Corso Porta Reno, Ferrara (Northern Italy): a study in the formation processes of urban deposits

Abstract

Cremaschi M. & Nicosia C., Corso Porta Reno, Ferrara (Northern Italy): a study in the formation processes of urban deposits. (IT ISSN 0394-3356, 2010)
The city of Ferrara (Emilia Romagna, northern Italy) is located on the left bank of the branch of the medieval channel of the Po River,
the “Po of Ferrara”. This paper presents the results of the geoarchaeological study of the stratigraphic sequence exposed during
excavations in Corso Porta Reno, located at an intermediate position between the palaeo-Po alluvial ridge and the adjacent floodplain.
The area, also referred to as the “San Romano complex”, was excavated between 1981 and 1984, revealing an exceptionally well-preserved sequence, comprising occupation deposits and structural remains dated between the 8th and the late 13th century AD.
Geoarchaeological observations in the field and the micromorphological study of soil thin sections allowed the reconstruction of the
natural and anthropic processes involved in the formation of the site stratigraphic sequence. This is characterised by an alternating
succession of anthropogenic units (trampled domestic deposits, layers deriving from construction, destruction and/or refurbishing of
buildings, materials from decantation within anthropic structures) and of natural alluvial deposits (light-coloured sandy layers often
showing cross laminations, linked to a crevasse-splay context active during the human dwelling). The waterlogged nature of the site,
the rapid rate of sedimentary accretion, and the sealing of the sequence due to the construction of a brick house in the 13th century
avoided the well-stratified deposit to be heavily homogenized by bioturbation or reworked by later human activities. The model envisaged at Corso Porta Reno could partly explain the strong vertical accretion of urban deposits during the Middle age and provide a possible mode of formation for thick “Dark Earth” sequences in medieval cities in active alluvial settings.