Review Article On The Origin Of Mountains

Simon Lamb and Anthony Watts have published a review article on the Origin of Mountains in a recent issue of Current Science. This volume has a special section: Perspectives on Earth Sciences 2010.

The article discusses at length the basic principles of mountain building.. isostacy, crust mantle density and thickness contrasts, horizontal forces,  lithosphere and asthenosphere strength and flow characteristics along with examples from the Andes and Himalayas and plenty of neatly annotated figures.

There is a nice symmetry to the way it ends, suggesting that the nuclei of stable continental crust are forged in the weak interior of great mountains:

An intriguing final insight of all this is that the central highly deformed parts of mountain belts, by being such weak and mobile parts of the Earth, may be the places where the strong cratonic cores of the continents were first formed, comprising what are today the most stable parts of the dry land we live on. This is because the process of mountain building, by squeezing both the crust and mantle parts of the lithosphere, creates a thick lithosphere.

Over time, as geotherms relax and the crust heats up as a result of the increased radiogenic heat generation in the thickened crust, granulite grade metamorphism will occur, eventually dehydrating and further strengthening the crust. If, at some later stage, the crust in this thick lithosphere is eroded back down to its original thickness of around 30–40 km, as isostasy would predict, the land surface will return to around sea level, but with the deep crustal levels of granulite grade metamorphic basement now exposed at the surface. So, as has been long suspected by geologists, mountain building, although occurring in only a small fraction of the surface area of the continents at any one time, might have shaped most of the Earth’s continental crust.

Graduate students and educators should find this a very good resource to brush up on the fundamentals.