Part 4: Divergent Boundaries & Rifting
Where Plates Pull Apart
Divergent boundaries are constructive margins where new lithosphere is created. Mid-ocean ridges form the longest mountain chain on Earth, while continental rifts mark the early stages of ocean basin formation. Understanding the rift-to-drift transition reveals how continents break apart and new oceans are born.
~60,000 km
Global Ridge Length
1–18 cm/yr
Spreading Rates
~7 km
New Oceanic Crust Thickness
Topics in This Part
4.1 Mid-Ocean Ridges
Ridge morphology, fast vs slow spreading, and axial valley structure
4.2 Continental Rifting
Pure shear vs simple shear models, the East African Rift system
4.3 Oceanic Crust Formation
Magma chambers, sheeted dikes, and the ophiolite sequence
4.4 Rift-to-Drift Transition
Breakup unconformity, passive margin evolution, and sedimentary basins