Landscape Evolution

Scientists have struggled with a lingering question in geology. Why do the structures and elevations of some mountains continue to evolve long after the tectonic activity that formed them have ceased – see https://phys.org/print446805209.html … and modelling has come to the rescue (or sort of). Sean Gallen from Colorado State University combined modelling with field research in a quite clever way to record the ebb and flow of activity in mountains in two national parks in the US. Activity clearly continued even after it was tectonically quiet. It is not all about wind and rain and frost erosion – the hardness of the rocks is a major factor. In this case he showed why the Tennessee River made a long detour before meeting up with the Ohio River, all down to geology. His paper is published in Earth and Planetary Science Letters which confounds some old theories. For instance, geologist thought rugged mountainous terrain is slowly eroding away to a flat surface once a tectonic event was over – but he discovered mountain landscapes continue to form  due to variations in the manner of erosion and the hardness of the rocks. For instance, waterfalls play a role, and rivers are diverted for various reasons.