Inside the Earth
Map
Arrows point from what you learn first to what it opens. Point at a concept to light up its chain and where it comes back deeper. Right-click a concept (or press and hold it) for its lessons and stories.
- Proven to depth123
- Open
- Locked
- Comes back deeper
Learning path
In the order the concepts build on each other.
- Seismic wavesLockedWhen rock deep in the Earth suddenly breaks, the energy it releases spreads out in every direction as seismic waves, like ripples on water. The place where the rock broke is the focus of the earthquake. Seismographs record the waves as a zigzag line. The waves travel faster through hard, dense rock than through soft material, and some cannot pass through liquid at all, which is how scientists have learned what lies deep inside the Earth without digging.Opens after: Energy
- Layers of the EarthLockedThe Earth is built in layers. By what they are made of, there are three: the thin crust we live on, the thick, hot, rocky mantle beneath it, and the core at the centre, mostly iron and nickel, about 6,400 km down. By whether they are solid, soft or molten there are five: the rigid lithosphere (the crust and the top of the mantle, about 100 km), the soft asthenosphere it rests on, the solid lower mantle, the liquid outer core and the solid inner core, kept solid by enormous pressure. The lithosphere is broken into pieces that move slowly over the asthenosphere.Opens after: Seismic waves
- EarthquakesLockedThe lithosphere is broken into great plates that move a few centimetres a year. Where plates push, pull apart or slide past each other, the brittle rock at their edges bends and stores energy until it suddenly breaks and shifts: an earthquake. The breaks, called faults, stay weak, so earthquakes happen again and again along them, and the shaking and damage are worst near them. Iran sits where the Arabian plate pushes into the Eurasian plate, so it has many faults and earthquakes. Most earthquakes are too small to feel.Opens after: Layers of the Earth
- VolcanoesLockedDeep down, rock sometimes melts into magma. Being lighter than the solid rock around it, magma rises and gathers in a magma chamber; when the pressure of its gases is high enough it erupts up the vent and out of the crater, building a cone of cooled lava and ash. On the surface it is called lava. A volcano gives out solids (rock and ash), liquid (lava) and gases, mostly steam and carbon dioxide. Volcanoes are dangerous, but they also give fertile soil, light rocks like pumice, hot springs and new islands. A volcano may be active, dormant or extinct; Damavand, Iran's highest mountain, is a volcano that still lets out gas.Opens after: Layers of the Earth
- Earthquake safetyLockedBeing ready saves lives. Before an earthquake: strong or strengthened buildings, tall furniture fixed to the walls, heavy things kept low, an emergency bag, a family plan and drills. During the shaking: drop, cover under a sturdy table and hold on, away from windows and tall shelves; never run for the stairs or use a lift; outdoors, move away from buildings, poles and wires. After: stay calm, check for injuries, leave carefully because aftershocks may come, report a smell of gas without switching anything on, listen to official messages and help those who need it.Opens after: Earthquakes
Connections to other domains
- Layers of the Earth, depth 2 needs States of matterMatter and Its Properties
- Seismic waves needs EnergyEnergy