Geological structures

Geological structures

1. Unconformity = a period when no sediment was deposited

   • Angular conformity = the rocks above and below the unconformity have different dips, and possibly strikes

2. Joints

   • A fracture in competent rocks along which no observable movement has occurred
   • Tectonic joints = form as a result of folding and cause tension joints parallel to the axial plane and cross joints on the limbs
   • Cooling joints = form as a result of contraction on cooling of igneous rocks
   • Unloading joints = form as a result of lower pressure near to the surface, they are often horizontal as well as vertical