Deep Time and Plate Tectonics
Core facts about Earth's age, radiometric dating, and the moving lithospheric plates.
Keyboard Shortcuts
💡 Pro tip: Use keyboard shortcuts for faster studying!
Study Smart Tips for Deep Time and Plate Tectonics
Master these concepts using proven study techniques that actually work:
Active Recall
Test yourself before flipping each card to strengthen memory retention
Spaced Repetition
Review difficult cards more frequently than easy ones
Multiple Sessions
Break study time into shorter, focused sessions
Explain Aloud
Verbalize answers to reinforce understanding
Questions Covered in This Set
10 cards to master
How old is the Earth?
About 4.54 billion years, dated mainly by radiometric methods.
In the 'Earth history as one calendar year' model, when does Homo sapiens appear?
December 31 at 23:36 — all of recorded history fits in the last ~2 seconds.
When was the Cambrian explosion on the calendar model, and how long ago in real time?
November 19; about 539 million years ago, when complex animals with hard parts appeared.
Why is carbon-14 useless for geology?
Its half-life is only 5,730 years, so it works out to roughly 50,000 years — an archaeology tool, not a geology tool.
Why are zircon crystals ideal for uranium-lead dating?
They incorporate uranium when they crystallise but reject lead, so any lead inside must come from decay. The oldest (Jack Hills, Australia) are 4.4 billion years old.
What is the radiometric age equation?
t = (t½ / ln2) · ln(1 + D/P), where D = daughter atoms and P = surviving parent atoms.
Lithosphere vs. asthenosphere
Lithosphere: the rigid outer ~100 km (crust + top of mantle), broken into ~15 major plates. Asthenosphere: hotter, ductile solid rock beneath that flows like stiff putty over million-year timescales.
What is the dominant driving force of plate motion?
Slab pull — a cold, dense oceanic plate sinking at a subduction zone drags the rest of the plate with it; ridge push and mantle convection also contribute.
How far does a plate moving 3 cm/yr travel in 100 million years?
About 3,000 km — roughly the width of the Atlantic Ocean. Rate × deep time = continents.
What happens at a divergent boundary?
Plates separate, magma rises, and new oceanic crust forms — e.g. the Mid-Atlantic Ridge.
