Lecture 13B / Mass Wasting

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Transcript Lecture 13B / Mass Wasting

Mass Wasting
GLG 101 - Physical Geology
Bob Leighty
These notes and web links are your primary “lecture” content in this class.
Additionally, various articles are assigned each week to supplement this “lecture”
information. I believe you’ll have enough information to reference without having
to purchase a costly textbook.
These lecture notes are very similar to the ones I use in my traditional classes.
You’ll find they are loaded with imagery and streamlined text that highlight the
most essential terms and concepts. The notes provide a framework for learning
and, by themselves, are not meant to be a comprehensive source of information.
To take advantage of the global knowledge base known as the Internet, I have
included numerous hyperlinks to external web sites (like the Wikipedia, USGS,
NASA, etc.). Follow the links and scan them for relevant info. The information
from linked web sites is meant to supplement and reinforce the lecture notes –
you won’t be responsible for knowing everything contained in them.
As a distance learning student, you need to explore and understand the content
more independently than in a traditional class. As always, I will help guide you
through this learning adventure. Remember, email Dr. Bob if you have any
questions about today’s lecture ([email protected]).
Leave no questions behind!
Explore and have fun!
Mass
Wasting
Mass Wasting
Why Do We Care?
Before
After
This South American town was buried by a rock avalanche
Mass
Wasting
What is Mass Wasting?
 Downslope movement of rock & soil under the influence of gravity
 Classify on the basis of:
1) material (rock, mud, soil)
2) type of motion (fall, slide, flow)
3) rate (fast, slow)
Mass
Wasting
What is Mass Wasting?
 Mass wasting & stream erosion sculpt Earth’s surface
Mass
Wasting
Types of Mass Wasting
Rockfall
 Freefall of pieces of bedrock
Mass
Wasting
Types of Mass Wasting
Rockfall
 Talus (scree) – Rockfall debris
Mass
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Types of Mass Wasting
Rockfall
Mass
Wasting
Types of Mass Wasting
Rockslide
 Rapid sliding of bedrock downslope over an inclined weak layer
Mass
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Types of Mass Wasting
Rockslide
 Caused by weak layers in:
> Sedimentary rocks (bedding)
> Metamorphic rocks (foliation)
> Fractured rocks (joints)
Mass
Wasting
Types of Mass Wasting
Rockslide
Gros Venture, WY (1925)
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Types of Mass Wasting
Rock Avalanche
 Very rapid downslope movement of “dry” bedrock
Before
After
Mass
Wasting
Types of Mass Wasting
Rock Avalanche
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Wasting
Types of Mass Wasting
Mudflow
 Rapid flow of water-saturated mud & rock
Mass
Wasting
Types of Mass Wasting
Earthflow
 Slow-rapid collapse of oversteepened slopes
Mass
Wasting
Types of Mass Wasting
Earthflow
Mass
Wasting
Types of Mass Wasting
Earthflow
Mass
Wasting
Types of Mass Wasting
Earthflow
Mass
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Types of Mass Wasting
Earthflow
Mass
Wasting
Types of Mass Wasting
Creep
 Soil/bedrock slowly moves (creeps) downhill
Mass
Wasting
Types of Mass Wasting
Creep
Mass
Wasting
WWW Links in this Lecture
> Mass wasting - http://en.wikipedia.org/wiki/Mass_wasting
> Rockfall - http://en.wikipedia.org/wiki/Rockfall
> Scree - http://en.wikipedia.org/wiki/Scree
> Mudflow - http://en.wikipedia.org/wiki/Mudflow
> Earthflow - http://en.wikipedia.org/wiki/Landslide#Earth_flow
> Creep - http://en.wikipedia.org/wiki/Downhill_creep