Celebrated on September 1st
Along with the ubiquitous yellow “Smiley” that gets a nod in Forrest Gump (1994) and “mood rings” which purported to contain a magic stone that changed color depending on your mood, the “Pet Rock” was one of the crazier fads of the decade. Funny thing is, people loved them — and they made their inventor a millionaire.
Rocks are solid and impossible to break with your hands. You can use a hammer or sledgehammer to break them apart though. Can you believe that water or plants can break a rock apart? Yes, water can break rocks apart by a freeze, thaw cycle. Water will seep into cracks in rock and sit there. Then overnight if the water freezes it expands (when water freezes it expands). This expanding action of water can break apart large rocks or boulders and over time the crack gets bigger and bigger. Plants can break rocks using their roots. The roots can sneak into cracks and slowly over time grow larger, causing the crack to get bigger.
Technically, the oldest known rocks existing on Earth are not from Earth at all, but are instead of extraterrestrial origin . Moon rock samples collected during the Apollo missions have been dated to about 4.5 billion years, besting our oldest terrestrial rocks by a few hundred million years.