A Mesozoic foundation
The story of Huangshan's peaks begins in the Mesozoic Era, around 125 million years ago. Deep beneath the earth's surface, a massive body of molten magma pushed upwards and then cooled with extreme slowness. This process allowed large, coarse crystals of minerals like feldspar and quartz to form, creating the granite that characterizes the mountain range. This subterranean mass of granite, known as a batholith, was later exposed. Tectonic uplift, beginning around 65 million years ago, gradually raised the entire region, and millions of years of erosion stripped away the softer overlying rocks.
As the immense weight of the rock above was removed, the granite batholith expanded, a process called unloading. This expansion caused the rock to crack, creating a dense network of vertical joints and fractures. These fractures are the primary physical feature of the mountains, dictating how the rock weathers and creating the sheer cliffs and pillar-like peaks. The rock itself has very low porosity, meaning the fractures are the main pathways for water. Later, during the Quaternary Period, which began about 2.6 million years ago, the landscape was further sculpted. While the extent of glaciation is debated by geologists, frost weathering during cold periods likely sharpened the peaks and contributed to their dramatic shapes.