Lecture Notes: Plate Margins for GCSE Geography

Introduction

• Focus: Understanding three different plate margins required for the GCSE Geography exam.
• Plate margins covered: Destructive, Constructive, and Conservative.

Destructive Plate Margin

• Definition: Occurs when two plates move towards each other.
• Types of Plates Involved:
  • Oceanic Plate: Carries an ocean, denser.
  • Continental Plate: Carries land.
• Process:
  • The denser oceanic plate is forced under the continental plate (subduction).
  • This area is the subduction zone.
  • Friction between the plates causes heat, melting the rock into magma.
  • Magma under pressure rises up, causing volcanic eruptions.

Constructive Plate Margin

• Example: Mid-Atlantic Ridge.
• Description:
  • Two oceanic plates move in opposite directions.
  • A gap forms, creating a weakness in the Earth’s crust.
  • Magma exploits the gap, forming underwater volcanoes.
  • Magma cools and solidifies, creating underwater mountain ranges.

Conservative Plate Margin

• Description:
  • Plates may move in the same direction at different speeds or in opposite directions.
  • Can become stuck, allowing pressure to build up.
  • Sudden release of pressure causes earthquakes.

Key Points for Exams

• Understand and memorize the characteristics of each plate margin.
• Be able to draw diagrams illustrating each type of plate margin.

Additional Advice

• Revise thoroughly with focus on process description for each margin.
• Diagrams may be required in exams to support answers.