Boulder

In geology, a boulder is a large piece of rock fragment that is larger than 25.6cm or roughly 10.1 inches in diameter or with a size value less than -8 on the φ particle size scale with no upper size limit.

 References 

 Webster’s New International Dictionary of the English Language. Springfield, Massachusetts: G. & C. Merriam Company. 1913.
 "Boulder". Dictionary.com. Retrieved 24 August 2013.

 Citations 

 "Boulder". Collins English Dictionary.

 Other websites 

 Media related to Boulders at Wikimedia Commons

Category:Rocks