1. Warm-Up January 21 Write What You Know!
Write everything you know about the prompt below for five minutes, try for at least 3-4 complete sentences.
On the ocean floors, where do you find older oceanic crust, and where do you find newer oceanic crust?

2. Sea-Floor Spreading Notes
(Chapter 1.4)

3. Sea-Floor Spreading Mid-Ocean Ridge:
A landform found at oceanic divergent boundaries
An underwater chain of mountains
A place deep on the ocean floor that flourishes with bizarre life

5. Sea-Floor Spreading Sea-Floor Spreading:
The sea-floor spreads apart along a mid-ocean ridge as new crust is added
Ocean floors move like conveyor belts, pushing the continents along with them

6. Sea-Floor Spreading Evidence from Molten Material
Scientists have visited the mid-ocean ridge and observed rocks that form when lava cools rapidly underwater
Evidence from Drilling Samples
Drill samples show that rocks furthest away from mid-ocean ridge are older (rocks along the coasts), and rocks along the mid-ocean ridge are younger

7. Sea-Floor Spreading Evidence from Magnetic Stripes
Earth’s magnetic poles switch over millions of years
Ocean floor rocks contain iron, which orients to the “North” pole when cooling from lava, forming magnetic stripes along the ocean floor

8. Sea-Floor Spreading Deep-Ocean Trenches Subduction
A landform that occurs at ocean-continent convergent boundaries
A deep underwater trench that forms when the oceanic crust is subducted back into the mantle underneath the continental crust
Subduction
When oceanic crust sinks, melts, and is recycled back into the mantle