GEO CO4

we start the grind early nau

Mass Wasting

Mass Wasting

is the downhill movement of masses of bedrock, rock debris, or soil driven by the pull of gravity

• It is the most easily avoidable of all major geologic hazards

(There is Flow, Slide, and Fall)

Gravity

the driving force for mass wasting

Steep slopes

shear forces maximized by gravity

Shear Strength

resistance to

movement or deformation

true

Saturated soil has reduced shear strength due to increased pore pressure

true/false

Creep

very slow downslope movement of soil

Flow

descending mass moves downhill as a viscous fluid

Earthflow

debris moves

downslope, slowly or rapidly,

as a viscous fluid

Solifluction Permafrost

flow of water-saturated soil

over impermeable material.

• Common in colder

climates.

Mudflow

soil and water flowing down a channel

Debris Flow

flowing mixture of debris and water, usually down a channel

Falls

material free-falls or bounces down a cliff

Rockfall

a block of bedrock breaks free and falls or bounces down a cliff

Talus

fallen Rock fragments that accumulates off a cliff base

Slides

descending mass remains relatively intact, and descends along

well-defined surfaces

false

Underwater Landslides CAN’T create a tsunami (true/false)

Rockslide and rock avalanche

rapid sliding of a mass of bedrock

along an inclined surface of

weakness

false

Steeper slopes are better to prevent landslides (true/false)

Hydrologic Cycle

the movement and interchange of water between sea, air, and land

transpiration

evaporation from plants in the hydrologic cycle

runoff

water flowing over land surface in the hydrologic cycle

infiltration

water soaking into the ground in the hydrologic cycle

Stream

body of running water, confined to a channel that runs downhill

headwaters

upper part of stream

mouth

place where a stream enters a larger water body, (end of stream)

channel

long, narrow depression eroded by stream

stream banks

sides of channel

floodplain

flat valley floor composed of sediment deposited by the stream

streambed

bottom of the channel

Tributary

a small stream flowing into a larger one

Drainage basin

the total area drained by a stream and its tributaries

divide

ridge or high ground that divides one drainage basin from another

continental divide

separates the streams that flow into the pacific from those that flow into the atlantic and gulf of mexico

drainage pattern

the arrangement/map view of a stream and its tributaries

dendritic

drainage pattern resembling the branches of a tree

radial pattern

streams diverge outward in a circular pattern

rectangular pattern

tributaries have frequent 90 degree bends

trellis pattern

parallel streams with short tributaries meeting at right angles

Center

Maximum velocity of stream happens at the _________ of the channel

true

higher velocity of streams promote erosion (true/false)

discharge

volume of water passing a particular point in a stream over time

hydraulic action

stream has the ability to pick up and move rock and sediments

solution

dissolving of rocksa

abrasion

grinding away of stream channel by the friction and impact of the sediment load

potholes

are eroded into the steam bed by the abrasive action of the sediment load in the stream

bed load

large/heavy particles that travel on streambed

traction load

large particles that travel ALONG streambed by rolling, sliding, dragging

saltation load

medium particles that travel by bouncing along steambed

suspended load

small/light sediments that remains above the stream bottom by turbulent flow for an indefinite period of time

dissolved load

dissolved ions produced by chemical weathering of soluble minerals upstream

bars

sediments TEMPORARILY deposited along stream course

placer deposits

concentrated heavy sediment

braided streams

contain sediment deposited as numerous bars around which water flows in highly interconnected rivulets.

they look intertwined/braided

common for streams with a lot of sediment

meanders

rivers with sinuous curves

cut banks

Water flows faster along the outside of bends causing erosion and

created ________

meander cutoffs

form when a new channel is cut through a meander

floodplains

are broad strips of land built up by sedimentation on either side of a stream channel

natural levees

Main channel has slightly raised banks with

respect to the floodplain known as _________

Delta

body of sediment deposited at the mouth of a river when flow velocity

decreases

Alluvial fan

large, fan – or cone-shaped pile of sediment that forms

where stream velocity decreases as it emerges from a narrow mountain

canyon onto a flat plain

Well – developed in desert regions, such as the southwestern U.S.

• Larger ones show grading from large sediments nearest the

mountains to finer sediments farther away.

Valleys

most common landform on earth

formed by steam erosion

downcutting

process of deepening a valley by erosion of the streambed

V shaped valleys

formed from downcutting with mass wasting and sheet erosion

false

streams CAN erode below their base level (true/false)

Graded streams

– have concaveup longitudinal profile

Lateral erosion

widens stream valleys by undercutting of stream banks and valley walls as stream swings from side to side across the valley floor

Headward erosion

the slow uphill growth of a valley above its original source by gullying, mass wasting, and sheet erosion

stream terraces

step like landforms found above a stream and its floodplain

• sudden change from deposition to erosion

Incised meanders

Meanders that cut further vertically downward.

deeper than regular meanders

• May be produced by profound base

  level changes, as when rapid tectonic

  uplift occurs.

Flooding

when water levels rise and overtop the banks of a river

flash floods

local, sudden floods of large volume and short duration

dams

trap flood waters in reservoirs upstream and release it gradually

artificial levees

increase capacity of a river channel and works well until stream overtops leeves, which then leads to rapid flooding and erosion

tldr they suck

Wise land use planning

most effective flood risk prevention action

gradient

The downhill slope of a streambed, and it controls the stream velocity

true

meanders happen In a stream's lower reaches (true/false)

false

Lateral erosion widens the stream channel.
(true/false)

ungraded stream

A stream that has an irregular longitudinal profile with rapids and waterfalls along its course

ground water

lies beneath the ground surface, filling pores in sediments and sedimentary rocks and fractures in other rock types

saturated zone

subsurface zone in which all rock openings are filled with water

water table

top of the saturated zone

unsaturated zone

unsaturated region above the water table

perched water table

above and separated from main water table by an unsaturated zone

• Commonly produced by thin lenses

  of impermeable rock (for example,

  shale or clays) within permeable

  ones

porosity

the percentage of rock or sediment that consists of

voids or openings

Measurement of a rock’s ability to hold water

Permeability

- the capacity of a rock to transmit fluid through

pores and fractures

• Interconnectedness of pore spaces

impermeable

Granites, schists, unfractured limestones are ___________

aquifer

body of saturated rock or sediment through water can move easily

unconfined aquifer

has a water table and is only partl yfilled

confined aquifer

completely filled with water under pressure

aquitard

rock/sediment that retards ground water flow due to low porosity and/or permeability.

• shale, clay, unfractured crystalline rocks.

Flow Velocity

This depends on the slope of the water table, and permeability of the rock or sediment

well

a deep hole dug or drilled into the ground to obtain water from an aquifer

Drawdown

water table can be lowered by pumping, this process is called ___________

artesian well

water may rise to a level above the top of a confined aquifer producing an ________

spring

a place where water flows naturally from rock or sediment onto the ground surface

gaining streams

receive water from saturated zone

losing streams

lose water to the saturated zone

false

Stream beds lie BELOW the water table (true/false)

Maximum Infiltration

occurs through streambed producing permanent “mound” in the water table beneath dry channel

Subsidence

Dropping water table can lead to ground _________

= this can lead to cracked foundations, rocks and pipelines