THE MEDITERRANEAN LOWER CRETACEOUS

Part Three
GENERALIZATIONS AND CONCLUSIONS
IV. SRATIGRAPHIC OUTLINE
1. BERRIASIAN
The Berriasian is widespread in the Mediterranean Region. It is represented by
varied marine facies, in some places by continental formations of Purbeckian or
Sahara type as well.
A gradual lithological transition from Tithonian to Berriasian sediments is
observed in most regions. This continuity is disrupted in some places by local tectonic
and / or palaeogeographic phenomena. The absence of Berriasian sediments
in some regions is the result of stable uplift with considerable duration.
In the southwesternmost part of the area (the Cape Verde Islands) the Berriasian
is represented by pelagic limestones with flint, formed in the continental
base of Southwestern Africa. It also comprises part of the slightly metamorphosed
limestones.
Further north, in the continental foothills of the Moroccan Meseta, the Berriasian
comprises part of the thick complex of Lower Cretaceous flysch, in the marl
associations of which characteristic Nannoconus and foraminifera associations have
been found.
These sediments from the southern part of the North Atlantic Ocean are in contrast
to the shallow-sea sediments of the stage in the Agadir Basin in Morocco. Carbonates
with typical neritic fauna are developed there at the base of the Berriasian,
followed above by clayey limestones and marls with ammonites.
The Agadir section demonstrates a gradual deepening and entrainment of new
areas from the continental margin belo.w the ocean waters during the Berriasian.
Deep-sea clayey limestones, rich in radiolaria, nannoplankton, calpionellids
and aptychi are developed in the north, in the coastal strip of the Moroccan
Reef.
The spatial distribution of the facies of the Berriasian sediments in Southwestern
Africa and in its continental margin is determined by a number of local factors,
though a regular shallowing of the basin from west to east and from north to south
is observed, whereby continental facies are reached ("continental intercalaire"
after Kilian).
Berriasian sediments are widespread in Algeria and Tunisia.
In the High Plateaux the Berriasian is connected with neritic facies. Terrigenous
sediments predominate in the western part of the Plateaux, whereas terrigenouscarbonate
deposits begin gradually to be imposed in the east-northeast. In the southern
part the flysch is predominantly carbonate, whereas terrigenous components
prevail to the north of Chelif river. The transition between the neritic facies of the
High Plateaux and the deep-sea deposits of the Tellian Atlas is observed well in the
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