| Gault of Aube region department (France) :Local
stratigraphy |
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| The fossils which you will be able to see on
these modest pages Internet result primarily from the career of Courcelles,
to 10 km of Troyes approximately. In Courcelles we are into full in the
outcrops with the average gault. Work of the A5 motorway and the new Aube
tank (very close to Brévonnes) towards the end of 1980 also revealed
the same outcrops. As soon as one goes towards south-east one passes worms
of the older layers gradually (lower Gault... Aptien... Barémien...
Hauterivien...) then the Jurassic superior with Portlandien with height
of the Bar-on-Seine. In western north one quickly discovers the chalky zones
of the higher cretaceous (Cénomanien... Turonien); higher gault or
not being represented little if they are not the marls of Brienne. |
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In Courcelles, we primarily found
fossils preserved well in the zone "B" of the coal face of exploitation
of the argillaceous hill. That corresponds approximately to the level of
the road. That should be relativized, because we are not in front of a regular
ground with the mathematical direction. All these argillaceous sedimentary
layers undulate, and, even if there is a general dip of sleep towards the
Paris basin, locally one to find the same ones little sleep with heights
different on space from a few tens of meters. |
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This zone "B" is characterized by the presence of a calcareous
level composed of more or less ovoid blocks, block which contain fossils
of very good conservation with their shell (that one names "test"
in paleontology).
Above and below this "limestone deposit" one finds also fossils,
but most often intern moulds some or almost. More one moves away from
this calcareous layer plus the fossils in a "solid" state make
place with simple soft prints in clay.
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These prints are coloured and brilliant in the first moment of their
setting to the free air, but oxidize quickly in contact with oxygen. The
"solid" fossils but not coated with their shell "test",
also deteriorate in time with the ambient moisture of the air + oxygen,
but that over several years, and in the absence of particular treatment.
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Fossils most commonly found under the ammonites, and more particularly
"hoplites dentatus". These hoplites is declined
in alternatives thickness, ornamentation, of very variable sizes.
One finds there also the splendid ammonites will douvilleceras whose this
level seems to be progressive disappearance.
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| One should not omit either all the
small surrounding fauna of gastropods, lamellibranches and
others, which is quite present and often of excellent conservation. |
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