How Are Colorful Hills Formed?

During the Cretaceous period, the colored hilly area was a large lake. Due to the deposition of different metal elements, the sand and mud layers formed at the bottom of the lake presented different colors. Later, as the climate became colder and drier, the original Great Lake dried up. With continuous compaction, dehydration, and consolidation, these sand and mud layers originally deposited at the bottom of the lake formed hard sand and mud layers. After that, uplift and compression occurred here, and layers of horizontal sandstone and mudstone were lifted to relatively high positions and became inclined or curved. These exposed rock layers were exposed to the sun, rain, wind, freezing, and thawing, gradually forming low small hills, which are the colored hills we see.