Lesson Library
Every facet of earth science
Study chapters in order — each builds on the previous
1
Earth's Interior
Crust, mantle, outer core, inner core — and the geophysical methods that revealed them.
1
Earth's Internal Structure
From crust to inner core — the four-layer structure of Earth and the seismic evidence that revealed it.
12 min 150
2
The Crust — Continental vs. Oceanic
The ocean floor and the land beneath your feet are made of completely different rock — and that difference explains almost everything about Earth's surface.
13 min 150
3
The Mantle and Its Convection
The mantle is solid rock — yet it flows. Understanding how and why unlocks the engine behind earthquakes, volcanoes, and the entire plate-tectonic system.
13 min 150
4
Earth's Core and Magnetic Field
Deep in Earth's liquid iron core, a self-sustaining dynamo generates the magnetic field that shields life from the Sun's relentless particle stream.
13 min 150
2
Minerals & Crystals
The five criteria that define a mineral, identification techniques, and how crystals grow.
1
What Defines a Mineral
Five criteria separate a true mineral from coal, glass, pearl, and thousands of other solids — and the distinction unlocks everything about how rocks are built.
13 min 150
2
Identifying Minerals — Hardness, Streak, and Cleavage
A fingernail, a penny, and a porcelain tile are all a geologist needs to identify most minerals — because crystalline structure guarantees that every sample of the same mineral behaves identically.
13 min 150
3
The Rock-Forming Minerals
~5,500 mineral species exist, but fewer than 30 build virtually all of Earth's rocks. Learn the short list — and what each mineral tells you about the rock it came from.
14 min 150
4
Crystal Systems — Introduction
Every snowflake has six sides for the same reason every halite grain is a cube — the external shape of a crystal is the public face of its internal atomic geometry.
13 min 150
3
The Rock Families
Igneous, sedimentary, and metamorphic rocks — how they form and how to read them.
1
The Rock Cycle Overview
Every rock has a biography. The rock cycle is the framework for reading it — a continuous system of transformation that has been running since Earth formed.
13 min 150
2
Igneous Rocks
Obsidian and granite can share the same chemistry yet look nothing alike. The difference is cooling rate — the master variable that controls every igneous rock's texture.
13 min 150
3
Sedimentary Rocks
The Grand Canyon's layered walls are 1.8 billion years of Earth history written in sediment. Each layer is a snapshot — an ancient sea, desert, or river frozen in stone.
13 min 150
4
Metamorphic Rocks
Michelangelo's David began as a seashell. Marble is metamorphosed limestone — recrystallised by heat and pressure into something entirely new, without ever melting.
13 min 150
4
Plate Tectonics
The theory that unified geology — moving plates, divergent and convergent boundaries, and hotspots.
1
The Theory of Plate Tectonics
In 1912, Wegener said the continents move. Geologists laughed. Fifty years later, seafloor spreading proved him right — and gave Earth science its unifying theory.
13 min 150
2
Plate Boundaries
The San Andreas has earthquakes but no volcanoes. Iceland tears apart and erupts constantly. The Himalayas rise with no volcanic chain. Three boundaries — three completely different outcomes.
13 min 150
3
Subduction and Orogenesis
The Andes were built by an ocean floor that no longer exists. Subduction is the engine — recycling oceanic crust, generating arc volcanoes, and raising mountain ranges 7,000 metres above sea level.
13 min 150
4
Hotspots and Mantle Plumes
Kīlauea sits 3,200 km (1988 mi) from the nearest plate boundary. The Hawaiian Islands grow older to the northwest like a timestamp trail — each island the frozen record of a plate moving over a fixed heat source in the mantle.
13 min 150
5
Surface Processes
Weathering, erosion, rivers, glaciers, and coastlines — how landscapes are sculpted over time.
1
Volcanic Landforms
A volcano's silhouette is its autobiography. The gentle dome of Mauna Loa, the steep cone of Fuji, the sunken depression of Yellowstone — each shape is the accumulated record of magma composition and eruption history.
13 min 150
2
Weathering and Erosion Landforms
Arches National Park's 2,000+ stone arches weren't carved by rivers or hands — ice expanded in cracks and acid dissolved cement. Weathering is the invisible sculptor of every landscape.
13 min 150
3
River Systems and Landscapes
The Colorado River carved the Grand Canyon — 1.6 km (1.0 mi) deep, 446 km (277 mi) long — through 1.8 billion years of rock. Rivers are Earth's most powerful surface sculptors, and every fluvial landform is a chapter in a river's story.
13 min 150
4
Glacial and Coastal Landforms
20,000 years ago, ice sheets covered 30% of Earth's land and sea level was 120 m (394 ft) lower. Today, waves attack every coastline 24 hours a day. Ice and ocean are Earth's final two great sculptors — and their work is written across every high-latitude landscape and every continental margin.
13 min 150
6
Path Assessment
Test your knowledge across all five chapters of Earth Foundations.