Chapter 14. Earth Science

Earth’s structure: crust, mantle, outer core (liquid) and inner core (solid). The crust and uppermost mantle form tectonic plates that slowly move [12].

Plate tectonics explains earthquakes, volcanoes, mountain building and ocean trenches, especially at plate boundaries.

Rocks and the rock cycle

Igneous: formed from cooled magma or lava.

Sedimentary: formed from compacted and cemented sediments, often holding fossils.

Metamorphic: formed when heat and pressure change existing rock.

Weathering and erosion break down and move rock and soil. Rivers, wind, glaciers and waves reshape the landscape.

The water cycle: evaporation, condensation, precipitation and runoff or infiltration.

Atmosphere and weather. Weather results from differences in temperature, pressure and moisture. Climate describes long-term averages. Clouds form when moist air cools and water vapour condenses [12].

Oceans. Cover about 71% of Earth’s surface; currents move heat around the planet.

Dating Earth. Radiometric dating of rocks indicates Earth is about 4.54 billion years old [12].

Review: Which type of rock commonly contains fossils? (Answer: sedimentary rock.)