In northwestern China lies a hilly landscape with natural, colorful striped patterns running across its surface. The area is known as Zhangye Danxia, a rock formation displaying a range of varied color gradients.
Geographically, the hills sit at the northern foothills of the Qilian Mountains. The site falls under the administrative jurisdiction of Linze and Sunan counties within the prefecture-level city of Zhangye, Gansu Province. The entire landform spans a total area of 322 square kilometers.
The park's main territory is divided into several scenic areas. The Linze Danxia area serves as the central hub, located 30 kilometers west of downtown Zhangye.
Meanwhile, the Binggou Danxia area covers 300 square kilometers north of the Liyuan River, with elevations ranging from 1,500 to 2,500 meters above sea level. The Sunan Danxia area completes the territorial division on the southern side.
The Formation Process of Sedimentary Rock Layers
The formation of the vibrant layers at the Zhangye Danxia hills required an extraordinarily long period. The development of the sandstones and mineral deposits spanned over 24 million years, stretching from the Cretaceous period to the Tertiary era.
In ancient times, the Gansu region was a vast yet shallow lake basin. Surrounding rivers continuously carried deposits of sand, mud, and gravel into the basin. The sedimentary materials accumulated at the bottom of the water over time, eventually hardening into stacked rock strata.
Each layer contains a distinct mineral composition. Variations in layer thickness and grain size were influenced by shifting water discharge and changing prehistoric climatic conditions.
Subsequent tectonic movements altered the position of the originally horizontal rock strata. The same tectonic forces that built the Himalayan mountains tilted the sedimentary rock stacks in Zhangye. Subterranean pressure pushed the folded land upward, exposing ancient rock layers to the surface.
The Impact of Weathering on Color Gradients
The colorful stripes on the hillsides are the product of chemical reactions and oxidation between rock minerals and atmospheric elements. The reddish-brown layers originate from hematite or iron oxide reacting with water and air.
Other shades stem from secondary minerals deposited differently within each layer. Limonite compounds create bright yellow hues, while chlorite and chalcedony produce pale green to bluish-gray tones.
Rainwater erosion and harsh desert winds gradually eroded the softer rock layers. Tens of millions of years of weathering sculpted steep cliffs, sharp pillars, and narrow ravines, revealing the colorful strata on the surface.
The appearance of the rock colors is also influenced by humidity levels. Following rainfall, moisture absorbed by the ground surface makes the color contrasts appear noticeably richer and sharper
Protecting the Fragile Landscape
Despite their striking appearance, the sandstone and mudstone deposits at Zhangye Danxia are extremely fragile. Repeated foot traffic can rapidly erode the delicate sediment surfaces and disrupt the crisp color lines above them.
Its vulnerability has led park management to strictly regulate movement on bare ground. All access is redirected to a network of wooden boardwalks elevated along the contours of the hills.
The wooden pathways keep the underlying rock surfaces completely untouched. At strategic points, the boardwalks widen into viewing platforms to prevent visitor crowding on narrow cliff edges.
The construction of the wooden corridors was carried out in phases across the Linze and Binggou areas. Specifically in the Binggou area, management expanded the boardwalk network in 2014 to connect new observation points along the rock valleys.
As part of broader management efforts, China's Ministry of Land and Resources formally designated the area as a National Geopark on June 16, 2016. Furthermore, UNESCO designated the site as a UNESCO Global Geopark in 2020.
Reference:
Liu, X., Liu, Z., Guo, H., Li, P., Li, Z., Lue, B., & Zhao, G. (2012). Paleosol characteristics of Zhangye Cretaceous colourful "Danxia" and its sedimentation environment analysis. 3249. Abstract from International Geological Congress (34th : 2012), Brisbane, Queensland, Australia.
