Deep soils on stable or slowly surfaces time versus climate as soil-forming factors. The Ferretto-type Paleosol, a case study: the Crocetta profile (Gazzola, Piacenza, Northern Italy)

Abstract

The Crocetta soil profile, which is typical of the Ferretto paleosols, is studied in details on the ground of the field characteristics, heavy minerals composition and micromorphological features. The profile, 12.5 m thick, is located on the upper terrace of the river dating to the Early Pleistocene. The parent material is gravel overlied by loess sheets. Three functional zones have been distinguished in the profile. - Slowly aggrading zone, composed by superposed soil horizons developed in loess sheets that were deposited since Middle to Lower Pleistocene. - Relict zone including relict features originated in a wetter and warmer pedoclimate during oldest phases of the soil development. - Gravitative zone, still active which begun to develope since the Middle Pleistocene through decalcification, argilluviation and rubifaction. The Crocetta profile is the result of a complex set of soil forming processes which acted for a long while, without any important break: in this sense it can be regarded as a Vetusol. However, the oldest part of the profile still includes relict features, originated in a different pedoclimate, which are being dissolved by present soil forming processes.