home ]


Material name: T3
Synonyms: Freshwater chert
Material (geologic): Cenozoic (Tertiary) flint

Macroscopic view of T3 flint
Foto: Jehanne Féblot-Augustins, 2005.

top ] [ home ]

Material description

Mode of occurrence: Large globular nodules.
Cortex: Smooth, irregularly rolled with traces of impact, 1 to 5 mm, cream-coloured, thick with well preserved colonial bryozoans as much as 4 cm long.
Colour: Core light bluish grey (N7), outer parts light brownish grey (10YR 6/2).
Pattern: Core is featureless, outer parts are mottled bluish and brownish grey.
Appearance: Very hard chalcedonic flint, reasonably homogeneous, dull and opaque, rather dry, medium grained.
Structure: Convoluted bioturbation figures.
Texture: Textural differences between the bluish areas (mudstone with 1 % grains) and the brownish areas (mudstone 10 %).
Matrix: Fibrous and opaque to milky in the bluish areas, opaque in the brownish areas.
Grains: Alignments of white round dots (125 µ) (rare zooid remnants) in the bluish areas; irregularly shaped zooid fragments (125 to 500 µ) and bryozoan sections (500 µ to 3 cm) in the brownish areas.
Grain composition: Ramified colonial Cyclostoma bryozoans.
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.

top ] [ home ]
Chatanay field pile
Locality: Poncin / Chenavel - Chatanay (pierrier), France, Ain department
Synonyms: Sampling site Bugey 73 after Féblot-Augustins
Geographical description: The material was collected from a heap of stones cleared from the surrounding fields, a kilometre to the SSW of Poncin.
Geographical co-ordinates: east/x 837
north/y 2124,2
(Lambert zone II, NTF)

This corresponds roughly with
Lat. 46° 04' 35" N
Long. 005° 24' 04" E

Co-ordinate precision: As the material comes from the surface, and was then collected in a pile, precision of coordinates is not that important. The figures given are good enough to indicate the general area where this material can be found.
The latitude/longitude coordinates are a direct transformation on WGS84 of the Lambert-values given above.

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

Geology: The material is reworked from a secondary source, so no direct association with geological formations is possible. Judging from the structure and included fossils, it can be inferred the material is probably Cenozoic (Tertiary).

Map of all sampled localities of Cenozoic flint in the Bugey (PDF, 40 KB, opens in new window).

Type of source: Secondary.
Other types of flint: Apart from the T3-type, no other forms of flint were recorded from this locality.
  Nodule of chalcedonic flint
Foto: Jehanne Féblot-Augustins, 2005
Flake of T3 flint
Foto: Jehanne Féblot-Augustins, 2005


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