palaeozoic stratum

例句：

1. 1. Thepaleozoic stratum is a key to unlocking the secrets of Earth's past.
   古生代地层是解开地球过去秘密的关键。
2. 2.The paleozoic stratum contains fossils that are millions of years old.
   古生代地层包含数百万年前的化石。
3. 3.The paleozoic stratum is an important source of minerals and metals for modern industry.
   古生代地层是现代工业的重要矿物和金属来源。