Title: 8.1 Types of Mass Movements Page #: 68 Date: 2/4/2013 Table of Contents Title: 8.1 Types of Mass Movements Page #: 68 Date: 2/4/2013

Objective Students will be able to distinguish between types of mass movements.

Word of the Day Mass Movement: The downslope movement of soil and weathered rock resulting from the force of gravity.

Types of Mass Movements There are 4 types of mass movements: Creep Flows Slides Rockfalls

Types of Mass Movements Creep: Slow, steady, downhill flow of loose weathered Earth materials - especially soil. Occurs over long periods of time. Causes vertical structures to tilt. Solifluction: When subsurface permafrost melts, turns to mud and allows surface layer of soil to move downward.

Creep: Results in titled structures.

Types of Mass Movements Flows: When Earth materials move as if they were a liquid. Flows can be really slow, or really fast. Earth flows: Soil - moves a few centimeters a year. Mudflows: Mud and water - can move 100 km / hour. Common after earthquakes and volcanoes.

Flows: Earth materials move a as liquid

Types of Mass Movements Mudflows: Lahar - a mudflow that occurs after a volcanic eruption. Happens on volcanoes that are topped with snow. Mudflows are also common in semiarid regions after heavy rains because there is no vegetation to prevent materials from moving.

Lahars occur on volcanoes that are topped with snow.

Types of Mass Movements Slides: Landslides - Rapid downslope movement of Earth. Happens when a thick block of soil, rock and debris separates from bedrock. Material moves as one block. In U.S. landslides kill 25 - 50 people per year and cause almost 2 billion dollars in damage. Rockslide: A sheet of rock moves downhill on sliding surface.

During a landslide materials move as 1 block

Landslides cause severe damage.