Fossils and what they tell us about the past
Chemistry · Key Stage 2 · The School
A fossil is a message from the past
A fossil does more than show what an animal looked like. It shows WHERE that animal lived and WHAT the land was like at the time. Finding the right fossil in the right rock layer tells scientists what a place was like millions of years ago.
The highest rocks above sea level are on Mount Everest. Geologists, who study rocks, have found tiny broken pieces of crinoids in the grey limestone near its top. Crinoids are sea animals, and some are called sea lilies. Step 1: crinoids lived in the sea, so this rock formed in the sea. Step 2: limestone often forms from shells and corals that pile up on a sea floor. Step 3: geologists read this limestone as made in a warm, shallow sea. Step 4: the summit now stands 8,849 metres above sea level. That is close to 9,000 metres, or 9 kilometres. The rock began close to sea level, so it has risen roughly 9 kilometres. Geologists date this limestone to about 450 million years ago. Answer: back then this rock lay on a warm sea floor. Huge forces, as India pushed into Asia, have since lifted it. The fossil is no mistake. It is the mountain that is new.
Reading the story in the rock
A layer full of shell fossils suggests that spot was once underwater. A layer full of fern fossils suggests it was once a warm, damp forest. Reading fossils layer by layer is like reading pages in a very old book about the same patch of ground.
Fossils and changing climate
Fossils of plants that only grow in warm places have been found in rock from parts of the world that are cold today. That tells scientists the climate there has changed a great deal over a very long time — evidence written in stone, long before anyone could measure temperature directly. A single fossil, correctly read, can carry a huge amount of information.