1. A lineation on a fault or bedding plane caused by the frictional movement of one rock body against another. The plane may be coated by a mineral, often quartz or calcite, which itself shows striations in the direction of movement.
2. The polished surface left by the passage of a mud slide.
3. In soils, the natural crack surfaces produced by swelling and shrinkage in clayey soils that are high in swelling clays.