From April 12 to 19, 1984, dust was [Windom, 1975; Chester et al., 1979; Sarnthein et collected by cascade impactor on Fuerteventura al., 1982] and, probably, to the mineral feeding Island, 100 km from the Saharan coast. The sam-of marine plankton. The dust outbreaks from ples were analyzed by X ray fluorescence spectro-northwestern Africa to the middle Atlantic and metry (elemental composition), by X ray diffrac-Western Europe have been much less studied. The tion (mineral constituents), and by scanning only samplings were carried out during oceanic electron microscope (SEM) and energy dispersive X cruises [Chester and Johnson, 1971; Parkin et ray analyzer (EDXA) examination (shape, surface al., 1972] and the results were compared to the features, and mineralogy of particles), with the marine sedimentation [Tetzlaff and Wolter, 1980; aim of determining the possible source areas of Sarnthein et al., 1982]. On the other hand, the the dust. On the scale of dust clouds, another fallout on the islands was not considered, except method allowed us to define the displacements of in a short note about the sampling of dust on the dust: using remote sensing (METEOSAT II, Tenerife island [Fernandez-Navarro, 1921] and National Oceanic and Atmospheric Administration another about the dust effects upon the under-(NOAA)) and computing trajectories for any star-ground water chemistry in the Gran Canaria ting or ending point at any time. These various [Logan, 1974]. methods gave complementary results and pointed A research project, supported by the French out two successive episodes of dust with two Centre National de la Recherche Scientifique different continental origins. The first ori-(CNRS), started with the purpose of characteriginated from a nearby source in the Souss plain zing Saharan dust [Coud•-Gaussen, 1982, 1984; (southern Morocco) and was characterized by very Coud•-Gaussen and Rognon, 1983]. Fuerteventura fine quartz particles. The second drifted above Island (eastern Canaries) is a particularly intemore remote calcareous regions. This study allows resting area for this study because aeolian parus to show how different methods can be used to ticles have been encountered in various silty characterize dust and to find the source areas. deposits of surface formations: desert quartz, The results suggest some general questions about allochthonous minerals, feltlike grains of fithe occurrence of coarse particles in the atmos-brous clays, etc. [Chamley et al., 1987]. Relaphere and their role in the atmospheric depositing to this project, dust samples were collected tion flux budget. from April 12 to 19, 1984, on Fuerteventura Island. This island is 100 km from the Saharan Recherche Scientifique, Universit• Pierre et study on the year 1979 from the imagery given by Marie Curie, Paris, France. the GOES East and METEOSAT satellites [01iva et 2 Laboratoire de Physico-Chimie de l'Atmosph•-al., 1983].
