Peering into the Cracks
A recent article in Reviews of Geophysics combined mathematical modeling, fracture mechanics theory and engineering research data to provide new insights into a critical geological process.
There is a long-standing question of how climate, particularly water, may influence the physical breakup of rock when it is exposed to the elements. It is typically assumed that the importance of water in rock cracking arises from the role that it plays in processes like freeze-thaw that require water to proceed. Here, we use classical mathematical models combined with a compendium of fracture mechanics theory and data from engineering research to show, for the first time, that water likely influences all types of rock cracking at Earth's surface whether it “requires” water or not. We also show that cracking proceeds even when only extremely low stresses are applied to the rock (akin to very small pulling forces). These stresses can be due to occurrences as simple and ubiquitous as daily heating and cooling by the sun.
Picture: Macrocracks in a granite dome outcrop of Stone Mountain, North Carolina. Credit: Martha Cary Eppes
