The crystalline basement

Under extreme compressive stresses and pressure, marine sedimentary rocks were uplifted, creating characteristic recumbent folds, or nappes,

and thrust faults.[35] As the rising peaks underwent erosion, a layer of marine flysch sediments was deposited in the foreland basin, and the sediments became involved in younger nappes (folds) as the orogeny progressed. Coarse sediments from the continual

uplift and erosion were later deposited in foreland areas as molasse.[33] The molasse regions in Switzerland and Bavaria were well-developed and saw further upthrusting of flysch.[36]

The crystalline basement of the Mont Blanc Massif

The Alpine orogeny occurred in ongoing cycles through to the Paleogene causing differences in nappe structures, with a late-stage orogeny causing

the development of the Jura Mountains.[37] A series of tectonic events in the Triassic, Jurassic and Cretaceous periods caused different paleogeographic regions.[37] The Alps are subdivided by different lithology (rock composition) and nappe structure

according to the orogenic events that affected them.[8] The geological subdivision differentiates the Western, Eastern Alps and Southern Alps: the Helveticum in the north, the Penninicum and Austroalpine system in the centre and, south of the Periadriatic Seam, the Southern Alpine system.[38]

Compressed metamorphosed Tethyan sediments and their oceanic basement are sandwiched between the tip of the Matterhorn (Italian-Swiss border), which consists of gneisses originally part of the African plate, and the base of the peak, which is part of the Eurasian plate.[31]