Yardan landforms are unique geological formations found in arid areas around the world. They are formed through a combination of geological and external factors, including lacustrine sedimentary strata and erosion from powerful directional winds and flowing water.

In arid regions, lakes often experience repeated cycles of water in and water out, resulting in layers of mudstone and sandy soil that are superimposed up and down. Wind and flowing water can erode the loose sandy layers but have a limited impact on the hard mudstone and gypsum cement layers.

However, the dense mudstone layer is not indestructible and will eventually crumble due to the drastic temperature changes in the desert.

As the sandy layer is carried away by wind and water, grooves are formed, while the covered mudstone layer remains stable, forming long mounds that gradually evolve into Yardan landforms.

The external factors in the formation of Yardan landforms are generally considered to be strong prevailing winds, but this is not always the case.

For example, in the eastern section of the Achik Valley, the Sanlong Sha Yadan is oriented south-east, perpendicular to the prevailing northwesterly winds, and in the same direction as the mountain flood flow, indicating that floods play a dominant role in this part of the Yadan landscape.

In other cases, Yardan landforms are formed by the combined action of wind and flowing water.

It is important to note that Yardan landforms do not always have a uniform red color like the Danxia landforms. Instead, they can present a variety of colors such as gray-green, earthy yellow, purple-red, and more.

Deserts are the most typical wind-formed landforms. Strong winds raise sand and dust from the ground, and when the wind weakens, the dust falls back down. Over time, the dominant wind accumulates more sand and dust in a specific area, eventually forming a desert.

Typical Yardan landforms are found on dry lake bottoms, river terraces, or lake terraces in arid areas. They are mostly composed of unconsolidated or semi-consolidated sand and gravel rocks.

Persistent directional winds blow along the dry fissures or tectonic fractures, causing flat and poorly consolidated lake bottom sediments to gradually form a series of irregularly arranged fin-shaped ridges and wide shallow grooves slightly parallel to the main wind direction.

These ridges can be tens of centimeters to tens of meters high, while the grooves can be several meters wide and tens to hundreds of meters long, with some being over a thousand meters long.

Most of the inner grooves are filled with quicksand. Due to long-term wind erosion, individual ridges are often fin-shaped or streamlined, with the windward side usually rounded and the leeward side elongated or scattered.

The surface of the filled quicksand between the grooves usually retains obvious wind-formed corrugations.

Other wind-eroded landforms include wind-eroded caves or niches, wind-eroded pillars, wind-eroded castles, and more.

However, it is important to note that almost all wind-erosion-related landforms are generally referred to as Yardan landforms in many articles or travelogues today.

Yardan landforms are unique and fascinating geological formations that are formed through a combination of geological and external factors, including lacustrine sedimentary strata and erosion from powerful winds and flowing water.

They can present a variety of colors and are typically found on dry lake bottoms, river terraces, or lake terraces in arid areas.