Spheroidal Weathering in a Basalt Outcrop

June 25, 2015


Photographer: Francisco Sousa
Summary AuthorFrancisco Sousa
This basaltic outcrop near Bergama, Turkey, is an example of spheroidal weathering. With this type of erosion the basalt's subsurface is already fractured by joints or cracks. Blocks, defined by the joints, become rounded as the concentric layers forming the block surfaces are separated. The shape and size of boulders such as this one are determined by the spacing of joints in the intact rock mass. Spheroidal weathering is common in basalt and granite and is also found in dolerites, andesite and some sandstones. Photo taken on August 10, 2013.
Photo Details: Canon PowerShot G9 camera; Focal Length: 7.4mm focal length; f/4.0; 0.0008 sec. exposure time; ISO 80.