为砂泥岩、砾岩、砂砾岩。含有丰富的哺乳类化石,已发现有20多属种,主要类型有Hipparion hippidiodus,H. platyodus,Sinohippus zittele,Chilotherium anderssoni,Ictitherium hipparionum,Dinocrocuta gigantean,Chleuastochoerus stehlini,Palaeotragus microdon,Gazella dorcadoides,以及小哺乳动物化石 Prosiphneus licenti,P. sinensis,Paralactaga minor,Heterosmin...