The Changing Earth

To recognize the evidence for changes in the Earth Learning Objective To recognize the evidence for changes in the Earth Learning Outcomes To be able to recall that rock provide evidence for changes in the Earth (erosion and sedimentation, fossils, folding, radioactive dating and craters)

Success Criteria Good if you can explain how fossils can be used to date rocks. Excellent if you can recall other information which suggests that the Earth is constantly changing. Exceptional if you can explain the evidence for these theories and any limitations they have.

Volcanic eruptions produce Igneous rock.

Sedimentary rock is made from layers of sediment at the Earth’s surface or within bodies of water. Over time the sedimentary layers become compressed and ‘stick’ together.

Sedimentary Rock Movement Faulted Sedimentary Rock Movement Folded Tilted

Immense temperatures and pressures within the Earth change sedimentary or intrusive igneous rock to metamorphic rock.

The natural process of erosion has worn away the rock.

If the Earth were not constantly changing all mountains would be worn down by the force of erosion.

The Grand Canyon Over millions of years the Colorado river has worn down from the surface to create the Grand Canyon. At present the Canyon is 1.83 km deep. The rocks at the bottom were deposited over 1.5 billion years ago.

Grand Canyon Fossils

Surface Canyon Floor

Throughout its history Earth has continually been bombarded by objects from space. This 70km diameter crater is estimated to have been created 200 m years ago.

Radiometric Dating The mineral Zircon is radioactive. It becomes less radioactive over time. If we know the rate of radioactive decay we can estimate how old the rocks are.

Success Criteria Good if you can explain how fossils can be used to date rocks. Excellent if you can recall other information which suggests that the Earth is constantly changing. Exceptional if you can explain the evidence for these theories and any limitations they have.