@article{SchulzJosephBaumhaueretal.1990,
  author    = {Schulz, Erhard and Joseph, Alain and Baumhauer, Roland and Schultze, Ekkerhard and Sponholz, Barbara},
  title     = {Upper Pleistocene and Holocene history of the Bilma region (Kawar, NE-Niger)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-86828},
  year      = {1990},
  abstract  = {A 42 m drilling was pertormed in the depresalon of Bilma, Xawar, NE-Niger. The sediment and pollen records show that after an initial deposition of dune sands there were repeated lake phases which terminated by desiccation and consolidation of spring mounds. The pollen record indicates a continuous presence of savanna vegetation. The record probably covers the period between the Upper Pleistocene and the Late Holocene. The climate was characterised by a monssonal summer rain regime giving effective rain fall of about 450-500 mm per year. Groundwater recharge was possible but estimates of the amount of water resources are difficult because of the karstic system of the escarpment and the nearly unknown hydrogeological situation.},
  subject      = {Pleistoz{\"a}n},
  language  = {en}
}
@inproceedings{Sponholz1993,
  author    = {Sponholz, Barbara},
  title     = {Holocene fulgurite formation in the southern Central Sahara (Niger)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56584},
  year      = {1993},
  abstract  = {Fulgurites (= natural glasses formed by lightning strikes to the ground) are indicators of thunderstorms (e.g. Julien 1901). The distribution pattern of fulgurites in the study area (Grand Erg de Bilma and Erg de Tenere between 11.5°E and 16.5° and 18.5°N) shows decreasing fulgurite concentration from south to north. The fulgurite sites are concentrated in the area of fossil dune complexes, where they occur topographically above palaeolimnic deposits in mid-slope position of interdune depressions.},
  subject      = {Geographie},
  language  = {en}
}
@article{Sponholz1994,
  author    = {Sponholz, Barbara},
  title     = {Silicate karst associated with lateritic formations (examples from eastern Niger)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53852},
  year      = {1994},
  abstract  = {Silicate and iron crust karst pits and sinkholes in eastern Niger are filled with reworked lateritic sediments or with unconsolidated palaeosoils and aeolian deposits. The fillings facies depend on the environmental conditions during deposition. Geomorphological and sedimentological studies on the karst fillings and the interpretation of various karst/filling associations allow an approach to the chronology of landscape development in eastern Niger plateaus.},
  subject      = {Geographie},
  language  = {en}
}
@article{Sponholz1990,
  author    = {Sponholz, Barbara},
  title     = {Silicate karst in eastern Niger - a geomorphological study},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-86846},
  year      = {1990},
  abstract  = {No abstract available.},
  subject      = {Niger <Ost>},
  language  = {en}
}
@article{SponholzBaumhauerFelixHennignsen1993,
  author    = {Sponholz, Barbara and Baumhauer, Roland and Felix-Hennignsen, P.},
  title     = {Fulgurites in the southern central Sahara, Republic of Niger and their palaeoenvironmental significance},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-63337},
  year      = {1993},
  abstract  = {The mineralogical and chemical characteristics of fulgurites ( = natural glasses forrned by lightning strikes to the ground) from the southern Centrat Sahara (Niger) are presented. The fulgurites are indicators of thunderstorms. The northernmost important fulgurite formation in the study area reached up to about l8°N, with decreasing fulgurite concentration from south to north. Their distribution pattern and the relative dating of their formation in relation to Iandscape history from the Late Pleistocene onwards (e.g., palaeolakes, palaeosols), and to Neolithic settlement reveals their value as palaeoenvironmental indicators. They indicate: (1) local palaeoenvironmental conditions depending on the topographical situation in a complex dune relief; (2) climatic change during the mid-Holocene from northerly rains to southerly rains; and (3) the northernmost Iimit of important thunderstorrns and rainfall activity since this time in the southern Centrat Sahara.},
  subject      = {Sahara},
  language  = {en}
}