OG Theory by Wegener

evidence for continual drift

• fossil distribution
• geologic units (edges of stuff fit together)

criticism

• OG theory couldn’t explain why stuff moved

Seafloor Spreading

• mid-ocean ridges: submarine mountain ranges
• deep-sea trenches: trenches in the depth
• fracture zones: vertical cracks

Paleomagnitism

Because earth magnetic field changes, measuring sediment polarization helps us figure out where stuff moved.

The magnetic poles, unlike other planets, don’t go anywhere. But every so often they reverse.