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Bt4

Material name:	Bt4
Synonyms:	N/A
Material (geologic):	Flint from the Middle Bathonian of the so-called "choin" formations

Foto: Jehanne Féblot-Augustins, 2005.

Sampled sites:

Le Plan
Balme à Juliette 2
Tenay-Lower quarry 1
Mont de la Vavre
Gardon-Chemin 1 et 3
Merland-Pierrefeu 1
Combe Jélisse
Mont Ravet
Sous la tour

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Material description

Mode of occurrence: Large globular or ramified nodules (10 to 20 cm across), occurring either at the boundary between two limestone beds, or within the limestone beds (Tenay); smaller nodules (10 cm max.) forming silicified zones within the limestone and not easily distinguished from the enclosing rock (Balme à Juliette).

Cortex: Ranging from thin to thick, transition gradual.

Colour: Very light grey (10YR 7/1 to 8/1) to light blue-grey (N6.5).

Pattern: Outer portion a very light grey, featureless or splotched/mottled with blue-grey; centre generally featureless (blue-grey) with a few darker specks (pellets, 1500 µ).

Appearance: Dull and opaque; outer portion not homogeneous, rough and coarse-grained; centre is homogeneous, smooth and fine-grained; overall, the Tenay material is less fine-grained.

Structure: Convoluted bioturbation figures.

Texture: Mudstone/wackestone (Balme à Juliette), wackestone (Tenay)

Matrix: Opaque, to semi-opaque in the bluish areas.

Grains: 10 to 15 % (Balme à Juliette), 25 to 30 % (Tenay), subrounded with high sphericity, well sorted (100 µ), a shiny pale yellow in the featureless light grey areas, white in the bluish areas; rare elements of 600 µ, 1500 µ and 2000 µ.

Grain composition: Numerous thick-walled sponge spicules (transversal sections mainly), pellets, short microfilaments (Posidonomya test sections), pelecypod fragments, rare entrochi and serpulids; a few 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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Le Plan

Locality:	Ambérieu-en-Bugey / Vareille - Le Plan, France, Ain department
Synonyms:	Sampling site Bugey 14 after Féblot-Augustins
Geographical description:	The source lies on a hilltop approx. 1 kilometre east of the hamlet St. Germain, a couple of kilometres southeast of Ambérieu-en-Bugey.
Geographical co-ordinates:	east/x 836.4 north/y 2110 (Lambert zone II, NTF) This corresponds roughly with Lat. 45° 56' 56" N Long. 005° 23' 11" E (WGS84)
Co-ordinate precision:	The coordinates given were taken from a large-scale map, and are within approx. 50 - 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, so don't be deceived by the apparently high precision to the second. The location can be found on the 1:25 000 topographical map sheet 3130 E of the French Institut Géographique National.
Geology:	The underground at the sampling-site is a clay-with-flints which resulted from the decalcification of several flint-bearing formations dating to the Bajocian and Bathonian (units J1a-b and J1c from the Bajocian and J2 from the Bathonian). Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Secondary.
Other types of flint:	Besides type Bt4, this residual source also yields Late Bajocian flints of the Bj3 and Bj4c varieties, as well as other Bathonian flints of the types Bt1 and Bt.

Foto: Jehanne Féblot-Augustins, 2005

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Balme à Juliette 2

Locality:	Ambérieu-en-Bugey / Les Balmeaux - Balme à Juliette 2, France, Ain department
Synonyms:	Sampling site Bugey 16 after Féblot-Augustins
Geographical description:	The sample comes from an exposure approx. 1 kilometre to the east of Vareille, a hamlet at the eastern side of Ambérieu-en-Bugey. The site of Balme à Juliette 2 lies just 20 yards below the sampling site of Balme à Juliette 1. Both are located in a small cavity just above the Gardon cave, and the material was extracted from the walls. Due to extensive faulting of the area, the stratigraphy is quite complicated, with a block of Bathonian material wedged between the Middle and Late Bajocian layers. This accounts for the fact that the Bajocian Bj4-types (Bj4a, Bj4b and Bj4c) are found topographically above the Bt4 flints, whereas the Bj1-flint occurs at a lower position near Gardon cave.
Geographical co-ordinates:	east/x 836.4 north/y 2110.98 (Lambert zone II, NTF) This corresponds roughly with Lat. 45° 57' 28" N Long. 005° 23' 12" E (WGS84)
Co-ordinate precision:	The coordinates given were taken from a large-scale map, and are well within 50 metres of the actual exposure. The latitude/longitude coordinates are a direct transformation of these data on WGS84 and are accurate to the same level. The high precision to the second is given to prevent the introduction of a rounding-error. The location can be found on the 1:25 000 topographical map sheet 3130 E of the French Institut Géographique National.
Geology:	According to the geological map, the parent-rock belongs to unit J2 of Middle Bathonian age. Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Primary.
Other types of flint:	All flint from this source is of the Bt4 type, although very nearby also Bajocian flint of the Bj4a, Bj4b and Bj4c types can be found.

	Foto: Jehanne Féblot-Augustins, 2005	Foto: Jehanne Féblot-Augustins, 2005
	Foto: Jehanne Féblot-Augustins, 2005	Foto: Jehanne Féblot-Augustins, 2005
	Foto: Jehanne Féblot-Augustins, 2005

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Tenay-Lower quarry 1

Locality:	Tenay / Lower quarry 1, France, Ain department
Synonyms:	Sampling site Bugey 17 after Féblot-Augustins
Geographical description:	The sample comes from a quarry at the foot of the mountain directly to the northwest of Tenay.
Geographical co-ordinates:	east/x 845.9 north/y 2107.3 (Lambert zone II, NTF) This corresponds roughly with Lat. 45° 55' 17" N Long. 005° 30' 26" E (WGS84)
Co-ordinate precision:	The coordinates given were taken from a large-scale map, and are within approx. 50 metres of the actual spot. The latitude/longitude coordinates are a direct transformation of these data on WGS84 and are therefore also within the same error-margin. 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 the middle part of unit J2 (Bathonian). Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Primary.
Other types of flint:	From the same quarry also comes flint of the Bt1 type, which can be found 30 yards to the east in a stratigraphically somewhat lower position.

	Foto: Jehanne Féblot-Augustins, 2005	Foto: Jehanne Féblot-Augustins, 2005
	Foto: Jehanne Féblot-Augustins, 2005

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Mont de la Vavre

Locality:	St-Martin-du-Mont / Mont de la Vavre, France, Ain department
Synonyms:	Sampling site Bugey 27 after Féblot-Augustins
Geographical description:	The sample was collected at the eastern foot ot Mont de la Varve, just west of the narrow road that connects the hamlets of Turgon and Confranchette d'en Bas.
Geographical co-ordinates:	east/x 831.2 to 831.8 north/y 2125..3 to 2125.7 (Lambert zone II, NTF) This corresponds roughly with Lat. 46° 05' 24" N Long. 005° 19' 51" E (WGS84)
Co-ordinate precision:	The coordinates given were taken from a large-scale map, and as the site is several hectares in size, they are good enough for a clear indication. The latitude/longitude coordinates point to a spot near the middle of the area. The location can be found on the 1:25 000 topographical map sheet 3129 E of the French Institut Géographique National.
Geology:	According to the geological map, the substrate is a clay-with-flints, a residue of the erosion of Bathonian limestones. Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Secondary.
Other types of flint:	Although the site is a secondary source, all material is of the Bt4-type.

Foto: Jehanne Féblot-Augustins, 2005

Foto: Jehanne Féblot-Augustins, 2005

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Gardon-Chemin 1 et 3

Locality:	Ambérieu-en-Bugey / Les Balmeaux - Gardon, Chemin 1 et 3 , France, Ain department
Synonyms:	Sampling site Bugey 30 after Féblot-Augustins
Geographical description:	The sampling location is located at the foot of a steep cliff near Gardon cave, approximately 2 kilometres east of Ambérieu-en-Bugey.
Geographical co-ordinates:	east/x 836.4 north/y 2110.8 (Lambert zone II, NTF) This corresponds roughly with Lat. 45° 57' 22" N Long. 005° 23' 12" E (WGS84)
Co-ordinate precision:	The coordinates were read off a large-scale map, and are within approx. 50 metres of the actual spot. The transformation to lat/long was performed on the exact figures given for the Lambert-coordinates, so their precision is in the same order of error. The location can be found on the 1:25 000 topographical map sheet 3130 E of the French Institut Géographique National.
Geology:	The sample was collected from a secondary position on the surface, and is presumably weathered from limestones of Early and Middle Bathonian age. Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Secondary.
Other types of flint:	Apart from Bt4 flint, also material belonging to the type Bt1 can be found here.

Foto: Jehanne Féblot-Augustins, 2005

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Merland-Pierrefeu 1

Locality:	Ambronay / Merland - Pierrefeu 1, France, Ain department
Synonyms:	Sampling site Bugey 31 after Féblot-Augustins
Geographical description:	The site is located in wooded area, half a kilometre Souteast of the hamlet of Merland, two kilometres east of Ambronay and a bit over 100 metres west of sampling site Merland-Pierrefeu 2.
Geographical co-ordinates:	east/x 836.45 north/y 2115.8 (Lambert zone II, NTF) This corresponds with Lat. 46° 00' 04" N Long. 005° 23' 23" E (WGS84)
Co-ordinate precision:	The coordinates given were taken from a large-scale map, and are within 50 metres of the precise point. The latitude/longitude coordinates are a direct transformation of these coordinates on WGS84 and lie within the same error-range. The location can be found on the 1:25 000 topographical map sheet 3130 E of the French Institut Géographique National.
Geology:	The material can be found in residual loams, the erosional residue of the weathering of Bathonian limestones in which the chert was embedded originally. Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Secondary.
Other types of flint:	All material from this location is Bt4 flint, although residual Bajocian chert of the Bj3 type can be found at the nearby location of Merland-Pierrefeu 2.

Bathonian material from clay-with-flints

Foto: Jehanne Féblot-Augustins, 2005

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Combe Jélisse

Locality:	St-Jean-Le-Vieux / Cheminand - Combe Jélisse 2, France, Ain department
Synonyms:	Sampling site Bugey 33 after Féblot-Augustins
Geographical description:	The source is located near a slight valley in the Bois de Fayat, a bit over a kilometre and a half southeast of the hamlet St-Jean-le-vieux, which lies some four kilometres southeast of Pont-d'Ain.
Geographical co-ordinates:	east/x 837.2 north/y 2117.4 to 2117.6 (Lambert zone II, NTF) This corresponds roughly with Lat. 46° 00' 58" N Long. 005° 24' 01" E (WGS84)
Co-ordinate precision:	The coordinates give the approximate extention of the source, and were teken from a large-scale map. The latitude/longitude coordinates indicate a point near the centre of the area. 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 Rs (clay-with-flints), erosional restst of Bathonian J2 limestone. Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Secondary.
Other types of flint:	No other type of flint besides Bt4 is known from this source.

Foto: Jehanne Féblot-Augustins, 2005

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Mont Ravet

Locality:	St-Rambert-en-Bugey / Mont Ravet, France, Ain department
Synonyms:	Sampling site Bugey 37 after Féblot-Augustins
Geographical description:	The flint was sampled a kilometre south of the hamlet Angrières in a narrow valley at the western side of Mont Ravet, a kilometre west of St- Rambert-en-Bugey,
Geographical co-ordinates:	east/x 839 north/y 2109.4 to 2110 (Lambert zone II, NTF) This corresponds roughly with Lat. 45° 56' 43" N Long. 005° 25' 11" E (WGS84)
Co-ordinate precision:	Even if the Lambert coordinates were taken off a detaile topographic map, the are accurate enough as the site is quite extended. The latitude/longitude coordinates are a direct transformation of the approximate centre of the source-area, and shouldn't be taken to the nearest metre. 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 XXX. Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Secondary.
Other types of flint:	All flint here is from the same Bt4-type.

Foto: Jehanne Féblot-Augustins, 2005

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Sous la tour

Locality:	Abergement-de-Varey / Sous la tour, France, Ain department
Synonyms:	Sampling site Bugey 38 after Féblot-Augustins
Geographical description:	The flint was collected at the northern side of the elongated large hill/mountain directly to the west of Abergement-de Varey, not far from the road that connects this village with Ambronay.
Geographical co-ordinates:	east/x 838.7 north/y 2117 (Lambert zone II, NTF) This translates to Lat. 46° 00' 40" N Long. 005° 25' 10" E (WGS84)
Co-ordinate precision:	The coordinates given were taken from a large-scale map, and are within 50 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, so the seconds are only given to prevent the introduction of a rounding-error. The location can be found on the 1:25 000 topographical map sheet 3230 W of the French Institut Géographique National.
Geology:	The substrate is a residual clay-with-flints, where the flints com originally from Middle Bathonian rocks of the "choin"-formation. Map of all sampled localities of Bathonian flint in the Bugey (PDF, 195 KB, opens in new window).
Type of source:	Secondary.
Other types of flint:	All flint from this locality seems to be of the Bt4-variety.

Foto: Jehanne Féblot-Augustins, 2005

Last modified on:
November 15, 2005

Contents primarily by:
Jehanne Féblot-Augustins

Comments to:

Mode of occurrence:	Large globular or ramified nodules (10 to 20 cm across), occurring either at the boundary between two limestone beds, or within the limestone beds (Tenay); smaller nodules (10 cm max.) forming silicified zones within the limestone and not easily distinguished from the enclosing rock (Balme à Juliette).
Cortex:	Ranging from thin to thick, transition gradual.
Colour:	Very light grey (10YR 7/1 to 8/1) to light blue-grey (N6.5).
Pattern:	Outer portion a very light grey, featureless or splotched/mottled with blue-grey; centre generally featureless (blue-grey) with a few darker specks (pellets, 1500 µ).
Appearance:	Dull and opaque; outer portion not homogeneous, rough and coarse-grained; centre is homogeneous, smooth and fine-grained; overall, the Tenay material is less fine-grained.
Structure:	Convoluted bioturbation figures.
Texture:	Mudstone/wackestone (Balme à Juliette), wackestone (Tenay)
Matrix:	Opaque, to semi-opaque in the bluish areas.
Grains:	10 to 15 % (Balme à Juliette), 25 to 30 % (Tenay), subrounded with high sphericity, well sorted (100 µ), a shiny pale yellow in the featureless light grey areas, white in the bluish areas; rare elements of 600 µ, 1500 µ and 2000 µ.
Grain composition:	Numerous thick-walled sponge spicules (transversal sections mainly), pellets, short microfilaments (Posidonomya test sections), pelecypod fragments, rare entrochi and serpulids; a few 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.