Rock Recycling

The process of weathering, the breakdown or decay of rock, forms the physical geography all around us.  Weathering is not to be confused with the common term, erosion which is the transport of weathered material.  However, these two processes can work together in order to create magnificent physical features.

Large fractures in rock are known as joints.

Physical weathering, otherwise known as mechanical weathering, is known as the disintegration of rocks and minerals by a physical or mechanical process.   Many different types of weathering exist and examples of these processes can be found throughout the Red Rocks Amphitheatre and the surrounding areas. 

Joints can be identified as regularly spaced fractures or cracks in the rocks.

A common form of weathering found in the area is known as frost weathering.  This process most often occurs in high altitudes, such as the Rocky Mountains, where water freezes and thaws often.  Water will seep into joints, freeze, and expand by up to 11%.  This expansion exerts force on the surrounding areas and results in weathering.

With snowfall comes melting and refreezing, resulting in expansion and weathering.

Another common form of weathering in the area is known as basal weathering.  The name basal weathering is due to the weathering around the base of a rock.  This process occurs over centuries as running water slowly weathers the base of a rock, with the weathered material carried away through erosion.

Basal, as well as other forms of physical and chemical weathering  can be found at Red Rocks.

A process of chemical weathering, (biological) organic acids can also weather rock.  When vegetation such as mosses and lichens grow on rock they leach chemicals weakening and weathering the material.  Another from of chemical weathering; salts can create cavernous weathering on vertical faces, these large holes on the side of the rock are known as tafoni.

A third type of physical weathering which occurs in the area is weathering through the pressure of roots.  As plants grow, their roots extend downward into cracks and fractures in the Earth.  The pressure of this growth causes the cracks to expand resulting in larger fractures.

The more vegetation on a rock surface, the more weathering will occur. Root pressure fractures can be seen throughout Red Rocks Amphitheatre.

With weathering constantly occuring, the weathered materials are eroded away and deposited; eventually becoming soil.  Over time the soil will settle into distinctive horizontal layers, based upon climate, living organisms and configuration of land surface, forming a soil profile.

This soil profile from Red Rocks shows O-K horizons

Each soil horizon has properties of its own based upon physical, chemical and organic composition

                                                       

Soil can be looked at as a closed cycle.  All of the materials will be recycled within the system forming new rocks which return to soil and eventually repeat the process.


Sources:
http://clasfaculty.ucdenver.edu/callen/1202/Soils/Soils.html
http://images.cdn.fotopedia.com/flickr-3828340682-hd.jpg
http://denver.ettractions.com/storage/attraction/thumb/red-rocks-denver-rocks.jpg
http://marlimillerphoto.com/images/WE-18.jpg
http://farm8.staticflickr.com/7162/6592126337_04f2141718_z.jpg