The figurative language device that was used in the bolded portion of the sentence is:
Personification is a form of speech that is used when the qualities of living things are used to describe non-living things. In the bolded part of the sentence, the rock was described as frowning.
This is usually the attribute of human beings that is now being assigned to a rock.
Learn more about personification here:
https://brainly.com/question/1013597
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