In the Jizhong Depression, the Cenozoic igneous rocks, distributing within the Eogene strata, trend to be younger in age but increase in thickness, and in area from the south toward the north.

• 新生代火成岩分布于下第三系地层中,为基性的喷发岩或侵入岩,由南向北,时代变新,厚度及分布范围增大。