Mysterious tunnels in desert rocks may be the work of unknown microbes, hinting at a hidden world inside marble and limestone ...

Together with the pressure from plate movement, this heat recrystallized the limestone into whitish-gray marble and created ripples of brown and yellow rock where impurities were trapped in the ...

CONNOR: Good thinking! I read a bit about limestone on the bus journey. Limestone is a sedimentary rock created by layers of skeletons and shells of sea creatures found in ancient, warm ...