The seismic events
During the sedimentation of the chalk, earthquakes occurred and some of them were violent enough to engender what we call séismites.
We indicate under the name of séismite (Seilacher, on 1969, sometimes still sismite) sedimentary coats presenting structures of deformations in situ led
By a seismic shock. A big variety of structures can be engendered according to the consolidation and the composition of the sediment.
Most of the séismites described in the geologic literature interest detrital sediments, particularly alternations sand-clay for which he is convenient to analyze the geometry. In a sediment of tint homogeneous as the chalk, the possible seismic structures are more difficult to spot, except when in the chalk fit levels of flint. Chalks in the SW of the syncline of Ailly are in this case and it is mainly in this region that séismites is described here.
Here is an example of séismite, in him E of Veules-les-Roses and the corresponding interpretation:
A model of the séismites of the chalk
Certain number of structures testifying of the action of an earthquake is specific in the chalk. They were described to Eletot or to Veules-les-Roses and can be gathered on this plan. Other structures as boudinage and synthetic break in rhombuses of flints can be mentioned.
List of seismic events
- Flints in basin infra-Brighton [W of the staircase of Sotteville]]
- The séismite Buckle [Port of Moutiers]]
- The séismite Anglesqueville (infra-Exceat and above pair of shorts Brow) [Port of Moutiers Est, Veules Est]]
- The séismite Ormelet (infra-Ormelet and above rough Brow / W3?) [Veules Ouest]
- Penitent séismite (infra-rough Brow / W3? And above - Brasspoint) [Fill Moutiers Ouest, Veules Ouest, Veules Ouest near a faile, Saint-Valéry Ouest]]
- Bedwell's séismite columnar [pparking lot of western Saint-Valéry, parking lot of the casino, the overflow: a video, a collapsed bunker St Valéry W]]
- The séismite Escamet (above - Veulettes and infra-Michel Dean):Premier Avaleux, Saint Valéry W side E of the basin of the bunker.
- The séismite Saint Sylvain (infra-Veulettes) [The first one Avaleux Est, valleuse 46 is, hillock of Escarmet]
- The séismite Câtelier (infra Cuckmere 2) [Five Holes summit, Five Holes is, casino of Veulettes, Spur of Veulettes Est, the Coast in Herons Dieppe W]]
- The séismite Dieppe 1 (includes the flint Seven Sisters and the underlying coats) [Gulp down Them of western Dieppe, Veulettes W the Plain of the cliff]]
- The séismite Grainval 2 [ex:Grainval]
- The séismite Grainval 1 (above beautiful Everything) [ex:Grainval]
= Chaotic coat Bénouville [iin him W of Etigue station D, in him W of Etigue station B, western side of the basin of the Hague Est, western Vattetot, the hillock of Vattetot, the pit to the Deaf persons, the Nose of Vaucottes, Course of the Virgin the West, Yport Est]
- The séismite infra-Shoreham [ex: in the valley Saint Martin in him E of Criel]]
- The unity slumpée above - Hope Gap [CCap Vaudieu SW, Rock Vaudieu, in N of the Rock Vaudieu]]
- The unity slumpée infra-Hope Gap [Ex:esplanade of Criel]
- Séismites above - Lewes [the first one séismite ex:Saint-Pierre W summit and base and second séismite ex:Saint-Pierre W]]
- The séismite infra-Lewes [ex:E of the Valley Pollet, Mesnil-valley]]
- The likely séismite infra-Southerham [ex:W of the Valley Ausson]]
- The marl Fourquet [ex:Pointe of Fourquet]]