GeoLog

Imaggeo on Mondays: Erosion

Imaggeo on Mondays: Erosion

In mountainous regions precipitation – be that in the form of rain, hail or snow, for example – drives erosion, which means it plays an important part in shaping the way the landscape looks. Precipitation can directly wear away at hillsides and creates streams and rivers, which leave their mark on the scenery by cutting and calving their way through it.

Take for instance the hills in the arid coastal region of Pisco Valley, in Peru (pictured above). Contrary to what you might think having first looked at the photograph, very little erosion of rock happens here. The solid rock which makes up the undulating hills is a hard-wearing grantic rock (not dissimilar to the stone you might covet for your kitchen countertops).

Over time, wind-blown sediments have blanketed the granites. Loesses, as the deposits are known, are very soft and range between 20 and 60 cm in thickness. The channels which slice the hillside are carved into the loesses, not the granites which lie below.

Rain is such a rare thing in these parts that soil barely forms (Norton et al., 2015) and it’s impossible for plants to grow on the soft substrate, leaving the slopes exposed to the elements. When the infrequent rains do come, small scale gullies, only a few centimetres deep cut their way into the sediments, taking away material loosened by torrential rainfalls at high speeds.

References

Kevin P. Norton, Peter Molnar, Fritz Schlunegger, The role of climate-driven chemical weathering on soil production, Geomorphology, Volume 204, 1 January 2014, Pages 510-517, ISSN 0169-555X, http://dx.doi.org/10.1016/j.geomorph.2013.08.030.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

 

Laura Roberts Artal is the Communications Officer at the European Geosciences Union. She is responsible for the management of the Union’s social media presence and the EGU blogs, where she writes regularly for the EGU’s official blog, GeoLog. She is also the point of contact for early career scientists (ECS) at the EGU Office. Laura has a PhD in palaeomagnetism from the University of Liverpool. Laura tweets at @LauRob85.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

*