Earth science
Study the layers beneath your feet, moving plates, rocks, eruptions and circulating water through cutaway models and worked questions.
- 1Rocks and mineralsHow does a grain of quartz end up in granite, then in sand on a beach, then in sandstone and finally in quartzite? Click through the rock cycle, learn to tell igneous, sedimentary and metamorphic rocks apart, test minerals on the Mohs scale and see how geologists date rocks 4 billion years old.6 Units
- 2Plate tectonicsThe ground under your feet rides on a plate that moves a few centimetres a year. Start with the inside of the Earth and the earthquake waves that revealed it, then follow plates apart at ridges, together at trenches and past each other on faults, and end with the clues that once joined the continents into Pangaea.8 Units
- 3Volcanoes and earthquakesLava can reach about 1,200 °C, and one step on the magnitude scale means about 32 times more energy. This course follows molten rock from the mantle to the surface, sorts volcanoes by shape and eruptions by size, visits the Hawaiian hotspot, explains how earthquakes are measured and ends with general safety information.6 Units
- 4The water cycleA water molecule that evaporates from the sea stays in the air for about nine days before it falls again. Follow water through the cycle in a 3D block of land: sea, river, mountain and the aquifer under your feet. Change the temperature and watch evaporation and the snow line respond.6 Units
A planet read from layers and traces
Earth science asks how processes that are difficult to see leave evidence we can examine. Seismic waves help explain the inside of the planet; rocks record cooling, burial and alteration; water moves between places above and below the ground. The courses connect these observations without treating Earth as a collection of disconnected names. Read a diagram for what it represents, then ask what observation supports it. A model of a plate boundary and a specimen of rock answer different questions about the same changing planet.
Build the structure before studying eruptions
Begin with Plate tectonics. Its units move from Earth’s layers and seismic evidence to plates and their speeds. Divergent, convergent and transform boundaries explain different kinds of motion. The Ring of Fire and the evidence for Pangaea bring those mechanisms into a larger geographical and historical picture. Keep the boundary types distinct rather than learning a single picture of plates colliding.
Read Rocks and minerals alongside it. Minerals come first, followed by igneous, sedimentary and metamorphic rocks, the rock cycle and rock ages. Use the formation process to explain a category, not just the appearance of a sample. The cycle connects processes that would otherwise look like separate vocabulary lists.
Continue with Volcanoes and earthquakes. It distinguishes magma from lava, compares volcano types and introduces eruptions and the Volcanic Explosivity Index. Hotspots and Hawaii sit beside the plate-boundary account rather than disappearing into it. Earthquakes and magnitude lead into a unit on staying safe.
The water cycle follows water through storage, evaporation and transpiration, condensation, precipitation, runoff and groundwater. It connects what happens in the air with rivers and the ground, rather than ending the explanation when rain reaches the surface.
Turn a cutaway into an explanation
Rotate the Earth model and inspect the layers, then turn on seismic waves to follow their paths. Switch among boundary models and describe which way the plates move before naming the boundary. The rock lab lets you follow cooling, lithification and metamorphism. In the water model, change temperature, watch precipitation and inspect the cut front face for groundwater. Explain each change using the process named in the unit, not merely the colour or movement of the animation.
Keep evidence and illustration separate
The mid-ocean ridge model is explicitly not to scale. Treat it as a guide to a process, not a measurement of the landscape. Compare the account of plate boundaries with the separate hotspot unit before claiming that every volcano has the same setting. Revisit the seismic evidence when describing internal layers, and the rock-age unit when discussing time. The unit questions and summaries provide places to check these distinctions before moving to another process.
Questions about this subject
What is the difference between a rock and a mineral?
A mineral has a characteristic composition and an orderly internal structure, while a rock is an aggregate of one or more minerals. Granite can contain feldspar, quartz and biotite mica as separate interlocking grains. The same minerals may also occur in sandstone, but their arrangement records a different history of formation from that of granite. Rocks and minerals
Why does granite have visible crystals?
Magma trapped underground cools slowly, giving atoms time to join growing mineral crystals. Those crystals can become large enough to see without magnification, producing the coarse texture of granite. Rocks that cool rapidly at or near the surface instead have crystals too small to see easily, or can be glassy, so texture helps identify the cooling history. Rocks and minerals
Does metamorphic rock form by melting another rock?
Metamorphism changes rock while it remains solid, through heat, pressure, mineral-rich fluids or a combination of them. Its minerals can recrystallize or rearrange without becoming a melt. If the rock melts completely, it becomes magma and can later solidify as igneous rock, so melting is not simply another name for metamorphism. Rocks and minerals
Why are fossils mostly found in sedimentary rocks?
Sediment can bury organisms quickly, especially those living in or near water, and preserve evidence of them. Igneous rocks form under conditions too hot for that record, while metamorphic heat and pressure generally destroy it. The fossil record therefore favours sedimentary rocks and contains a strong representation of marine life rather than an even sample of all past organisms. Rocks and minerals
Must rocks follow the rock cycle in one fixed order?
No: the cycle includes shortcuts and different routes between rock types. Granite can become gneiss through metamorphism without first turning into sediment, while sandstone can weather back into sand. Any rock heated sufficiently can melt, so the rock cycle describes connected processes rather than a compulsory sequence that every sample must complete in the same direction. Rocks and minerals