"Chisel marks" on columnar joint face

• Other Authors: Wojtal, Steven F.
• Format: Other/Unknown Material
• Language: unknown
• Published: Oberlin College Library 1997
• Subjects: Geology; Structural; Joints (Geology); Columnar joints; Austurland; Skaftafell; Iceland
• Online Access: http://server15963.contentdm.oclc.org/u?/p15963coll1,1697

The sides of any columns in columnar jointing do not form a single uniform fracture, rather they grow incrementally. Each subhorizontal fracture increment, known as a "chisel mark," has its own fracture surface markings that indicate the direction of growth of that fracture. Most fractures here propagated from left to right across the column face, and most of these fractures initiated along the lower edge of the chisel mark.