Rock bedding in a cliff. The vertical lines seen in this cliff-face show how sediments of chalky rocks (of a type known as marls) have been moved over time by tectonic forces. Intersecting this vertical plane is a more diagonal fault pattern (running from upper left to lower right), known as a schistosity. This is due to the rock reacting to the stress exerted on the rock by the same tectonic forces. These rocks date from the Miocene (around 23 to 5 million years ago).