Ocean Trenches and Mid-Ocean Ridges

Where is newly formed, less dense oceanic crust found on the ocean floor?

Closest to the mid-ocean ridge

How are ocean trenches created?

Two oceanic plates collide at a convergent boundary. The older, denser oceanic crust subducts into the mantle.

How are mid-ocean ridges formed?

Two oceanic plates move apart at a divergent boundary and the magma rises, cools and hardens

Deep-Ocean Trenches

Underwater canyons

Mid-Ocean Ridges

Underwater mountains

Hydrothermal Vents

Vents along a mid-ocean ridge where super heated water shoots out from

Where is older, denser oceanic crust found on the ocean floor?

Farther away from a mid-ocean ridge

Why doesn't the ocean floor get bigger if the ocean floor is spreading in some areas?

As new rock is added along the mid-ocean ridge, old rock subducts into the trenches

Mariana Trench

Deepest trench in the world

Mid- Ocean Ridges are found...

In all of earth's oceans

Along what feature of the ocean floor does seafloor spreading begin?

Mid-Ocean Ridge

Why is the Pacific Ocean shrinking?

Older oceanic crust is subducting into trenches on the ocean floor fasting than new crust is being produced along the mid-ocean ridge

Chemosynthesis

Process where life along a hydrothermal vent uses chemicals to make food

What two processes work together to move the ocean floor creating new ocean floor along a mid-ocean ridge and destroying ocean floor along a trench?

Seafloor spreading and subduction

What happens to oceanic crust at a deep ocean trench?

The crust sinks (subducts)back into the mantle

Why is the Atlantic Ocean getting bigger?

The ocean floor of the majority of the Atlantic Ocean forms at a divergent boundary along a mid-ocean ridge resulting in sea floor spreading. There are very few trenches in the Atlantic Ocean so older crust has nowhere to go.

Seafloor Spreading

The process of new sea floor being added along a mid-ocean ridge

What happens to the deep cold ocean water as it seeps into cracks along the mid-ocean ridge?

The water becomes super heated and shoots out from the sea floor at high speeds