THE MEDITERRANEAN LOWER CRETACEOUS

PREFACE
The idea for this study arose several years ago, when the author had to investigate
the Bulgarian Lower Cretaceous in a wide (almost global) stratigraphie and palaeographic
panorama. Even at that time a picture emerged, representing —
figuratively speaking — an "Alpian-Himalayan" mixing of various processes and
phenomena, with different interferences in the concrete regions and provinces.
Parallel with this, there appeared the contours of definite trends of great significance
for the Early Cretaceous geological evolution of one of the most dynamic
areas in the Earth's crust.
In view of the level of present-day knowledge on the Lower Cretaceous in Bulgaria,
it may be assumed that its investigation over a wider area would contribute
to the further development of the theory and practice of Lower Cretaceous stratigraphy.
Another impetus for this difficult work is the practical lack of a generalization
of the Lower Cretaceous in world literature. After Kilian's synthesis in Lethaea
Geognostica (K i 1 i a n, 1907-1913) concerning the Lower Cretaceous in Southern
France, only Eristavi ( Эристави, 1962) has made an attempt at a generalization
of the Lower Cretaceous in the Alpine Zone, though his work is rather schematic.
The Mediterranean Region is part of the Tethys Ocean (Tethys Belt in palaeobiogeographic
sense of the term). The Tethys is known to have comprised vast ancient
marine aquatoria which crossed theMegagea from the Proto-Atlantic to the west,
to the Proto-Pacific to the east (S t i 11 e, 1946). It covered vast areas of Northwestern
Africa, Southern Europe, the Caucasus, Asia Minor, Iran, Afghanistan,
the Himalayas and Indo-China to the Caroline corner in the Proto-Pacific. The
Tethys Ocean was the conflict space between several lithospheric plates. It generated
tto Alpian-Himalayan Mountain Belt, while its fragments are the Mediterraneansea,
the Black Sea, the Caspian Sea, the Persian Gulf and the seas of the
Malayan Archipelago (B i j u-D u v a 1, 1974; В i j u-D u v a 1 et al., 1976).
The Mediterranean Region comprises Northern Africa, Southern Europe,
the Caucasus and Asia Minor. It is characterized by specific development of the
Lower Cretaceous, in contrast to the other adjacent regions and provinces (Volgian,
Boreal, Himalayan, Malgash, Andian). Various facies are developed in this region:
from deep-sea to continental. Rich fossil associations belonging to different groups
of organisms are found.
The present monograph is based on the results of the studies on the Lower
Cretaceous in Bulgaria, carried out by the author since 1957. In addition, between
1960 and 1984 the author had the opportunity to investigate and collect materials
from different countries in the Mediterranean Region (Algeria, France, Switzerland,
Italy, Yugoslavia, Greece, Hungary, Romania, Czechoslovakia, Poland and
the Soviet Union).
The study of the Lower Cretaceous over such a vast area came' up against many
difficulties, especially with respect to some countries where the series has been insuf-
5