Gravity

The processes that transport large quantities of earth materials down slope

Water Saturation- water fills pore spaces

Angle of repose- maximum angle at which a slope of loose material will lie without cascading down

Vegetation- plants add slope stability by protection against erosion

& Earthquakes

Fall- solid blocks of rock fall rapidly from a steep or vertical slop, ONE UNIT FAST ROCK

-Talus is debris

Slide- single mass of rock or sediment is released and moves rapidly along a plane of weakness, ONE UNIT MODERATE ROCK

Flows- fluid mass movement high water content

Debris avalanche is fastest, mixed with air

Creep vs. Rock Avalanche:

Creep- slowest mass wasting process, unconsolidated material moves slowly downslope under the influenceof gravity, FLUID VERY SLOW UNCONSOLIDATED

Causes once vertical objects to slant over time

Rock Avalanche-flows by entraining air as it moves down slope, FLUID FAST ROCK

ex. Air hockey table

Nature of Slope Material:

-Solid rock may be reduced by deformation, physical, chemical weathering

-Sedimentary rocks with bedding planes

-Foliated metamorphic rocks

What are the triggers for mass wasting? 

Can human activity trigger mass wasting? How?

Weathering, Physical erosion, Faults/Folds (tectonic activity)

Human Activity: added mass of building on slopes, removal of vegetation, increasing angle of slopes, addition/removal of water

Chapter 14:

Running Water: The Geology of Steams and Floods

How do rivers and streams fit into the hydrologic cycle? 

-run off vs. infiltration

run off is when water returns to the sea

infiltration makes weak surfaces underground more slippery

Not all runoff flows into rivers, much of it soaks into the ground as infiltration

What are the different water reservoirs? Be able to place them in order from largest to smallest?

ocean

glacier 

groundwater

Dissolved load- in solution (ions)

Suspended load- in suspension (finer particles that are suspended in water column, murky muddy)

Bed load- along the bottom (large particles, sliding rolling saltation (bouncing))

Movement of bed load forms ripple marks at LOW velocity

Movement of bed load forms dunes at HIGHER velocity

Straight- fast flowing, mountain streams (steep slopes), straight segments

Braided- multiple channels, split and rejoin, carries high amounts of sediment, high velocity at terminus of glacier

Meandering- one main trunk winds back and forth across flood plain, low slopes (low velocity) through easily eroded bedrock (low suspended sediment)

Drainage basin- area of land which funnels all the water into streams draining the area

Drainage divide- ridge of high ground along which all rainfall runs off down one side of the rise or the other

Dendritic- flat lying layers (similar rock type)

Looks like tree

Trellis- folded rock layers

Rectangular- rock units cut by joints or faults

Radial- high mountain peak (volcanoes)

 Point with streams coming off it (like a flower)

Velocity is higher in the middle of the stream, in a meandering stream the high velocity area bumps against the points of the stream causing high erosion. Cut banks form in the inside bends where the velocity is slower, depositing materials.

Meandering streams change as erosion increases, cutting bigger bends. In floods, new streams can form connecting bends, and cutting off the larger bends to become oxbow lakes, IF two bends are close by they will connect

Velocity- speed of the stream

-Distance over Time

Gradient- rise over run (slope)

-Feet per mile

Discharge- the volume of water flowing past a certain point in a given unit of time (typically cubic feet per second or CFS)

Floodplain- area covered in water during flooding,fine sediments are deposited at the outer parts of the floodplain

Levees- during a flood the thickest and coarsest sediments are deposited at the channel edges

Terraces—mark previous level of floodplain, formed by renewed down cutting to lower base

Alluvial Fans- fan shaped accumulations of sediment

Form where streams adjust velocity when leaving a narrow valley for a broad relatively flat area

Bajada- multiple alluvial fans that have merged

Deltas—triangular shaped deposits of sediment deposited as streams enter the ocean (slow velocity)

Recurrence interval-

the average time between two floods of a given magnitude

Depends on climate, width of floodplain, channel size

5% it will happen this year, 5% next year

(graph oh study guide)

Water enters the hydrologic cycle by evaporating from the earth's surface and rising into the atmosphere. After a period of time, this water condenses and falls back down in the form of rain or snow.Some of this rain or snow stays on the land and surface water. Gravity then plays its part in making allthe surface water run down the slope. This running water collects in stream sources and are moved from the higher to lower elevation.

1) Condition and type of surface materials 

2)Vegetation  

3)Topography 

4)Precipitation

Unsaturated zone and Saturated zone: how far you dig until you reach water
Water table: boundary between unsaturated and saturated zone. It is not constant
Porosity: total volume of pore space in a sediment or rock
Permeability: The ability of water to flow through spaces in rock
Aquifer: the space between two aquitards, is not open to the surface.
Unconfined Aquifer: open to the surface (saturated and unsaturated zones) with a water table
Aquitard: bed or rock through which water cannot move or move slowly
Artisian Well: Penetrates confined aquifers in which water is under enough pressure to rise above the surface on their own. Water flows freely without help

Recharge: When water enters or re-enters the ground

Consider the following 6 rock/sediment samples. Which sample/samples have high or very high porosity? Which has the highest permeability? Which sample/samples would be most likely to form aquifers? Which sample/samples would form aquitards?

Gravel- High permeability high porosity 

Clay= low permeability low permeability. 

Porosity-total volume of pore space in sediment or rock 

High perm=lots of water

Permeability-the ability of water to flow through spaces in rock and sediment 

Sample A - well-sorted, coarse-grained unconsolidated sediments.(high)

Sample B - very poorly sorted unconsolidated sediments.(very high)(highest permeability) 

Sample C - highly fractured basalt (very high) 

Sample D - unfractured granite, with no vesicles (low) 

Sample E - unfractured mudstone /shale

Sample F - very well cemented sandstone

Cone of Depression: Occurs when water in pulled out of an aquifer faster than it can recharge.

Subsidence: When large amounts of ground water have been excessively withdrawn from an aquifer

Saltwater intrusion: The movement of saline water into fresh water aquifers. Can lead to contamination of drinking water sources.

What is the difference between hot springs and geysers? What heats the water of hydrothermal activity? What is the source (plate boundary or hot spot) of heat for the geysers of Yellowstone?

What is karst? How is it related to groundwater? In which rock type does karstmost commonly form?

Describe the features of karst (below and above the earth’s surface)

deformation mechanism- grain-to-grain contact

Caves are formed primarily in limestone which dissolves in acid including the slightly acidic water that is naturally found in many groundwater reservoirs.

What are speleothems? How do they

form? Speleothems are made of which mineral? How does it form caves? How do stalactites differ from stalagmites? 

speleotherms- features formed through water based deposits of CaCO3

stalactites and stalagmites are considered speleotherms

stalactites-top

stalagmite- bottom

How do we know what the seafloor is like?

Explain how man has been able to map the seafloor

we mapped it through a variety of ways

-early navigators used a lead line survey

-used LIDAR and bounce light off of the ocean bottom to get a more detailed picture

-best way is through satellite laser imagery. The ocean surface hints at what is under water and lasers can be used to measure the height of the ocean at different spots to within inches.

Haveportions of the continental shelf ever been exposed at the surface?

If so, when might this occur and how might this change its surface? 

Does the continental shelf area have any economic importance? Please explain

The continental shelf comes to the surface at convergent boundaries. It is found as blueschist evidenced as shells found at peaks of the himalayan mountains.

During convergence the sea floor moves up as an accretionary wedge or as nonvolcanic mountains.

The continental shelf is important economically because it is an area where metallic ores hydrocarbon and oil are very frequently removed.

Identify the type of mass movement of sediment which occurs along the continental slope and rise. What submarine features do they give rise to?

Waves form through wind. The stronger the wind, the higher and bigger the waves.

Wavelength: The distance between crests 

Wave height: vertical distance between the crest and trough. 

Wave period: time between successive waves to pass

Swash zone: zone where water comes on beach from a wave.

Gravity causes breakers as the top of the wave gets too high.

Longshore Current: where waves arrive at the shore obliquely. This moves sediment because it moves in a sawtooth pattern that results in gradual transport of the beach sediment parallel to the beach. 

A rip current is a seaward strong flow perpendicular to the beach.

Wave cut: when wave erosion gradually undercuts a cliff face.

Platform: terrace

Sea stacks: because the refraction waves attack the sides of a headland, slowly eating through it creating a sea arch. Eventually this arch collapses leaving sea stacks.

Tombolo: A depositional landstructure as an island that is connected by a narrow land bridge like a spit.

Sand spits: the coastland idents landward, beach drift stretches beaches out into open open water to create a sand spit.

Barrier Islands: in regions with an abundant sand supply offshore bars rise above the mean high water level and become barrier islands.

How do seasonal changes affect beach profiles? 

Man-made structures like groins, breakwaters, jetties are used to prevent beach erosion. In general what is there affect where there constructed? And the affect down-current (down coast) of the structures?

When humans add structures in order to slow erosion sediments typically become piled and downstream is quickly eroded away.

When other approaches are taken (beach nourishment, land use planning) erosion is typically not caused in new areas.