Seafloor Spreading & Continental Drift

[!] STUDY GUIDE: Big Ideas Use to answer form questions

1.Plates rest on the asthenosphere (plastic solid, not liquid); convection drives movement. Students often think plates float on liquid magma like boats on water, but evidence from investigations shows otherwise. Use data from today's stations to identify which observations best support this understanding.

2.Plates move 1-10 cm/year (fingernail growth rate); changes visible over millions of years. Students often think continents move fast enough to notice, but evidence from investigations shows otherwise. Use data from today's stations to identify which observations best support this understanding.

3.Earthquakes cluster at plate boundaries where stress accumulates. Students often think earthquakes happen randomly across Earth, but evidence from investigations shows otherwise. Use data from today's stations to identify which observations best support this understanding.

DRAW KEY TERMS Google each → Images tab → sketch what you see

OTHER VOCAB: spreading rate · symmetry · evidence · Pangaea · continental drift · subduction · fossil distribution

Magnetic Reversal

When Earth's magnetic poles switch direction

Seafloor Spreading

Process of creating new oceanic crust at mid-ocean ridges

Mid-Ocean Ridge

Underwater mountain chain where new seafloor forms

Polarity

The direction of a magnetic field (normal or reversed)

WRITE FOCUS QUESTION Your initial thinking

The Mid-Atlantic Ridge is a 10,000-mile underwater mountain range — taller than most peaks on land. Scientists found that the youngest rocks are at the center of the ridge, and the oldest are near the continent edges. Even stranger, magnetic patterns in the rock form perfect mirror images on both sides.

What process creates new ocean floor at mid-ocean ridges, and what evidence proves it?

I think...

WRITE AFTER HOOK FORM Reflect before continuing

I learned that...

Station 1 — Seafloor Spreading Evidence

I observed that...

This shows that...

The key concept is...

Station 2 — Pangaea Puzzle Investigation

The data shows...

This connects to...

The main idea is...

This connects to what we learned because...

I can apply this by...

DRAW CONCEPT MODEL Show your understanding visually

Draw a model that shows the main concept. Include labels and arrows to explain relationships.

Labels included

Relationships shown

Key terms used

CHECK TEST YOUR THINKING Rate each: FALSE ← 1–2–3–4–5 → TRUE

1. Continents move fast enough to notice or measure without special equipment.

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2. Tectonic plates float on top of a giant layer of fast-moving liquid magma.

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3. Earthquakes and volcanoes occur randomly all over Earth's surface instead of following specific patterns.

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4. Ocean currents or earthquakes push tectonic plates apart at mid-ocean ridges.

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5. Matching magnetic stripe patterns on both sides of a mid-ocean ridge show that new rock forms and spreads outward symmetrically.

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Pick any TWO statements — especially any you rated 2, 3, or 4. Justify your rating with evidence:

Statement #___ — I rated it ___ because:

THINK SCIENTIST CIRCLE DEBRIEF Reflect after class discussion

AHA! Moment

The one I changed my thinking most about is...

Remaining Question

I still wonder...

WRITE FOCUS QUESTION REVISIT Final written response

What process creates new ocean floor at mid-ocean ridges, and what evidence proves it?

Word Bank: magnetic reversal · polarity · spreading rate · mid-ocean ridge · seafloor spreading · symmetry · evidence · continental drift · Pangaea · subduction · fossil distribution