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Earthquakes are caused by the sudden release of energy when tectonic plates move along faults. Most earthquakes occur at plate boundaries where plates collide, slide past each other, or pull apart. The sudden movement releases enormous amounts of energy in the form of seismic waves, causing the ground to shake.

Geologists use two main approaches: relative dating (determining if one rock is older than another) and absolute dating (determining the actual age in years). Relative dating uses principles like superposition (younger layers are on top) and fossil correlation. Absolute dating relies on radioactive decay of elements like uranium and potassium, which decay at known rates.

A mineral is a naturally occurring, inorganic solid with a definite chemical composition and ordered crystal structure. A rock is an aggregate of mineral grains bound together. For example, quartz is a mineral, while granite (made of quartz, feldspar, and mica) is a rock.

Earth's lithosphere is divided into several rigid plates that move across the asthenosphere. Convection currents in the mantle drive these movements. Plates interact at boundaries in three ways: divergent (moving apart), convergent (colliding), and transform (sliding past each other). These interactions create earthquakes, volcanoes, and mountains.

The rock cycle describes how rocks transform over time. Magma cools to form igneous rock. Igneous rock is weathered and eroded into sediment, which is compacted into sedimentary rock. Any rock can be buried and subjected to heat and pressure, transforming it into metamorphic rock. Metamorphic or any other rock can eventually be melted back into magma, completing the cycle.

Volcanoes form where hot molten rock (magma) from Earth's interior can reach the surface. Most occur at plate boundaries, particularly at subduction zones (where plates collide) and mid-ocean ridges (where plates separate). Some form over hotspots where mantle plumes rise through the lithosphere. Magma is less dense than surrounding rock, so it rises and erupts.

Fossils form when organisms are buried in sediment after death. The sediment compacts and hardens into rock, preserving the organism's remains or traces. Permineralization (filling of pores with minerals), replacement (original material replaced by minerals), and molds and casts are common fossilization processes. Fossilization requires rapid burial in appropriate environments like seas, lakes, or volcanic ash.

Metamorphic rocks form when existing rocks are transformed by heat, pressure, or chemical activity, usually deep in the Earth during mountain building. Unlike melting, the rock remains solid. Heat causes minerals to rearrange and new minerals to form. Common metamorphic rocks include marble (from limestone), slate (from shale), and schist (from various rocks).