Geographically, the Andes are a prime example of an “Andean-type” Folded mountain range formed at an oceanic-continental plate boundary. While they contain many volcanic peaks, their primary structure is a result of the intense folding and crustal shortening caused by the subduction of the Nazca Plate. This tectonic pressure has uplifted the sedimentary and igneous rocks into a series of high ridges and internal plateaus. Stretching over 7,000 kilometers, the Andes influence the entire continent’s geography, creating a rain-shadow effect that results in the Atacama Desert to the west and the lush Amazon basin to the east.

Block mountains or Horsts, are formed when large areas of the Earth’s crust are broken and displaced vertically along faults. The Sierra Nevada is one of the world’s most extensive block ranges. In Europe, the Black Forest and the Vosges represent a symmetrical geographical system where the crustal block between them subsided to form the Rhine Graben, leaving the edges standing as prominent highlands. These landforms are distinct from fold mountains because they are created by tensional or compressional faulting rather than the buckling of sedimentary layers, resulting in steep, cliff-like sides and relatively flat tops.

The Alps belong to the Tertiary mountain-building phase, making them “Young” in geological terms. Unlike the Appalachians or the Urals, which have been eroded into low, rounded hills over 250 million years, the Alps retain extreme vertical relief and sharp, glaciated peaks. Geographically, they represent the central core of the Alpine-Himalayan belt. Their youth is evidenced by their high elevation and frequent seismic activity. In contrast, the Aravallis are “Old” or “Relict” mountains that have been so heavily weathered that they now exist as mere stumps of their former height.