ferrario m.f., brunamonte f., castelletti l., livio f., martinelli e., michetti a.m., historical...
TRANSCRIPT
Historical shoreline evolution and the Roman Harbour in the Como urban area: results from
stratigraphic and geotechnical analyses
Ferrario M.F., Brunamonte F., Castelletti L., Livio F., Martinelli E., Michetti A.M. & Motella S.
Università dell’Insubria, Dipartimento di Scienza e Alta TecnologiaVia Valleggio 11, Como
Medolo Group (pelagic
limestones, EarlyJurassic)
Gonfolite Group (conglomerates
and sandstones, Oligo
– Miocene)
GonfoliteBackthrust
Stratigraphic database
Piazza Verdi
Piazza Verdi drillings- 2 boreholes (65 – 70 m)
- Physical parameters- Shear tests, triaxial tests
- Permeability tests- Macroremains and
palynological analyses- Gamma-Ray analysis
- Carbon dating
Subsidence
• Natural: soft sediments (few mm/y)• Anthropic: ground water overexploitation (up to cm/y)
• Increased risk of inundation• Building damages
Photo by Valerio Comerci
LGM - Maximum extension of Adda glacier and water outflow
Modified afterBini et al., 1993
Lateglacial
270 m asl
220 m asl
1st appearance organic substanceca. 18 kyr BP
215 - 220 m asl
Coastline (18.000 BP)
Delta progradation
Proto-historic settlements
Shoreline
I century BC
City walls (I century BC)
Archaeologicalfindings: Roman
quay
Archaeologicalfindings: ship remains
(Piazza Mazzini)
Prehistorical drainage network
Drainage modified by the Romans
Archaeological findings
In 1964, in Piazza Mazzini a marble block and shipremains were discovered at 4,60 m below the groundsurface.
Shoreline
1858
1722
1871
2013
I century BC
City walls (I century BC)
City walls (IV-V century AD)
Historical coastline position
Catasto Teresiano, 1858
Catasto Teresiano, 1898
Piazza Cavour
1997 campaign- 10 drillings (60 m deep)
- 5 CPTU- lab tests
2013 campaign- 3 drillings (30 – 40 m deep)
- 2 drillings (10 m deep)- 10 DPSH
- cross-hole seismic tests
- In progress: radiocarbondating, plant macroremains and
diatoms analyses
Pile-dwellings
Gas-emission features
Leather tiers (depth: 13 m)
The cross-disciplinary integration of the variousdatasets enables to:
- Identify an organic silty layer ca. 2-4 m thick, with very poor mechanical
properties, related to a closed low-energyenvironment, such as a sheltered harbour or a
dock;
- Sparse reworked bricks fragments suggest anhistorical age;
- Reconstruct the isopachs of this layer
Geologic section
SW NE
wn = 60 – 90 %LL = 55 – 70 %
Qc = 0,2 – 0,5 MPa
SE NW
Man-made fillings
Organic siltsAlluvial sands
Organic clayey silts
Conclusions
A multidisciplinary approach, involving data coming from both geology and
archaeology, can lead to a more accurate knowledge of an area, thus allowing to
understand present-day natural and anthropic dynamics and to better plan
future urban development.
Thank you
This research was realized in collaboration with Comune di
Como and Georicerche srl