March 16, 2018

Pulling apart

Posted by larryohanlon

Sometimes you have to build the field in the lab. At the Virginia Tech Active Tectonics and Geomorphology Lab researchers do just that. This is the latest in a series of posts shared from their blog. More of their posts can be found here.

Most of the time in this blog we discuss collision which makes us thing about compressional forces. This time we’re going the opposite direction and investigating what we  can replicate with sandbox models in terms of extension, or when the continents are under tensional forces. This gets me thinking about pull-apart bread as geologists love food analogies.


In this video Phil shows the formation of normal listric faults occur as two continents pull away from each other much like what is occurring in the Basin and Range in the Western United States (or in the bread above).


Normal faults form as the hanging wall moves downward relative to the foot wall. In a listric normal fault the fault plane or where the hanging wall and foot wall touch isn’t plane so much as it’s scoop shaped.

Images: and

This blog was originally posted at