203751
The site is of special interest for the rock exposures of the Grey Grit Formation of the Upper Old Red Sandstone ; these exposed rocks span the boundary between the Carboniferous and Devonian periods of geological time , approximately 360 million years ago .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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