The peaks of Alps

The Alps are a complex system of lower fold mountains and high crystalline massifs. The lower mountains are largely limestone and other sedimentary rocks, while the higher peaks are composed of a crystalline, magnesium-rich rock known as dolomite. The Dolomite range in northeast Italy, with its imposing jagged pinnacles and sharp ridges, takes its name from this rock. The Alps were formed during the Oligocene and Miocene epochs as a result of pressure exerted on the Tethyan geosyncline (sedimentary deposits in the ancestral Tethys Sea), as its strata were squeezed against the stable Eurasian landmass by the northward moving African landmass. The squeezing action formed the folds (nappes) that rose out of the sea and pushed northward, often breaking and sliding one over the other to form gigantic thrust faults.