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Material name: Bj2
Synonyms: N/A
Material (geologic): Middle Jurassic (Early to Middle Bajocian) flint/chert

Detail of Bj2 flint
Foto: Jehanne Féblot-Augustins, 2005.

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Material description

Mode of occurrence: Joining nodules forming siliceous beds 6 cm thick.
Cortex: Rough, light reddish tan, 1 cm thick, transition sharp.
Colour: Dark (bluish) grey (N4).
Pattern: Laminations 2 to 4 mm thick, lighter hues alternating with darker tones.
Appearance: Homogeneous material, dull and opaque, rather rough and coarse-grained.
Structure: Laminated, corresponding to differences in colour and texture, irregular bands of more or less milky matrix (recrystallized as chalcedony); frequent micro-vugs.
Texture: Wackestone (milky zones) to packstone.
Matrix: Milky to more translucent.
Grains: 20 to 40 %, irregularly shaped, rounded, poorly sorted (100 to 400 µ, overall impression 3-400 µ).
Grain composition: Peloids, foraminifera showing as "ghosts" outlined by impurities, numerous monaxon or triaxon sponge spicules, thick-walled and recrystallized as chalcedony; abundant grains of iron oxides.
Further information: Click here for the original French description (opens in a new window), or here for more information on the attributes used in the description (use your browser's "BACK"-button to return here).
Citing: Information on citing this page can be found here.

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La Courbattière
Locality: Jujurieux / La Courbattière, France, Ain department
Synonyms: Sampling site Bugey 7 after Féblot-Augustins
Geographical description: The source is located on a wooded slope facing the hamlet of La Courbattière, approx. 1 km southeast of Jujurieux.
Geographical co-ordinates: east/x 838.50
north/y 2119.3
(Lambert zone II, NTF)

This corresponds roughly with
Lat. 46° 01' 55" N
Long. 005° 25' 05" E

Co-ordinate precision: The coordinates given were taken from a large-scale map, and are within approx. 50 to 100 metres of the actual spot.
The latitude/longitude coordinates are a direct transformation of these data on WGS84 and are accurate to the same level, the suggested higher precision is given to avoid the introduction of a transformation error.

The location can be found on the 1:25 000 topographical map sheet 3230 W of the French Institut Géographique National.

Geology: According to the geological map, the substrate belongs to unit l9b-J1b (Early Aalenian and Early-Middle Bajocian).

Map of all sampled localities of Bajocian flint in the Bugey (PDF, 190 KB, opens in new window).

Type of source: Primary.
Other types of flint: All flint from this source belongs to type Bj2, and is, up to now, the only occurrence of this type of material.
  Piece of coarse Bj2 flint with cortex
Foto: Jehanne Féblot-Augustins, 2005


Last modified on:
November 15, 2005
Contents primarily by:
Jehanne Féblot-Augustins
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