Weathering and Landforms Topics

Weathering (Part 2)

Physical Weathering (continued)


• Exfoliation is caused by the expansion of rocks when pressure is released as overlying rocks are eroded away.  Exfoliation creates curved surfaces.

Spheroidal Weathering
Exfoliation in shales (Photograph by Parvinder Sethi)

MapCurved slabs of rock have weathered as a result of exfoliation in these Devonian shales exposed in the Valley and Ridge in Highland County.

408 to 360 million years ago


Organic Activity

• Organic activity, or activity by plants and animals, can also cause physical weathering.  Tree roots that grow into crevices and small animals that burrow can cause physical weathering.

Tree Roots
Tree roots pushing rocks apart (Photograph by Robert Whisonant)

MapThese tree roots are wedging rocks apart in the Blue Ridge of Botetourt County.  Tree roots along cliff faces or steep slopes can cause rocks to weather out and fall or slide.