The coastal scenery of the Northeastern Adriatic sea is widely interested
by caves and related coastal features, which are developed in correspondence
of geological weaknesses of sea cliffs. We present the preliminary
surveying of five partially submerged coastal caves cut in limestone
cliffs, relating the dissolutionally widened vadose karst voids and the present-
day forms. The analysis pointed out two well-defined morphological
zones inside the caves. The boundary between the zones roughly coincides
with the mean sea level. The submerged zone is mainly affected by
abrasion processes on the bottom and the lateral walls, while the emerged
zone is interested by karst processes and collapse of blocks from the roof.
Their effects produce a bell-shaped cross-section, in which the submerged
part of the caves is significantly larger than the emerged one.
Considering the tectonic behaviour of the area inferred from literature
the caves were flooded about 6 ka BP, when marine processes started
to shape their submerged part. Our results allowed, in particular, to
evaluate processes shaping the partially submerged coastal caves in the
Northeastern Adriatic Sea after the marine transgression. Considering the
very preliminary surveyed data, we suggest that the early phases of cave
evolution was mainly dissolutionally-controlled and produced the widening
of pre-existing joints or faults, as demonstrated by the occurrence of
karst features in the upper part of the caves. Recent evolution is instead
marine-controlled and the widening is mainly due to the overlapping of
marine processes effects on karst voids, since they are closely related to
the Late Holocene sea level rise.
