Holmes and Watson were investigating a murder at an archaeological dig-site

Holmes and Watson were investigating a murder at an archaeological dig-site

Holmes picks up several of the rocks and pebbles surrounding the murder victim. After a while, Holmes turns to his companion and says "I've cracked the case. The suspect was clearly murdered with a blow to the head by a rock, which then crumbled and scattered into pieces."

"How on Earth can you tell?" exclaims Watson.

"It's sedimentary, my dear Watson."