They can take rocks within the caves, and they can slice them and look at the layers within with rocks, much like the rings of a tree, and they can count back in history and learn about the climate on our planet at very different times.
他们可以采集洞穴里的石头， 把石头切割开，逐层研究， 就像在读树的年轮， 他们能够知道石头的历史 和地球气候变化的不同时期。