(Fig. 9) Pollen analysis of sediment core GIK16017-2

The improved understanding of the pollen signal in the marine sediments offshore of northwest Africa is applied to deep-sea core M 16017-2 at 21°N. Downcore fluctuations in the percentage, concentration and influx diagrams record latitudinal shifts of the main northwest African vegetation zones and characteristics of the trade winds and the African Easterly Jet. Time control is provided by 14C ages and 180 records. During the period 19,000-14,000 yr B.P. a compressed savanna belt extended between about 12 ° and 14-15°N. The Sahara had maximally expanded northward and southward under hyperarid climatic conditions. The belt with trade winds and dominant African Easterly Jet transport had not shifted latitudinally. The trade winds were strong as compared to the modern situation but around 13,000 yr B.P. the trade winds weakened. After 14,000 yr B.P. the climate became less arid south of the Sahara and a first spike of fluvial runoff is registered around 13,000 yr B.P. Fluvial runoff increased strongly around 11,000 yr B.P. and maximum runoff is recorded from about 9000-7800 yr B.P. Around 12,500 yr B.P. the savanna belt started to shift northward and became richer in woody species: it shifted about 6° of latitude, reached its northernmost position during the period of 9200-7800 yr B.P. and extended between about 16° and 24°N at that time. Tropical forest had reached its maximum expansion and the Guinea zone reached as far north as about 15°N, reflecting very humid climatic conditions south of the Sahara. North of the Sahara the climate also became more humid and Mediterranean vegetation developed rapidly. The Sahara had maximally contracted and the trade winds were weak and comparable with the present day intensity. After about 7800 yr B.P. the southern fringe of the Sahara and accordingly the savanna belt, shifted rapidly southward again.

General agricultural export and trade situation [microform] : hearing before the Committee on Agriculture, House of Representatives, Ninety-seventh Congress, second session, March 9, 1982.

"Serial no. 97-HHH."

Great Lakes Protection Act of 1981 [microform] : hearings before the Subcommittee on Natural Resources, Agriculture Research, and Environment of the Committee on Science and Technology, U.S. House of Representatives, Ninety-seventh Congress, first and second sessions, December 15, 1981, March 9, 1982.

"No. 120."

American technology transfer and Soviet energy planning [microform] : hearings before the Subcommittee on Investigations and Oversight of the Committee on Science and Technology, U.S. House of Representatives, Ninety-seventh Congress, first and second sessions, December 10, 1981, February 9, 1982.

"No. 122."

The human factor in innovation and productivity [microform] : hearings (including the record of a seminar sponsored by the American Association for the Advancement of Science on July 28, 1981) before the Subcommittee on Science, Research, and Technology of the Committee on Science and Technology, U.S. House of Representatives, Ninety-seventh Congress, first session, September 9, 10, 11, 15, 16, 17, 1981.

"No. 51."

Aviation safety research [microform] : hearing before the Subcommittee on Investigations and Oversight and the Subcommittee on Transportation, Aviation, and Materials of the Committee on Science and Technology, U.S. House of Representatives, Ninety-seventh Congress, second session, March 9, 1982.

"No. 85."

Development of WEB pipeline in South Dakota [microform] : hearing before the Subcommittee on Conservation, Credit, and Rural Development of the Committee on Agriculture, House of Representatives, Ninety-seventh Congress, first session, on H.R. 4347, September 9, 1981.

"Serial no. 97-Y."

Extension service oversight [microform] : hearings before the Subcommittee on Department Operations, Research, and Foreign Agriculture of the Committee on Agriculture, House of Representatives, Ninety-seventh Congress, second session, February 17, March 9 and 10, 1982.

"Serial no. 97-EEE."

Farm Crisis Act of 1982 [microform] : hearings before the Committee on Agriculture, House of Representatives, Ninety-seventh Congress, second session, on H.R. 6274, May 25 and June 9, 1982.

"Serial no. 97-TTT."