A Tempestit - from Latin tempestas ( tempest, storm, stormy period ) - is caused by storms near the coast sand or Siltlage, which has a larger distribution and sharply settles against the surrounding silt. Tempestite are also called sand storm situation, they are not only found in the sea, but also in lakes.
The storm sand layers go back to the fact that severe storms washing away sand and silt from the coast and bring in suspension in seawater. The resuspended sediment spreads several tens of kilometers to the shelf area of the environment and accumulates according to the new size. The grain size of the deposited sediment from the bottom to the top and with increasing distance from the coast always fine. The characteristic sequence of layers of storm deposits is called Dott -Bourgeois sequence.
Sediments with Tempestitcharakter often exhibit wavy or beulige stratifications. In some cases, solidified or partially solidified layers already be solved by storm waves from the ground and as a tangled mess again deposited (see picture). The repeated deposition of sand layers on water-saturated seabed sediments can lead to the formation of sedimentary crossings by the pressurized water escapes upward and generates vertical, filled by sediment transitions.
Tempestite be examined about the Paläotempestologie and provide the opportunity to assess the frequency and severity of which occurred in the past storms or tsunamis. However, the distinction whether a Tempestit was caused by storm events or by a tsunami is difficult and requires a deep investigation and good outcrops.
Marked by geological storms rock layers can be detected in many parts of the world based on the characteristic storage in fine-grained sediments and the absence of the typical signs of turbidites in participating in the deposition currents.