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Dry stone structures in a studied area, A-Ground level view (Photography, J.L. Rajot)., B-Satellite view (Google Earth, 28th Nov 08), C-Satellite image showing the dry stone structures with tiger bush, the natural vegetation of plateaus. The vegetated bands-with shrubs and trees-cover the dry stone structures (Satellite view) (Google Earth, 28 Nov 08)
Source publication
Les plateaux de la rive occidentale du fleuve Niger sont recouverts de lignes et de tas de pierres sèches alors que ces
surfaces tabulaires sont aujourd'hui dépourvues de toutes cultures. Le sol du plateau est constitué d'un horizon argilo-sableux
visible uniquement dans la zone où ces structures sont présentes. Elles témoigneraient d'un épierrage...
Contexts in source publication
Context 1
... stone structures were first observed in the field (Figure 1-A), then identified at metre-scale by high- resolution satellite imagery (Google Earth) (Figure 1-B). These structures were recorded in a non-exhaustive way on the main part of the lateritic soils in plateaus, mainly located on the west bank of the Niger River (Figure 2). ...
Context 2
... stone structures were first observed in the field (Figure 1-A), then identified at metre-scale by high- resolution satellite imagery (Google Earth) (Figure 1-B). These structures were recorded in a non-exhaustive way on the main part of the lateritic soils in plateaus, mainly located on the west bank of the Niger River (Figure 2). ...
Context 3
... structures were recorded in a non-exhaustive way on the main part of the lateritic soils in plateaus, mainly located on the west bank of the Niger River (Figure 2). Few people now live on the plateaus which are mainly covered with "tiger bush", i.e. alternating bands of vegetation and bare crusted soil (Clos-Arceduc, 1956;Leprun, 1992;Guillaume et al. 1999) (Figure 1-C). Temporary streams, tributaries of the river, incise those plateaus (250 ma.s.l.), along sandy valleys. ...
Context 4
... focused on this area as it is representative of west-bank landscapes. Dry-stone structures are open polygons of various sizes as well as round heaps ( Figure 1-B). They cover an approximate area of 23 km 2 , mostly near plateau boundaries. ...
Context 5
... parcel boundaries described in this study differ from the plots still in use seen on rocky slopes at Hombori (Mali) for example (Figure 10-A). They also differfrom fossilised ones like Tazbent in Algeria (Camps, 1960) (Figure 10-B). ...
Context 6
... parcel boundaries described in this study differ from the plots still in use seen on rocky slopes at Hombori (Mali) for example (Figure 10-A). They also differfrom fossilised ones like Tazbent in Algeria (Camps, 1960) (Figure 10-B). Mauritania's Tagant alone is organised into parallel bands on flat level areas but there is little information about it ) ( Figure 10-C). ...
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Citations
Recent global historical cropland modelling grossly underestimates the pre-colonial development of agriculture in the Americas and many parts of sub-Saharan Africa. Such models are usually developed by back casting from recent land cover, combined with environmentally deterministic algorithms. Historical geographers have been slow in responding to a new demand for a global synthesis. In this paper, a preliminary map of African agricultural systems dating to AD 1800 is presented. It forms a component of the project Mapping Global Agriculture and is based on the existing historical literature, observations by early travelers, archaeology and archaeobotany. It should be emphasized that the generated map should be considered preliminary.
Au sud-ouest du Niger dans les environs de Niamey, plusieurs milliers de bas fourneaux à usage unique ont été recensés. Une étude archéologique menée sur une trentaine de structures de bas fourneaux et de leurs scories a révélé la présence de quatre procédés de réduction du fer : trois de type scorie piégée et un de type scorie coulée. Les bas fourneaux à scorie piégée se différencient nettement par la morphologie et le volume de leur cuve. Les bas fourneaux à scorie coulée ont tous la particularité d'évacuer la scorie par de petits orifices creusés dans la cuve. L'écoulement de la scorie à l'extérieur de la cuve se fait soit verticalement soit latéralement. Selon les datations radiocarbone, l'activité métallurgique se développe dès le 2e siècle AD et s'intensifie jusqu'au 14e siècle. Au-delà, elle évolue et perdure jusqu'au milieu du 20e siècle. La production de fer par ces bas fourneaux est relativement faible, elle est principalement destinée au marché local.
