THE COTAHUASI CANYON.

The Cotahuasi Canyon near the city of Arequipa in Peru is the deepest canyon in the world. It is an impressive chasm that the River has eroded between two enormous mountain massifs: the Coropuna and the Solimana. One extends from spurs of the snow-covered Solimana to the confluence with the Ocona River. The Canyon was cut by the Cotahuasi River, a tributary of the Rio Ocona, to a depth of approximately 3,354m.
Coropuna is a dormant volcano in the Southern Andes, 155km/96mi from Arequipa and belongs to the Central Volcanic Zone that extends from Peru to Chile and forms the western boundary of the Andean Plateau. Its summit reaches an altitude of 6,377m/20,922ft above sea level. It has been active for at least 5 million years, with the bulk of the current cone having formed during the Pilocene-Pleistocene in the geological time-scale that extends from 5.333 million to 2.58 million years ago. The thick ice cap that covers the volcano, 2nd largest in the tropics, has undergone several phases of expansion and reduction. As of 2016, the ice cap is in retreat and it will disappear by 2045, threatening the water supply of ten thousands of people. The interaction between volcanic activity and glacial effects has generated mud flows that could be a hazard to surrounding populations if the mountain returns to volcanic activity.
The mountain was considered sacred by the Inca, and a number of archaeological sites have been discovered there. The Inca built the highest irrigation system in the world on the Coropuna.
Solimana is a volcanic massif about 6,093m/19,990ft above sea level. It lies North West of Coropuna.
The Cotahuasi Canyon is formed by the Cotahuasi River, arising at more than 4,750m/15,580ft above sea level in the Lake Wansuqucha. It receives the tributaries of the Wayllapana River in the neighboring Pampamarka to the North, and the Huarcaya near Tumipampa to the West, and is later joined by the Maran River to form the Ocona River (Chaucalla Village) that ends at the Pacific Ocean.
Cotahuasi Province is located at the highest Andean point of Arequipa. It is characterized by its steep relief: incised by rivers and gullies, ranging between 1,000 and 6093 meters, with 19 ecological zones.
The altitude and remoteness of this region has contributed that its residents have retained many of the practices that are now no longer common in neighboring regions. The only road leading to the Canyon goes through Chuquibamba in the Condesuyos Province, then Aplao in Castilla Province. It begins on the Panamerican Highway near Arequipa. The drive is 10-12 hours long on a road which is unpaved after Chuquibamba. It also goes quite high, through a 4,500m pass between Coropuna and Solimana.
The difficult topographic conditions have generated specific landscapes like agricultural terraces. The landscapes are quite many, from the rivers at the bottom of the Canyon to the cold desert areas of the summits. It produces kiwicha, quinoa, mint, purple corn, llacon, fava, oca, beans, arveja, chulpi maize, anise, tarwi. Medicinal plants like muna, retama, tara, coca, jara (malva sylvestris), ruda, yareta.  These products are meant to give priority to food supplies to the province, therefore, very little is produced for export. ood autonomy is reached thanks to ancient techniques, rational use of water, promotion of improved seeds, conservation of bio-diversity and complementary livestock breeding.
There are also a number of Inca and pre-Inca works including many agricultural terraces still in use today.