Geology: Final

How is soil mainly produced?

through weathering

What is weathering?

physical and chemical breakdown of rocks

What is a soil profile?

collection of distinct layers parallel to the surface

how are soil profiles created?

vertical and horizontal movements

what is a soil horizon?

Layers in a soil profile

how can soil horizons distinguished?

Can be distinguished by soil color, texture and composition

How is soil color important?

Can be an important diagnostic tool for analyzing a soil profile, but can be misleading

what does a soils color mean?

The color is a function of its chemical and physical composition and processes within the profile

what does abundant organic material look like?

O and A horizons are dark

what does leaching of inorganic material (iron-bearing) look like?

E horizon is white

what does the presence of clay minerals and iron oxides look like?

B horizon varies from yellow-brown to light red-brown to dark red

what else can soil color indicate?

drainage

what does well drained soil look like?

red color \[air + water + iron -> iron oxide\]

what does poorly drained soil look like?

yellow color

what is soil texture?

fineness or coarseness of soils

whats the diameter of clay?

diameter < 0.004 mm

whats the diameter of silt?

0\.004 mm < diameter < 0.074 mm

whats the diameter of sand?

0\.074 < diameter < 2.0 mm

whats the diameter of gravel?

> 2.0 mm

smallest grain size to the largest?

Clay -> Silt -> Sand -> Gravel

what does saturated mean?

all the pore spaces in a block of soil are completely filled with water

what is moisture content?

amount of water in a soil

why is moisture content important?

Important to strength of soil and potential to shrink and swell

water flow: saturated vs unsaturated

Saturated flow if all the pores are filled with water, unsaturated flow otherwise (more common)

what is subsidence?

ground failure characterized by nearly vertical deformation or the downward sinking of earth materials

what is karst topography?

Dissolution of rocks beneath the surface

examples of subsidence?

Thawing of frozen ground, compaction of sediment, earthquakes and drainage of magma

why do soil volume changes occur?

Result from natural processes, changes in water content of soil, frost heaving

what are the typical forms of subsidence?

* Karst
* Thermokarst formation
* Frost Susceptible soils
* Sediment and soil compaction
* Earthquake
* Underground drainage of magma
* Expansive Soils
* Groundwater Removal

what is karst?

refers to landscape characterized by dissolution of bedrock by groundwater (chemical weathering)

why does dissolution occur?

Dissolution occurs as surface water or groundwater flows through rock that is easily dissolved

where is karst formed? what does it dissolve in?

* formed in limestone, dolostone, marble, gypsum, and halite
* dissolve in water (or weak acid)

what is this?

Dissolution of bedrock by acidic water

which areas are vulnerable to dissolution?

Areas underlain by dense, thin-bedded, fractured, or well-jointed crystalline limestone are especially vulnerable to dissolution

what are sinkholes?

crater like depressions caused by roof collapse or dissolution

what are the 2 types of sinkholes?

solutional sinkholes and collapse sinkholes

what are the characteristics of karst?

* Sinkholes
* Disappearing streams
* Caves
* Springs
* Karst Tower

when is a karst cave formed?

when dissolution produces a series of caves (groundwater moving)

what is a karst cave formation related too?

changing groundwater table as cave system tend to develop at or near the water table

what is frost heaving?

upward movement of soil particles and the land surface caused by volume increase

what happens during frost heaving?

soils containing water expand when frozen, moves the soil upward

what is permafrost? where does it occur?

Sediment remains frozen throughout the year, exists in polar or high altitude regions

what happens when permafrost melts?

it can create land subsidence

what does extensive melting create?

uneven soil called thermokarst

what has melted a large area over the past 5 decades?

Climatic warming

which soils and sediments can all possibly subside?

Rapidly deposited fine sediment, soil and sediment cemented with soluble minerals, and organic-rich soil

when does the rapidly deposited sediment compact?

when water is removed

when can compaction of sediment and soil occur?

naturally or as the result of human activities.

what do expansive soils do?

Expand during wet periods and shrink during dry periods

where is expansive soil common?

clay, shale, and clay-rich soil

what does expansive soil produce in surfaces?

Often will produce wavy landscape in surfaces, causing tilting and cracking of sidewalks, foundations of buildings

what causes expansive soils?

changes in its moisture content

Where does the majority of soil originate from?

It comes from weathered rock

What is the most important soil particle that characterizes expansive soils?

Clay minerals

What is the correct order of soil grain size from smallest to largest?

Clay, silt, sand, gravel

What does NOT cause ground subsidence?

Creation of permanently frozen ground where no thawing ever occurs

what is the coriolis effect?

earth rotates from west to east beneath the flowing air masses, caused a deflection or apparent change in motion of the wind

The unequal distribution of solar energy that reaches the surface of Earth leads to what?

temperature and pressure gradients that drive atmospheric circulation

how does the coriolis effect behave in the northern hemisphere?

it rotates in a counterclockwise manner => deflection is to the right

how does the coriolis effect behave in the southern hemisphere?

clockwise rotation => deflection is to the left

what is a cyclone?

an area or center of low pressure with rotating winds

how are cyclones classified?

* tropical or extratropical (extratropical: outside of the tropics) based on origin and core temperature
* both characterized by intensity, indicated by sustained wind speeds and lowest atmospheric temperature

Tropical cyclones

* Form over warm tropical or subtropical ocean water (5°– 20° latitude)
* Not associated with fronts (warm/cold air boundaries)
* Have warm central cores
* Tropical depressions, tropical storms, hurricanes
* High winds, heavy rain, surges, and tornadoes
* Derive energy from warm ocean water and latent heat

Extratropical cyclones

* Form over land or water in temperate regions (30°–70° latitude)
* Related to fronts. Associated with fronts and cool central cores
* Strong windstorms, heavy rains, surges, snowstorms, blizzards
* Typically Less severe, most don’t produce severe weather
* Derive energy from temperature contrasts along fronts

What are hurricanes?

Tropical cyclones in Atlantic and eastern Pacific Oceans (what we call them)

What are typhoons?

Tropical cyclones in Northwest Pacific Ocean (west of International Dateline and north of the equator)

What are cyclones (regional name)?

Tropical cyclones in Indian Ocean

What are nor’easters?

Extratropical cyclone that moves northward along East Coast of the U.S. and Canada

what is the Saffir-Simpson Scale?

Saffir-Simpson Scale classifies hurricanes based on wind speed and its damage-potential, developed by two meteorologists in 1970s

what are extratropical storms named after?

sometimes named after their origins

who names hurricanes?

Tropical storms and hurricanes given names established by international agreement through World Meteorological Organization

what are the rules for naming a hurricane?

* Named once winds exceed 63 km (39 mi.) per hour
* Names assigned sequentially each year from a previously agreed-upon list for each origin
* Male/female names alternated
* Names are reused every 6 years
* Names of big storms are retired (example: Katrina, Harvey)

what is a tropical disturbance?

* Most hurricanes starts out as TD
* Typically 200 - 600 km (120 to 370 mi.)
* An organized mass of thunderstorms persisting for > 24 hours
* Associated with elongated area of low pressure (trough)
* Has a weak rotation due to Coriolis effect

what are tropical disturbances formed by?

* Lines of convection similar to squall lines
* Upper-level low pressure troughs OR
* Cold front remnants
* Easterly waves of converging and diverging winds, such as Atlantic Ocean hurricanes

what are tropical depressions?

Tropical disturbance wind speeds increase and begins to spin, a low-pressure center is formed

what are tropical storms?

* Not all tropical depressions develop into tropical storm
* Sustained winds increase to 63 km (39 mi.) per hour
* Storm is given a name
* Wind speeds are not at hurricane strength, but rainfall can be intense

how are hurricanes classified?

Classified when winds reach 119 km (74 mph)

what are the environmental conditions of a hurricane?

* Thick layer of warm ocean water, at least 26 °C (\~80 F) & depth of 46 m (\~150 ft)
* Steep vertical temperature gradient, atmosphere must cool quickly with increasing altitude, which allows moist air to continues to be unstable and uplift
* Weak vertical wind shear (wind speed change), shear: Strong winds aloft prevent hurricane development
* Disturbance is far enough away from the equator, coriolis effect is strong enough to cause rotation around the region of low pressure

what are rain bands?

clouds that spiral inward around center, contains numerous thunderstorms, counter-clockwise in Northern Hemisphere, increase in intensity towards the center of the hurricane

what is the eyewall?

innermost band of clouds, contain the greatest winds and rainfall, constantly changing as the storm progresses

what is the eye of a hurricane?

area of calm at center of the hurricane, strong surface winds that converge towards the center never reach it, narrow at surface and wider at top, diameters range from 3 to more than 37 mi

where do tropical cyclones have the greatest impact?

Tropical cyclones have the greatest impact on coastal areas with warm offshore waters, such as the Gulf of Mexico and the Gulf Stream along the East Coast.

which area of the US has a higher risk for hurricanes and why?

The East and Gulf Coasts of the United States have the highest risk for tropical storms and hurricanes in North America, moving direction: tend to move west-northwest, temperature: 80s F vs 70s F

which is more active: Northwest pacific or north Atlantic

Northwest Pacific is much more active than North Atlantic (3X)

why do the South Atlantic and southeast Pacific rarely have hurricanes?

because of cold ocean water

why do hurricanes not form close to the equator?

because of the absence of the Coriolis effect

whats the risk of extratropical cyclones in the US?

* Severe weather from extratropical cyclones is greater in the interior of the continent but may also occur in coastal areas.
* Creates winter storms along Pacific Coast and snowstorm in Nevada, Rocky Mountains
* Spring and summer thunderstorms and tornadoes in United States and Canada

What is a typhoon?

A hurricane in the Western Pacific Ocean, such as Japan and China

What is the primary difference between a tropical depression and a tropical storm?

Wind speed

What is the correct order of tropical cyclone development (least to most developed)?

Tropical disturbance, tropical depression, tropical storm, hurricane

Which of the following locations has the least risk for hurricanes: Florida, Texas, California, New Jersey?

California

What is climate?

characteristic atmospheric conditions over a long period of time (years or decades)

What is weather?

atmospheric conditions over a short period of time (days or weeks)

What is the atmosphere comprised of?

mainly of nitrogen and oxygen with smaller amounts of other gases

What are permanent gases?

* Gasses whose proportions stay constant
* Nitrogen(N2 ), Oxygen(O2 ) and Argon(H2 )
* Have little effect on atmospheric dynamics

What are variable gases?

* Gasses whose proportions vary with time and space
* Play important roles in atmospheric dynamics
* Carbon dioxide, water vapor, ozone et.

What are aerosols?

* Microscopic particles whose proportions vary with time and space
* Not a gas, but microscopic liquid or solid particles (from dust, or fossil fuels)

What is a cryosphere?

* The part of the hydrosphere where water stays frozen year-round
* Permafrost, sea ice, ice caps, and glaciers

Where do glaciers flow?

Glaciers flow from high areas to low areas under the weight of accumulated ice

What is a glacier input?

new snow forms ice at high elevations