B2
Lesson Summary
Vocabulary Link
- seafloor spreading
- magnetic reversal
- Curie temperature
- paleomagnetism
- normal polarity
- reversed polarity
- The world’s oceans contain mid-oceanic ridges, continuous mountain ranges that completely surround the globe.
- Deep ocean trenches are often found at the edges of continents or along island chains around the Pacific Ocean.
- The theory of seafloor spreading states that new crust is constantly being formed by solidifying magma at mid-oceanic ridges; this new crust, over time, slowly moves away from the mid-oceanic ridge that formed it.
- Magnetic materials retain a record of the Earth’s magnetic poles when their temperature falls below a point known as the Curie temperature.
- Paleomagnetism is the study of the Earth’s magnetic properties over time.
- Magnetic striping, symmetric magnetic bands of normal and then reversed polarity, is the result of a series of magnetic reversals of the Earth’s north and south magnetic poles.
- Studies from seafloor drilling reveal that the age of ocean sediment increases the farther away it is from a mid-oceanic ridge.