Geological Sheet no. 386 "Fiumicino" on a scale of
1:50,000
Geological sheet no. 386 “Fiumicino” is currently
being prepared. The part related to the sea area is being realized
according to an agreement between the National Geological Service
and the Lazio Region. The part related to the land area is being
realized directly by the Geological Service of Italy, Land Defence
Department, in collaboration with “La Sapienza”
University of Rome and the Geological Service of the Province of
Rome (for aspects concerning applied geology).
Sea area
This area of the Sheet includes the Tiber delta sedimentary
sequence that was deposited on top of the Würmian erosional
surface during the last glacial cycle.
The Sheet’s realization comprises the cartographic
representation of about 1,400 km of seismic records and bed samples
collected (with gravity bucket and core barrel) over the last 20
years by “La Sapienza” University of Rome. The
bathymetry was supplied by the Navy Hydrographic Institute
(Istituto Idrografico della Marina), with adequate details for this
type of study. Among other things, this enabled the relocation of
old seismic data that was adjusted according to more precise
parameters offered by the current sea station systems.
Sea maps were prepared according to rules provided by the
“New guidelines for the mapping of marine areas on a
scale of 1:50,000”. They represent the various
sub-environments deposited under the delta and their interaction
with the external and slope platform morphology and
sedimentation.
The good penetration of the seismic signal in these types of
sediments (except in limited areas where there are coarser deposits
or gas pockets) enables a geometric reconstruction of the
post-glacial deposit sequence of the area with a high vertical
resolution.
The application of sequential stratigraphy concepts, facilitated by
three-dimensional methods of analysis, enables the successful
matching of the geology of emerged and submerged areas, showing
their evolution in time.
Land area
This area of the Sheet has many points of interest related to the
presence of the Tiber River delta. Due to its relevance and
extension, it is the most important delta area in Italy after the
Po River delta. It also has large, highly anthropized areas.
Indeed, this area of the Sheet includes: the southern part of the
“Leonardo da Vinci” international airport; the
inhabited areas of Lido di Ostia and Fiumicino; several densely
constructed areas and the archaeological areas of Ostia Antica, the
Necropolis of Porto and the Traiano Port, covering almost 50% of
the total area.
These particular features required intense data collection
activities, which were carried out during the mapping campaign (on
a scale of 1:10,000). Samples were collected for
granulometric analyses (carried out at the laboratories of
APAT’s Land Defence Department). It became, above all,
necessary to integrate normal mappings with an analysis of aerial
photographs and an acquisition of survey stratigraphies (126 have
been collected until today).
A geological interpretation was made of aerial photographs of Italy
and of photograms realized by the Royal Air Force (RAF) during the
war, between 1943 and 1944. The latter revealed to be very useful,
since they referred to periods in which anthropization was still
very limited and was only a partial hindrance to the interpretation
of morphological elements.
This analysis led to the identification and mapping of different
dune bar systems and their variation in time, marking the different
evolutionary stages of both the coastal area and the shore.
The activity of collecting mapping stratigraphies, realized or
collected by public (APAT, Provinces, Regions, Municipalities and
ANAS) and private entities, is still in course. It is an essential
step to deepen our knowledge on the distribution and geometry of
subsurface bodies.
Mapping stratigraphies are digitalized and processed by means of
specific software which merge surface and subsoil data in order to
create a three-dimensional geological model of the area. This
provides an improved definition of the distribution and geometry of
geological bodies.
In addition, particular attention will be paid to environmental
emergencies in the delta and coastal areas. These are very
sensitive areas affected by phenomena such as overflowing,
subsidence, existence of submerged areas, coastal erosion and
possible sea-level rise, among others.