gen-define-fault-types-and-give-one-short-worked-example-30e2

Define fault types and give one short worked example.

# Fault Types ## **Three Main Types of Faults:** ### 1. **Normal Fault** - Hanging wall moves **DOWN** relative to footwall - Caused by **tensional stress** (pulling apart) - Common at divergent boundaries - Dip angle typically 60° ### 2. **Reverse Fault** - Hanging wall moves **UP** relative to footwall - Caused by **compressional stress** (pushing together) - Common at convergent boundaries - **Thrust fault** = reverse fault with dip < 45° ### 3. **Strike-Slip Fault** - Blocks move **horizontally** past each other - Caused by **shear stress** - Common at transform boundaries - No hanging wall/footwall designation --- ## **Worked Example:** **Problem:** A geologist observes a fault where: - Rock layer A (originally continuous) is now separated - The eastern block has moved upward relative to the western block - The fault plane dips 35° to the east - The eastern block was originally on top of the fault plane **Solution:** 1. **Identify hanging wall & footwall:** - Hanging wall = block above fault plane = **eastern block** - Footwall = block below fault plane = **western block** 2. **Determine movement:** - Hanging wall moved **UP** relative to footwall 3. **Classify fault:** - This is a **REVERSE FAULT** (specifically a **thrust fault** because dip < 45°) - Indicates **compressional stress** in the region