Rock Detective Key

After the big storm, the creek bed was full of new rocks. Little Thunder carried a bucket of them up to the shed.

"Look at all these! What are they?"

Suzy pulled a card off the shelf. "This is a rock key. A real geologist's tool. You answer yes or no questions, and it leads you to the name."

Little Thunder picked up a grey rock full of tiny holes. "This one is super light."

"Question one," read Spike. "Does it have holes or bubbles?"

"Yes!"

"Then go to question four. Does it float in water?"

They dropped it into the trough. It bobbed on top!

"Pumice," said Suzy. "It's an igneous rock. It formed when hot melted rock from a volcano cooled down really fast, trapping gas bubbles inside."

Next was a rock with stripes, like a layered cake.

"Does it have layers?" read Spike. "Yes. Does it crumble or feel sandy? Yes. Sandstone! A sedimentary rock, made from sand pressed together over millions of years."

Nairobi the cow peered into the bucket. "Uluru is made of sandstone like that. Well, a kind called arkose. It glows red because of the iron in it, a bit like rust."

The last rock was shiny and sparkly, with wavy bands.

"Was it squeezed and heated deep underground?" read Little Thunder slowly. "How would I know that?"

"Look at the bands," said Suzy. "That's a clue. It's gneiss, a metamorphic rock. It used to be a different rock, but heat and pressure changed it."

Little Thunder lined them up proudly. "Igneous, sedimentary, metamorphic. Fire, layers and squeezing."

Spike laughed. "You're a real rock detective now."

"Can I keep the pumice?" asked Little Thunder. "I want to float it in my water bowl."