Divergent Plate Tectonics: Boundaries that Pull Apart
Earth has 7 major plate tectonic boundaries and 10 or so minor ones. There are 3 plate tectonic types that interact with each other in 3 ways:
- Divergent plate boundaries pull apart from each other
- Convergent plates push into each other
- And conservative or transform plate boundaries slide across from each other
This divergent plate boundaries map displays where plates pull apart from each other. If you scroll down the page, you’ll notice how this map is similar to the map showing the youngest rock. To pique your curiosity, these underwater volcanoes spew out lava.
And it turns out, these mid-oceanic ridges (rift valleys) has the youngest geologic rocks on the planet. Generally, ocean floor consists of mostly igneous rocks “basalt” which spread at these mid-oceanic ridges.
Plates move apart at divergent boundaries
Beneath the oceans, lava erupts every day. Because it’s all are underground, we don’t realize it’s even happening.
Actually, the Earth has 70,000 km of continuous volcanoes under the ocean. More specifically, the volcanoes are at mid-oceanic ridges. If you took all the water away from the oceans, it would be the most prominent feature on Earth.
Plate tectonics begin at mid-oceanic ridges where plates are moving apart. Because plates pull apart from each other at divergent plates, lava spews out to create the youngest geological rocks on Earth.
The African Plate is in the process of rifting apart into two separate plates where it will become ocean. In addition, the Somalian and Nubian plates will one day tear apart and become new ocean.
So divergent plates pull apart from each other at mid-oceanic ridges, which creates some of the youngest geological rock and even new oceans. But what happens at the opposite end of the plate?
The youngest rock form at divergent plate boundaries
Hidden beneath Earth’s oceans, underwater volcanoes spew out lava at mid-oceanic ridges (rift valleys).
Because divergent plates move apart from each other at these mid-oceanic ridges, magma flows upwards from the mantle beneath.
When the lava hardens, it becomes dark igneous rock or “basalt” at rift volcanoes.
Because divergent plates fill in the gaps with basalt, oceanic crust turns out to be very young geologically.
Over time, the plates grow at oceanic crust and older rock is pushed away from mid-oceanic ridges.
