The extraordinary diversity of landscape types and forms that makes up the natural environment of Switzerland is attributable, on the one hand, to the large-scale geological and tectonic situation (e.g., alpine nappe structure, folds of the Jura). The topographic division of Switzerland into 3 regions: the Alps (approx. 60% of the area), the Midlands (30%) and the Jura (10%) mainly reflects the alpine mountain formation of the Tertiary (65-2.4 million years ago). On the other hand, geomorphological processes have been primarily responsible for the emergence and individual evolution of the surface formations.
Geomorphology encompasses all those processes which in a typical manner shape the land surface and dynamically re-form it, for example, through the effect of water (rivers, streams; fluvial or karstic processes); of ice (glaciers, permafrost; glacial, periglacial); of wind (aeolian); and of gravity (e.g., slumping, rockslides; denudational, gravitational). In geomorphological processes, there is a constant displacement of material via sediment transport. Characteristic process areas (e.g., pro-glacial and karst regions) with typical individual features (e.g., moraine ridges, dolines) evolve over time. It is the task of geomorphology to identify, interpret and evaluate geomorphological formations and processes, for example, with regard to their risk to the human population (natural hazards, e.g., those caused by debris flows, rockslides or slope slipping).
The Ice Age (Quaternary Period: from about 2.4 million years ago until today, lower limit still debated) is of critical importance for modelling the current wealth of landforms. The original tertiary relief was reshaped from time to time in the glaciated regions during the Ice Ages (drumlin fields of the Midlands), and in the ice-free expanses (e.g., loess deposits near Basel) during a series of cold and warm climatic cycles.
The most visible shaping of the overall landscape can be traced back to the last Ice Age, the Würm glacial period (maximum phase 25,000 years ago) and the subsequent melting period of the glaciers (e.g., emergence of alpine marginal lakes, debris avalanches, erosion of the valley slopes, formation of alluvial cones and deltas). Nowadays it is human activities, much more than Nature, which alter, and sometimes irreversibly damage, the landscape and natural environment (e.g. through excavations and landfills, housing settlements, river straightenings, gravel pits, ski slope preparation, waste depositories, etc.).