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You are here: Home Archive 1955 Über die Braunlehmrelikte des Atakor: (Hoggar-Gebirge, Zentral-Sahara)

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Über die Braunlehmrelikte des Atakor: (Hoggar-Gebirge, Zentral-Sahara)

DOI: 10.3112/erdkunde.1955.02.04
Year: 1955
Vol: 9
Issue: 2
Pages: 115-132

1. In the High Atakor, Central Sahara, a
subtropical layer of brown loam has been preserved which,
despite the present desert climate, has remained practically
2. In the paper a comparison is made between remains
of brown loam, which mostly occur on basalt, and soils
formed from basalt during recent times. Those used for
comparison are mainly the following: the tropical brown
loams of Fernando Poo (Gulf of Guinea), the brown earths
of Middle Europe and Northern Europe, the meridional
brown earths of Central Spain and the Canary Islands,
the recently formed soils of the Sahara and the high
mountain desert of the Teide (Teneriffe). At the same time
soils that have developed under known climatic changes
from brown earths remains are drawn upon for comparison.
3. By means of analysing the profile morphology, micromorphology
and the way in which a change of minerals
had occurred, it was found that the brown loam remains
are soil formations that took place during a pronounced
humid subtropical to tropical climate.
4. In addition to the brown loam remains, there are
further fossil red loams which in almost all cases are
covered by basalt sheets and thus in comparison with the
brown loams are easily recognised as being of greater age.
By comparative investigation of basalt red loams of other
areas, it can be stated that they are soils formed under a
humid tropical climate with pronounced hot dry-periods.
The red loams are of differing degrees of maturity; their
degree of laterization is small.
5. The time when the brown loam cover was formed
was most likely the latest great Pluvial period, since in
humidity this by far surpassed the later only moderately
humid periods.
6. The reason why the brown loam remains have changed
so little is to be found in the fact that the desert climate
in the High Atakor is of relatively recent date and further
that at this altitude it is less extreme and its consequences
are also less pronounced. After the tropical rain climate of
the last Pluvial period humid climates followed which,
though not allowing the formation of brown loam profiles
of the extreme type (Matadero-Variant), as found
here, nevertheless facilitated their preservation.
7. The fossil red loams are clearly older than the brown
loams but very likely are still of Pleistocene age. According
to the results of the paleo-pedological investigations this
time must also be postulated for the volcanism itself, since
a recent age cannot be assumed for the soil formations
which accompany it.

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