The Sandettie Bank (French: Banc de Sandettié) is an elongated sandbank in the southern

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...

, more specifically about in the middle of the northeastern entrance to the Strait of Dover. North-west of it are the hazardous

Goodwin Sands Goodwin Sands is a sandbank at the southern end of the North Sea lying off the Deal coast in Kent, England. The area consists of a layer of approximately depth of fine sand resting on an Upper Chalk platform belonging to the same geologi ...

, south of it the sandbank Ruytingen. The shoal represents a significant threat to the major shipping lanes in the Strait of Dover. From 1902 to 1989 it was marked by a succession of French lightships, all bearing the name ''Sandettié'' while deployed there. The last such manned lightship is now a museum ship at the Port Museum of Dunkirk at anchor. Today the British authority

Trinity House "Three In One" , formation = , founding_location = Deptford, London, England , status = Royal Charter corporation and registered charity , purpose = Maintenance of lighthouses, buoys and beacons , he ...

maintains an unmanned lightship there, the Sandettie Light Vessel Automatic which also has an automatic

weather station A weather station is a facility, either on land or sea, with instruments and equipment for measuring atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include tempera ...

Geology

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

strata form the basement in the Sandettie Bank. In the northwest part of the area

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

cut a basin in the Tertiary strata. This basin is filled with a sequence of late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

sands overlain by

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

sands which form the major topographic features of the Sandettie. The surface of the banks are moulded into transverse ridges up to 10m in

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...

and 200m in

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...

. There are three types of ridges present: # At the north end, linear transverse ridges of irregular amplitude and wavelength occur with a

flint Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Flint was widely used historically to make stone tools and sta ...

gravel base grading up into medium

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class o ...

. These ridges are fossil features of Preboreal- Subboreal age. # At the south end are symmetrical sandwaves of regular amplitude and wavelength which appear to be stable. # To the west of Sandettie Bank there are south-facing asymmetrical sandwaves which are potentially mobile and which later sedimentological investigations revealed to be moving southwards in one area.

Downs herring

The area around the Sandettie Bank is the most important

spawning ground Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

of the Downs herring, a major subset of the Atlantic herring in the North Sea. During the twentieth century overfishing had threatened the fish population, and in 1958 fishing restrictions were imposed in the area.http://literatur.ti.bund.de/digbib_extern/dk039354.pdf

External links

The optical and acoustic signaling scheme and the radio-signal scheme of Sandettie lightvessel, ie the signal pattern of the light signal, the fog horn and the radio station
in accordance with NOTICE TO MARINERS 2/2012 C1 Sandettie Light Vessel No.2/12 C1, by Order Captain R. H. Barker, Director of Navigational Requirements, Trinity House, London, EC3N 4DH, 11 January 2012 Observations and Weather

of metoffice.gov.uk * ttp://cspf.co.uk/sandettie-data The exact course of the air temperature and water temperature as well as the water height in the area of Sandettie Bankon the web page of the Channel Swimming & Piloting Federation on the basis of the data of Sandettie Lightvessel
Weather forecast and wave prediction for the area of the sandbank for skipper
from Meteo Consult Marine, (fr)

References

{{reflist Sandbanks of the North Sea English Channel Sandbanks of England Landforms of Metropolitan France