We were able to knock off a chunk of Cataclasite from a large boulder embedded in a shallow creek; the 12-pound sledge hammer sent dangerous, bullet-like rock chips flying in all directions. The rounded boulder plus the hardness of the rock made specimen collection a formidable task.
These rocks are formed as a result of mechanical breakage and distortion that occur during earthly crustal movements. This photo shows clearly how extreme pressure can deform and fragment a metamorphic rock. Note the larger rock fragments surrounded by a fine-grained matrix and apparent melted deposits.
Copyright © 2006 William T. Hathaway.