Geography Reference
In-Depth Information
4.4. Sighting tracks
Some sighting tracks (sometimes identified by a number and a letter) are clearly visible, in
particular in L map (Figure 8) and occasionally in P map. These tracks are preserved in sea
areas lying between the Po delta and the continental coast reaches in the northern and
southern part of the delta lobe. They try to define the correct distance existing between
selected points lying on the fast-prograding delta coast and well-visible landmarks lying on
the opposite coastal domain, e.g.
Mesola
defense towers and
Chioggia
bell towers. The length
of the longest tracks is about 10 km, a plausible value for field surveys in marine
environment free of the vegetative mantle (thus characterized by a good inter-visibility of
the points).
This kind of information could suggest the author's need to control the existence of gross
errors in the conclusive survey phase.
Figure 8.
Examples of sighting tracks visible in L map.
4.5. “Lost landmarks”
Other signs of unclear value are visible in F map. They are not preserved in today
landscape, thus they should have not been true
landmarks
(Figure 9): for this reason we
prefer to use the term
lost landmarks
for their identification. They consist in few small crosses
and a large one located at the diffluence point of two river branches of the
Po di Levante
. The
large cross was probably a real reference-point as this object gave its name to a salt marsh
(
Polesine de la Crose
) and to a still preserved building. The small crosses are located in desert
areas of the E and SE realms of the delta lobe, along a red double curvilinear track. The
meaning of the curvilinear tracks has been deduced from the comparison with another map
of the same area dating back to the year 1608: they define the boundaries of the lands
confiscated by the Venice Government in 1588.
This class of evidences highlights how difficult the ancient land surveying was, due to
lacking of tall and fixed benchmarks in high-speed changing areas. On the other hand, it
highlights how much important, from an economic point of view, those new generated
areas were for the local government, thus suggests a possible reason to start the survey
