Lecture 19- Mass Wasting

Question 1

What is mass wasting?

Answer 1

Failure and downslope movement of rock or unconsolidated materials due to gravity

Question 2

What are unconsolidated materials

Answer 2

Material derived from disintegration and erosion of rocks on the land’s surface, including clay, silt, sand and gravel

Question 3

Is Mass wasting same as landslide

Answer 3

Yes, specific type of mass wasting characterized by a rapid slope failure

Question 4

What is erosion

Answer 4

Geological process in which materials are worn away and potentially transported naturally by wind or water

Question 5

Erosion is driven by?

Answer 5

Gravity

Question 6

Erosion of hills/mountains results in?

Answer 6

Sloped surfaces of varying stability

Question 7

A sloped surface’s stability will depend on:

Answer 7

Angle of the slope
Strength of underlying materials due

Question 8

To determine whether or not a rock will move down a surface, you must consider interaction between rock and sloped surface. IF rock has already broken from the surface, the interaction is ___? Versus if rock is still part of surface, interaction is __? STRENGTH of this interaction is referred to as ___?

Answer 8

Weak
Strong
SHEAR STRENGTH

Question 10

Force of gravity pulls everything towards?

Answer 10

Earth’s centre (straight down)

Question 11

Shear force causes rock to move?

Answer 11

Downhill

Question 12

The steeper the slope, the greater the:

Answer 12

Shear force

Question 13

Shear force: force component parallel to slope
Normal force: force component perpendicular to slope.
Steeper the slope, the greater the

Answer 13

SHEAR FORCE

Question 14

What is shear strength?

Answer 14

Fixed at a specific value, shear strength is the strength of interaction between rock and surface
(Kinda like friction)

Question 15

As slope gets steeper, shear force increases, so

Answer 15

shear force > shear strength

Question 16

Younger mountains tend to be steeper because?

Answer 16

They have not eroded as much as older mountain chains

Question 17

Older mountains are less steep because?

Answer 17

They have experienced hundreds of millions of years of erosion. They can still experience mass wasting thought

Question 18

As rock strength increases, so does?

Answer 18

SHEAR STRENGTH.
(It is the strength of interaction between rock and surface)

Question 19

Rocks made of crystallized molten materials are very strong. They include:

Answer 19

Granite
Basalt
Gneiss

Question 20

What is a crystal:

Answer 20

solid whose atoms are arranged in a
“highly ordered” repeating pattern/solid with a “highly
ordered” microscopic arrangement of atoms.

Question 21

What are potentially strong sedimentary rocks?

Answer 21

Dolostone (made primarily of mineral Dolomite)
Limestone (made of calcite)
Calcite= CaCO3

Question 22

What are moderately strong sedimentary rocks?

Answer 22

Conglomerate (clastic sedimentary rock largely made up of gravel-sized chunks cemented together.

CLASTIC rocks: rocks composed of fragments
derived from preexisting rocks that are bound
together.

Question 23

What is a WEAK sedimentary rock

Answer 23

Mudstone (soft and brittle), made of fine particles of clay or mud deposited in aquatic environments

Question 24

Sandstone can be moderately strong or weak. Sandstone made up of sand grains are held together by a mineral cement. Cement can include:

Answer 24

Silica, calcite, iron oxides…

Question 25

What is degree of cementation

Answer 25

How well sand grains held together