The Quaternary Period in Switzerland

Abstract

The evolution of the Swiss landscape during the Quaternary Period over the past 2.6 million years is controlled by multiple glaciations and deglaciations with at least 15 drastic environmental changes between glacier advances (with yearly average temperatures of –16° compared with today) and warm phases (with yearly average temperatures of +2° compared with today). During the Most Extensive Glaciation (MEG) several hundred thousand years ago, Switzerland was almost completely ice-covered with the exception of the area around Basel and the most external parts of the Jura Mountains. During the warmest interglacial periods the glaciers were, most likely, completely gone. The feeding mechanism for the inner-alpine ice accumulation was a southerly (foehn) circulation. Vegetation cover during interglacials was comparable to today except for the Last Interglacial when Fagus (beech) was missing and during at least one older interglacial when a Fagus/Petrocary-forest was growing in theCentral Plateau. The age for the deep valley erosion in the northern Alpine Foreland is several millions of years younger than in southern Alpine Insubria.