Buses to Danxia National Geological Park (pronounced 'Dan-shee-uh') leave from the Zhangye West Bus Station.
The bus leaves every 60 minutes from 09:00 to 12:00, and 15:30 and 16:30.
There is no specific bus number, only Chinese characters and you can show this to the staff at the bus station:
Or just show them a picture of Danxia.
You can take the bus to Ice Valley area first, and after visiting you can take the pass-by bus to the Colorful Hills area and back to Zhangye.
Danxia National Geological Park Operating Hours:
6:00 - 20:00 (May 1 to Oct 10)
7:00 - 19:00 (other dates)