The Colca Canyon - named after the Río Colca flowing at its bottom - represents one of several very deep canyons draining the southern Peruvian Andes towards the Pacific Ocean. Even though it is hard to define the depth of a canyon - and even what is a canyon at all - the Colca Canyon is often considered one of the deepest canyons in the world. It generally follows an east-west direction, characterized by a wide valley with a narrow gorge at the bottom in its eastern (upper) part - also known as Valle del Colca - and a deep, generally V-shaped canyon in its western (lower) part. All this is the result of a complex interplay of various geological and geomorphologic processes, some of which are related to the location of the canyon in the Andean Central Volcanic Zone.
You can descend down to the deepest part of the canyon by clicking in the title image.
Geological evolution of the Colca Canyon
The Colca Canyon can tell us a lot about its geological past - but it only does if the right questions are asked. Thousands of vertical metres of canyon walls give evidence of the changeable history of uplift, incision, and deposition.
Try to tell the history of the Colca Canyon. The photographs in this contribution (you can change the view by clicking on the arrows or in the image) and the transect through the Peruvian Andes can support you. You can also postulate two or more hypotheses.
You can travel through the history of the Colca Canyon by clicking on the arrows.
Imagine a rather flat landscape profile with a shallow river valley. This could have been the situation before the main uplift of the southern Peruvian Andes which started approx. 13 million years (Ma) ago.
This model represents a simplified and distorted representation of reality, which does not claim to be complete or correct. Its purpose is to convey some idea on how the Colca Canyon could have developed.
Active geomorphology in the Colca Canyon
The Colca Canyon is still highly active from a geological and gomorphologic point of view. This can be a challenge for the residents and for local authorities.
Look at the picture! Can you find the landslide?
This landslide below the village of Madrigal is influenced by bank erosion along Río Colca and by seismic activity.
How do you think could this landslide concern the inhabitants of the village?
Landslide processes are a challenge for the residents of the Colca Canyon. This does not only concern those types of slope movements which are fast enough to be life-threatening. Through landslides important cultivation areas or grazing land can be damaged or destroyed. Also irrigation channels, the connection to the river or other parts of infrastructure could be destroyed or cut off. Reconstruction works take time and cost money, and may be damaged in case of reactivation of the landslide. In this specific case, retrogression of the scarp could even threaten the village itself.
Lacroix, P., Berthier, E., & Maquerhua, E. T. (2015). Earthquake-driven acceleration of slow-moving landslides in the Colca valley, Peru, detected from Pléiades images. Remote Sensing of Environment 165: 148-158 [Access source]
Mariño, J., & Macedo, L. (2012). Mapa geológico a escala 1/25,000 del valle del Colca (Arequipa): herramienta para la gestión de riesgos y la planificación del turismo. SlideShare [Access source]
Thouret, J. C., Wörner, G., Gunnell, Y., Singer, B., Zhang, X., & Souriot, T. (2007). Geochronologic and stratigraphic constraints on canyon incision and Miocene uplift of the Central Andes in Peru. Earth and Planetary Science Letters 263(3-4): 151-166 [Access source]
Thouret, J. C., Gunnell, Y., Jicha, B. R., Paquette, J. L., & Braucher, R. (2017). Canyon incision chronology based on ignimbrite stratigraphy and cut-and-fill sediment sequences in SW Peru documents intermittent uplift of the western Central Andes. Geomorphology 298: 1-19 [Access source]
Vasquez Cardeña, S., Peña, F., Sulca, P., Farfán, J., Carpio, J., & Moreno, J. (2012). Características hidrogeológicas del valle del Colca, entre Chivay y Maca [Access source]
This contribution was modified and extended by Martin Mergili.