The Tectonic Plates theory
Plate tectonics is the idea that Earth’s outer shell is broken into large pieces called plates. These tectonic plates move slowly over time, shaping mountains, oceans, and continents. The theory is based on Earth’s structure: a hard outer layer called the lithosphere floats on a softer layer called the asthenosphere. German scientist Alfred Wegener first suggested that continents move, calling it continental drift, but the full theory of plate tectonics came later.
- When plates push together (convergent boundaries), they form mountains or volcanoes like the European Alps or the Himalayas.
- When they move apart (divergent boundaries), they create new ocean floor like the Mid-Atlantic Ridge.
- When they slide past each other (transform boundaries), they cause earthquakes, like at the San Andreas Fault.
The Tectonics Plates theory explained
This video explains the basics of plate tectonics. It shows how Earth’s surface is made of moving plates and how those plates helped break up the supercontinent Pangaea. It also describes the three main ways plates move: toward each other (convergent – makes mountains and volcanoes), away from each other (divergent – makes mid-ocean ridges), and past each other (transform – causes earthquakes).
The world before the Plate Tectonics
Pangaea was a supercontinent that existed about 335 to 175 million years ago. Back then, nearly all of Earth’s land was joined in one big piece. But the Earth’s outer layer is broken into large moving plates. This movement, called plate tectonics, slowly caused Pangaea to break apart into smaller landmasses. These landmasses kept moving and became the continents we know today. Plate tectonics explains how and why Pangaea split and how Earth’s surface keeps changing.