from 345 million to 310 million years ago; increase of land areas; primitive ammonites; winged insects
双语例句
Yamansu Formation of the Lower Carboniferous comprises the main ore-bearing formation in the Xiaoshitouquan ore district. 摘要小石头泉矿区主含矿层为下石炭统雅满苏组第二亚组,火山穹隆及伴生断裂为主要的控矿构造。