Ball-and-pillow structures

Ball-and-pillow structures (caused by soft-sediment deformation) in the Pebbley Beach Formation (Permian), New South Wales

Ball-and-pillow structures are masses of clastic sediment that take the form of isolated pillows or protruding ball structures. These soft-sediment deformations are usually found at the base of sandstone beds that are interbedded with mudstone.[1] It is also possible to find ball-and-pillows in limestone beds that overlie shale, but it's less common.[2] They are normally hemispherical or kidney shaped, and range in size from a few inches to several feet.

Ball-and-pillow structures, Merry Beach, (Snapper Point Formation), South Coast of NSW
  1. ^ Ailsa Allaby and Michael Allaby. "ball and pillow structure." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 1 Nov. 2010
  2. ^ Boggs, S., 2006, Principles of Sedimentology and Stratigraphy (4th ed.), Pearson Prentice Hall, Upper Saddle River, NJ, p.94-97