ferrario m.f., brunamonte f., castelletti l., livio f., martinelli e., michetti a.m., historical...

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

Francesca.ferrario@uninsubria.it

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