Forest Cover Changes and Trajectories in an ancient Mining area of the Pyrenees from the Antiquity to the 19th c

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Forest Cover Changes and Trajectories in an ancient Mining area of the Pyrenees from the Antiquity to the

19th c

Vanessa Py, Jean-Paul Métailié, Bruno Ancel, Sandrine Baron, Raquel Cunill, Didier Galop, Hugues Barcet, Sandrine Paradis-Grenouillet

To cite this version:

Vanessa Py, Jean-Paul Métailié, Bruno Ancel, Sandrine Baron, Raquel Cunill, et al.. Forest Cover Changes and Trajectories in an ancient Mining area of the Pyrenees from the Antiquity to the 19th c. Kiel international Workshop 2015, Mar 2015, Kiel, Germany. �hal-01197066�

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Forest Cover Changes and Trajectories in an ancient Mining area of the Pyrenees from the Antiquity to the 19th c.

Ariège, France

**Vanessa Py-Saragaglia*, Jean-Paul Métailié, Bruno Ancel, Sandrine Baron, Raquel Cunill i Artigas, Didier Galop, Hugues Barcet & Sandrine Paradis-Grenouillet**

T his study is a part of the interdisciplinary project FODYNA which is focused on an ancient mining area of the Pyrenees (fig. 1) located in the Province of Couserans. This area has differed from silver-lead and copper ore deposits, and from the traces of the road that have connected the Vicdessos to the "Port de Saleix" for centuries, which were used, since the 14th c., for the iron/charcoal exchange that was sealed with Vicdessos – a steel valley which sought to safeguard its wood resources. !

!

Its main objectives are: !

•  to characterise and to date the archaeological remains of mining and ore processing activities;!

•  to determine the geochemical imprint of lead ores that were exploited locally;!

•  to measure the impact of these activities on changes and trajectories of woodland cover;!

•  to understand the impact of charcoal burning and mining (firesetting) on soil charcoal concentration and anthracological assemblages.!

FIG. 1 Location of the study area (a) and its 3D view (b) with the location of sites and sampling points (Barcet, unpublished)!

Charcoal kilns!

Mining remains!

Reference point!

Pedoanthracological pit!

Pedoarchaeological pit!

a!

Vicdessos Couserans

Aulus-les-Bains!

T he chronology of protoindustrial remains is based on a detailed archaeological survey (fig. 2, a) of which the data were included in a GIS, AMS

¹⁴

C, and textual data (Py et al., 2014).!

A pedo-archaeological pit was opened in a heap waste (fig. 2, c), associated with a trench affected by firesetting marks (fig. 2, b), for sampling galena fragments and residual charcoals (fig. 2, c).!

!

O ther galena fragments were sampled in 18th c. Lacore works (fig. 2, a); !

31 charcoal kilns (fig. 1, b) were sampled with a soil auger; charcoals were identified; growth rings were counted and their curvature (curved, intermediate, straight) and the felling season were evaluated;!

2 pedo-anthracological pits were opened on the Lacore side (fig. 1, b).!

FIG. 2 (a) Map of both mining sectors with samples ( ) location; (b) trenche with firesetting marks ; (c) stratigraphic cut of pedo-archaeological pit (Ancel, Py, Barcet, unpublished)!

b. !

a. ! b. ! c. !

50 m !

14C AMS !

C hronology and imprints of local mining activities!

Archaeological and

¹⁴

C data reveal that a first mining phase occured during the Roman period (151 cal BC-55 cal AD) in the "Les Argentières" sector. The ancient works were destroyed by two short attempts to exploit, in the 18th and the 19th c., affecting both sectors. Both mining phases and sectors are characterised by two clearly different isotopic imprints (fig. 3).!

FIG. 3

15,69 15,69 15,69 15,69 15,69 15,70

38,50 38,55 38,60 38,65 38,70 38,75

Mines des Argentières MInes de Lacore

207 Pb / 204 Pb

208 Pb / 204 Pb

208

Pb/

²⁰⁴

Pb vs.

²⁰⁷

Pb/

204

Pb isotopic imprints for lead ore!

(Baron, unpublished)!

Argentières!

Roman era!

Lacore!

18th c.!

1400 1500 1600 1700 1800 1900 2000 cal AD

Charcoal kiln 20 Charcoal kiln 18(2)

Charcoal kiln 4 Charcoal kiln 1

Charcoal kiln 24 Charcoal kiln 7 Charcoal kiln 22 Charcoal kiln 26 Charcoal kiln 17(1)

Charcoal kiln 17(2) Charcoal kiln 13

1400 1500 1600 1700 1800 1900 2000 cal AD

According to Oxcal v4.2.3 Bronk Ramsey (2013); r:5 IntCal 13 atmospheric curve (Reimer et al 2013)

Ch. 13

1550 m

1596 m

Ch. 17

1454 m

1578 m Ch. 26

Ch. 22

1593 m Ch. 7

1486 m Ch. 24

1528 m Ch. 1

1553 m Ch. 4

1631 m Ch. 18

1617 m

Altitudinal transect of charcoal kilns (m. a.s.l.) Radiocarbon calibration curve of charcoal kilns (cal AD)

E xpansion of charcoal burning !

during the Renaissance and the Modern era!

The charcoal kilns are staggered between 1400 and 1650 m. asl. (fig. 1, 5), in a wooded area (high-growing coppices of Fagus sylvatica) of approximately 50 ha., with low density (0,6 charcoal kiln / ha).!

The

¹⁴

C AMS dates (only 10 as of now, fig.

4) suggest an expansion of charcoal burning during the 16th c. This period coincides with the functioning of the mouline of Castel- Minier into the valley below.!

These data also suggest the intensification of the charcoal production in this area during the Modern era, i.e. when the iron metallurgy in the Vicdessos peaked. They probably demonstrate that the medieval treaty iron/

charcoal exchange with the Vicdessos was still applicable. !

The project FODYNA is funded by the Observatory Human-environMent (OHM) Haut-Vicdessos (Labex DRIIHM, CNRS INEE), and has received support from both network MinAhm (Mine and Anthropisation of European and Transmediterranean high mountains) and laboratory GEOLAB (UMR 6042). !

* Co rr es po nd ing a ut ho r: v ane ss a. py @ uni v-t ls e2 .f r

1400 m 1500 m 1600 m

30 29 28

27 26

31 23 25 24

1 15 16

13 2 4 14

5 21

12 22 6

17 7 9 8

11 10 20

19 18

0 100 %

20 40 60 80

Fagus sylvatica Albies alba Bark

R. ferrugineum-Vaccinium

1650 m a.s.l.

0 cm

-10 cm

-20 cm

-30 cm

15th-16th centuries 17th-18th centuries 18th-20th centuries Legend

FIG. 5 Altitudinal profil of charcoal kilns and anthracological assemblages (Py, unpublished)!

T he issue of fir’s extinction!

The anthracological assemblages of charcoal kilns are dominated by beech associated with fir (fig. 5) for which the frequencies strongly decreased since the late Middle Ages (fig. 6). In the 16th c., charcoal burning contributed to the extinction of the fir but we must yet determine the roots of this change.!

FIG. 4 Radiocarbon calibration curve of charcoal kilns and altitudinal transect (Py, unpublished)!

Argentières (Aulus) - 1565 m asl.

Zones

AA-8 AA-7 AA-6 AA-5

AA-4

AA-3

AA-2

AA-1

0 20 40 0 ₁₀ 20 0 ₁₀ 20

%

Cultivated plants

& anthropochores Anthropic indicators Poaceae

Abies Fagus

Early Neo.

Mid.

Neo.

Late Neo.Chalc..

Bronze A.

Iron Ant.

Early M.A.

M.A.

Mod.

Chronocult. periods

Estimated age

5000 4000 3000 2000 1000 0 1000 1950 Cal.AD/BC

0

1

2

3

4

5

6 103yr

B.P.

FIG. 6

Synthetic!

Diagram of the Argentières

palynological record (Galop, 1998) !

Core

The combining of palynological, geochemical (comparison with atmospheric deposits sealed in lake and peat sediment), anthracological, dendro-anthracological and pedoanthracological data (ongoing for the most) should allow a detailed reconstruction of the woodland change between 1400-1700 m asl. and the impact of mining and ore processing activities in this high valley since the Antiquity.!

Galop, 1998. Galop, D., La forêt, l’homme et le troupeau das les Pyrénées. 6000 ans d’histoire de l’environnement entre Garonne et Méditerranée. Toulouse, GEODE.!

Py et al., 2014. Py, V., Ancel, B., Métaillé, J.-P., Baron, S., Cunill I Artigas, R., Prospection inventaire n°388. Commune d’Aulus-les-Bains (Ariège). Rapport de Prospection, Toulouse (ref. in ResearchGate).!