Certain features of these engravings lead to the conclusion that they are of great age—geological changes had clearly happened after the designs had been made.
⇑ Translate the sentence above by Google ⇑
Related: geological
Prev: The hills are remnants of an earlier geological era, scraped bare of most soil and exposed to the elements.
Next: Archaeologists know that mounds such as these are the kinds of geological features that indicate the presence of ancient settlements.