534
Dupont
boundary ofthe Namib desert lies just south ofthe
southernmost core. Some indicator pollen types with
their source areas and principal transport mechanisms are given in Table I. The indicative value of
certain pollen in marine sediments is mainly derived
from the modern distribution patterns in marine
sediments (Hooghiemstra et al. 1986; Dupont and
Agwu 1991).
In addition to the pollen diagrams from each
core, a pollen spectrum from a surface sample is
shown (Fig. 9). Where we did not have a surface
sediment sample from the same site as the core
was taken, one as close as possible to the site was
selected. Surface sediment samples mostly cover
only the last few centuries. They can be compared
to the modern vegetation, whereby the strong impact of agriculture and human occupation especially
in the Mediterranean area, but also elsewhere, must
be kept in mind.
Due to coring techniques, the top sediments are
disturbed. As a consequence, the latest Holocene
is missing in all cores and some ofthem even lack
most of the Holocene. Sedimentary gaps exist in
the sequence from ODP Site 658 including the
lower part of Stage 3 and Stage 4 (Tiedemann et
a!. 1989) and in GIK16415, Stages 3 and 4 are
missing (Pflaumann 1986). Other gaps in the diagrams reflect sediments that are extremely poor in
pollen or in the case ofGIK16856 have turbiditic
sediments. Stratigraphic and age control of the
cores depend on the oxygen isotope stratigraphy
(Winn et a!. 1991; pflaumann 1986; Tiedemann
1991; Dupont and Weinelt 1996; Schneider et al.
1995; Jahns et al. 1998).
GIKI6004 (29°59'N JOo39'W)
The transect starts at 30 0 N just south ofthe Mediterranean vegetation zone and north of the Canary
Islands. The Mediterranean forest in the Moroccan mountains includes, among others, several oak
species, pine, ash, and ceder. Oak pollen dominates
the arboreals in many terrestrial Holocene sequences (e.g. Ballouche 1986; Bernard and Reille
1987; Damblon 1991; Lamb eta!. 1991). The transitional vegetation between the Mediterranean forest and the Sahara is formed by a steppe-like vegetation which is mainly represented by pollen from
Artemisia, other composites, and Ephedra, and to
a lesser extent by grass pollen from Stipa (Haifa
grass).
The sediments of Site GIK16004 show high
percentages of pine pollen (Hooghiemstra et al.
1992). Because ofthe large production of its aerodynamically well equipped pollen grains, pine is
generally strongly over-represented in marine pollen diagrams. During the LastInterglacial (and the
Holocene), the Mediterranean forest is mainly represented by Quercus (oak). The two surface sediment samples north ofthe site (32°N 10 0 W) show
somewhat higher percentages of Mediterranean
pollen, because of the samples' position nearer to
its source area. They are otherwise comparable.
The high percentages of pine pollen combined with
very low ones for the other elements of the Mediterranean forest during Stages 6, 4, and 2 are probably a reflection of enhanced transport by the NEtrade winds rather than a record of increased distribution of pines because, in terrestrial diagrams
of the High and Middle Atlas mountains, pollen
percentages of pine during glacial times are low and
those for Artemisia and Chenopodiaceae are high
(Lamb eta!' 1989, 1994).
GIK12392 (25°10'N 16°51 'w)
This core is situated south of the Canary Islands.
During interglacial periods, pine trees expanded on
these islands, as indicated in the marine pollen diagram with prominent maxima of pine pollen in combination with low percentages of elements from the
steppes (Agwu and Beug 1982). However, the pine
pollen maxima in Stages 4 and 2 combined with high
values of pollen from more arid areas (steppe and
desert) indicate enhanced trade-wind transport
(Hooghiemstra 1989).
The representation of the Moroccan Mediterranean forest is very low and probably insignificant
in the diagram. Also, the representation of the
Saharan-Mediterranean transitional steppes is considerably less than that off Morocco (GIKI6004;
30 0 N). Increases in relative values of grasses and
Cyperaceae during the "warm" periods of Stage 5
are probably attributable to a northward shift ofthe
Sahelian savanna. Those pollen grains would have
been transported by the northern branch of the AEJ
Dupont
boundary ofthe Namib desert lies just south ofthe
southernmost core. Some indicator pollen types with
their source areas and principal transport mechanisms are given in Table I. The indicative value of
certain pollen in marine sediments is mainly derived
from the modern distribution patterns in marine
sediments (Hooghiemstra et al. 1986; Dupont and
Agwu 1991).
In addition to the pollen diagrams from each
core, a pollen spectrum from a surface sample is
shown (Fig. 9). Where we did not have a surface
sediment sample from the same site as the core
was taken, one as close as possible to the site was
selected. Surface sediment samples mostly cover
only the last few centuries. They can be compared
to the modern vegetation, whereby the strong impact of agriculture and human occupation especially
in the Mediterranean area, but also elsewhere, must
be kept in mind.
Due to coring techniques, the top sediments are
disturbed. As a consequence, the latest Holocene
is missing in all cores and some ofthem even lack
most of the Holocene. Sedimentary gaps exist in
the sequence from ODP Site 658 including the
lower part of Stage 3 and Stage 4 (Tiedemann et
a!. 1989) and in GIK16415, Stages 3 and 4 are
missing (Pflaumann 1986). Other gaps in the diagrams reflect sediments that are extremely poor in
pollen or in the case ofGIK16856 have turbiditic
sediments. Stratigraphic and age control of the
cores depend on the oxygen isotope stratigraphy
(Winn et a!. 1991; pflaumann 1986; Tiedemann
1991; Dupont and Weinelt 1996; Schneider et al.
1995; Jahns et al. 1998).
GIKI6004 (29°59'N JOo39'W)
The transect starts at 30 0 N just south ofthe Mediterranean vegetation zone and north of the Canary
Islands. The Mediterranean forest in the Moroccan mountains includes, among others, several oak
species, pine, ash, and ceder. Oak pollen dominates
the arboreals in many terrestrial Holocene sequences (e.g. Ballouche 1986; Bernard and Reille
1987; Damblon 1991; Lamb eta!. 1991). The transitional vegetation between the Mediterranean forest and the Sahara is formed by a steppe-like vegetation which is mainly represented by pollen from
Artemisia, other composites, and Ephedra, and to
a lesser extent by grass pollen from Stipa (Haifa
grass).
The sediments of Site GIK16004 show high
percentages of pine pollen (Hooghiemstra et al.
1992). Because ofthe large production of its aerodynamically well equipped pollen grains, pine is
generally strongly over-represented in marine pollen diagrams. During the LastInterglacial (and the
Holocene), the Mediterranean forest is mainly represented by Quercus (oak). The two surface sediment samples north ofthe site (32°N 10 0 W) show
somewhat higher percentages of Mediterranean
pollen, because of the samples' position nearer to
its source area. They are otherwise comparable.
The high percentages of pine pollen combined with
very low ones for the other elements of the Mediterranean forest during Stages 6, 4, and 2 are probably a reflection of enhanced transport by the NEtrade winds rather than a record of increased distribution of pines because, in terrestrial diagrams
of the High and Middle Atlas mountains, pollen
percentages of pine during glacial times are low and
those for Artemisia and Chenopodiaceae are high
(Lamb eta!' 1989, 1994).
GIK12392 (25°10'N 16°51 'w)
This core is situated south of the Canary Islands.
During interglacial periods, pine trees expanded on
these islands, as indicated in the marine pollen diagram with prominent maxima of pine pollen in combination with low percentages of elements from the
steppes (Agwu and Beug 1982). However, the pine
pollen maxima in Stages 4 and 2 combined with high
values of pollen from more arid areas (steppe and
desert) indicate enhanced trade-wind transport
(Hooghiemstra 1989).
The representation of the Moroccan Mediterranean forest is very low and probably insignificant
in the diagram. Also, the representation of the
Saharan-Mediterranean transitional steppes is considerably less than that off Morocco (GIKI6004;
30 0 N). Increases in relative values of grasses and
Cyperaceae during the "warm" periods of Stage 5
are probably attributable to a northward shift ofthe
Sahelian savanna. Those pollen grains would have
been transported by the northern branch of the AEJ