a tsunami.

Scientists study many specific units in the basin. The Caldera Beds come from the Pleistocene age. The La Higera layer has shale and gypsum veins. It also has sandstone and diatomaceous clay. The Punta Totoral layer shows rapid sea-level changes. The Puerto Viejo layer has sandstone and microcoquina. These names help us know exactly which layer we are looking at.

Learning about this basin helps us see how the Earth changes. We can see how the sea level moves up and down. We can see where rivers used to meet the ocean. The rocks act like a history book for the coast. Each layer of sand or mud is a new page. It shows us how the Chilean coast looked long ago.