EARTH SCIENCE REGENTS REVIEW



EARTH SCIENCE REGENTS REVIEW

TOPIC 1: OBSERVATION AND MEASUREMENT OF THE ENVIRONMENT

* Observations involve using the senses to gather information -- all the senses, not just sight

* Our senses are limited (ex/ we can only see so far) so observations can be improved by extending the senses through the use of instruments (telescopes, meter sticks, etc.)

* Inferences are conclusions or predictions based on observations (they may or may not be accurate)

EX/ observations about a mineral: 3 planes of cleavage, clear, tastes salty

inference: the mineral is halite

* Classification is the grouping of things according to similar properties, or, organizing things to make studying them easier [by classifying things based on good observations, we make valid inferences]

UNITS OF MEASUREMENT

* mass: the amount of matter in an object, measured in grams

* weight: a measurement of the amount of gravity pulling on an object -- it depends on the object’s distance from the Earth’s center [mass doesn’t change as you leave the Earth, but weight does (“weightlessness”)] For objects located at or near the Earth’s surface, mass is measured by weighing the object

DETERMINING ERROR IN MEASUREMENT

* percent error / percent deviation {formula in Reference Tables}

Write out the formula! Then plug in numbers! Most often, people forget to multiply by 100......

If you write out the formula and then plug in numbers, you won’t miss any of the steps!

EX/ The actual mass is 100 grams and the measured mass is 95 grams. (remember, the word “difference”

means “subtract” the numbers!) Difference between actual / accepted and the measured values is 5

grams; divide 5 grams by the actual/accepted value of 100 grams and you get .05. Now, multiply this

by 100 and you get 5% error

DENSITY

* Density = mass per unit of volume (or mass ÷ volume) {formula in RT} (mass is in grams, volume is in cm3, cc, or ml)

* When the density is given and you have to determine either mass or volume, use the density formula, put Density over 1.0 and plug in given values, then cross multiply. On a multiple choice question, use trial and error: ex/ if density and mass are given in the problem and you have to find the volume, plug in each volume choice given and the mass into the density formula and see which one comes up with the value for density that they gave you. ALWAYS DOUBLE CHECK!!!!!!!!

* Remember, the density of a substance doesn’t change if it is cut up smaller or more of it is added!

EX/ If something has a mass of 100 g and a volume of 50 ml, the density is 2 g/ml.

If it is cut in half, mass = 50 g, and volume = 25 ml, the density is still 2 g/ml

If it is doubled in size, mass = 200 g, and volume = 100 g, the density is still 2 g/ml

* Density only changes if the temperature or pressure changes

* Temperature: if you increase the temperature, molecules move around more, taking up more space/volume -- so the density decreases (ex/ smoke rises, a hot air balloon)

* Pressure: if you increase pressure, you compact the same amount of matter into smaller space/volume -- so the density increases (ex/ basketball vs. bowling ball) This rule applies mostly to gases (because molecules are more free to move) and less to liquids and solids.

* Most materials are most dense in the solid phase (molecules are packed closer together)

* Water is the exception -- most dense as a liquid at 4oC {on RT}

* Energy exchange occurs along an interface: where materials with different properties meet (ex/ wind & waves)

* Dynamic equilibrium: a state or condition of balance (look for key words: “same,” “equal,” or “balance”)

[the Earth as a whole is in a state of dynamic equilibrium, but it is altered by human activities]

* Relationships: plug in numbers on the graph, make X’s, connect X’s with a line

• direct relationship: both things increase together or decrease together

• inverse relationship: one thing increases while the other decreases

• constant / no relationship: one thing stays the same as the other thing changes

TOPIC 2: MEASURING THE EARTH

* The Earth’s true shape is an oblate spheroid (“squashed sphere”) -- bulging at the equator and flat at the poles

[you weigh less at the equator because you are farthest from the center of the Earth]

* The bulging, however, is so small that it can barely be noticed -- therefore, the best model for the shape of the Earth would be something that is perfectly round and smooth -- like a billiard ball or ping pong ball

* Evidence for the Earth’s shape comes from:

• The altitude of Polaris -- if the Earth were flat, the altitude of Polaris would always = 90o

• Gravity measurements -- gravity is slightly less at the equator, slightly more at the poles

• Lunar eclipses -- the curved shape of Earth is seen as a shadow on the moon

• Ships disappear over the horizon from the bottom up

* The best evidence for the true shape of the Earth is actual photographs of the Earth from space

EARTH’S ZONES

* Atmosphere: layer of gases surrounding the Earth (divided into several layers, on RT)

* Hydrosphere: layer of liquid water surrounding the Earth (think “hydroelectric power”, “dehydration”)

* Lithosphere: layer of solid rock surrounding the Earth

LATITUDE AND LONGITUDE

* Latitude lines go across (think “lat / flat” or “lat / ladder”) and measure locations north or south of equator

[also called parallels, because all latitude lines are parallel to each other]

* Longitude lines go up and down (all lines are long) and measure locations east or west of prime meridian [also called meridians] [prime meridian goes through Greenwich, England]

* Equator = 0o latitude ; Prime Meridian = 0o longitude; International Date Line = 180o longitude

* Remember when determining the directions of north, south, east and west: east and west spell “WE”

* Time is determined by longitude (think of the longitude lines that make up time zones for TV programs) Since the Earth rotates 360o (one circle) in 24 hours, 360 ( 24 = 15o per hour -- so for every 15 degrees of longitude, time changes one hour -- ahead on the clock if the location is east, behind on the clock if the location is west (think of California on the west coast being behind us on the clock)

* If the time is known in Greenwich and the time is known where you are, you can determine longitude

EX/ It is 3 p.m. in Greenwich and 7 p.m. where you are. The difference in time is 4 hours. For every hour,

there is 15o of longitude. 15 x 4 = 60. Since you are ahead on the clock, you are east of Greenwich, so

you are at 60o East longitude.

EX/ It is 7 a.m. in Greenwich and you are at 45o West longitude. 45 ( 15 = 3, so your time is 3 hours

different from the time in Greenwich. You are west, therefore you are behind on the clock, so it is 4 a.m.

where you are.

* Latitude is measured by the altitude of Polaris in the Northern Hemisphere (Polaris is the North Star and can’t be seen in the Southern Hemisphere) Your latitude is equal to the altitude of Polaris!!!!!!

EX/ Where you are, Polaris is found at an angle of 38 degrees above the horizon -- you’re at 38o N lat.

[on the equator, altitude of Polaris = 0o; at the North Pole, altitude of Polaris = 90o]

FIELDS

* Isoline: a line connecting points of equal value -- they never cross!

* Gradient is shown by the closeness of isolines -- lines close together = steep gradient {formula on RT}

* Contour interval: the difference in elevation between adjacent contour lines

* To determine which way a stream is flowing on a contour map:

1. streams always flow downhill -- look for higher elevations for the source of stream, flowing toward lower

elevations

2. contour lines always point (bend) upstream

* Remember: when measuring the distance between two points, always use a scrap piece of paper and make several measurements along straight portions of the route, turning the paper as you go.

TOPIC 3: EARTH IN THE UNIVERSE

* The Earth is a planet which revolves around the Sun. The Moon is a satellite that revolves around the Earth. The Sun is a star. The nine planets {RT} and their moons, as well as the asteroids between the planets, revolving around our Sun make up the Solar System.

* Our Solar System is one of billions within our galaxy, The Milky Way. The Milky Way is one of billions of galaxies in the universe.

* The Big Bang Theory is the most widely accepted theory for the creation of the universe. It basically states that all matter and energy started out concentrated in a small area and, after a gigantic explosion, matter begin to organize into subatomic particles and atoms. This is believed to have occurred approximately 15 billion years ago. Evidence for the Big Bang includes the fact that galaxies are moving away from us and each other.

* The Doppler Effect is the shifting of wavelengths (colored lines) in a spectrum due to an object moving toward or away from the observer.

( If the object is moving toward the observer, the electromagnetic waves are bunched together resulting in a blue shift.

( If the object is moving away from the observer, the electromagnetic waves are spread out resulting in a

red shift.

* The Milky Way galaxy is about 100,000 light years across and has a spiral shape. We are located towards the end of a spiral arm.

* A light year is the distance light travels in one year (9.5 trillion kilometers)

* The Sun is an average star (part of the Main Sequence) and is about half-way through its life cycle. It gets its energy from nuclear fusion reactions in which hydrogen nuclei combine to form helium nuclei, giving off tremendous amounts of energy

* Luminosity refers to a star’s brightness, compared to the Sun, if it were the same distance as the Sun. Generally, hotter stars have a color toward the blue end of the spectrum and a greater luminosity {RT}

* Stars are formed in gas and dust clouds (nebulae) and go through stages, depending mostly on their mass. They start out as a main sequence star, then explode into either a red giant or a supergiant, depending on the mass. A red giant may then collapse into a white dwarf and then a black dwarf (dead star). A supergiant could explode into a supernova and become either a neutron star or a black hole.

* The Solar System is about 4.5 billion years old. Individual planetary characteristics are in the Reference Tables.

* A geocentric model of the solar system has the Earth at the center, with planets, moon, and sun revolving around it in circular orbits (this was the first model of the solar system)

* A heliocentric model of the solar system has the Sun at the center, with planets moving around it, and the moon moving around the Earth, all in circular orbits, and the stars stay in one place

* The heliocentric model was improved by Kepler’s elliptical orbits, which explained why heavenly objects appear to change in size.....because our distance from them changes (objects that are closer appear to be bigger)

KEPLER’S LAWS

* The eccentricity of an ellipse (elliptical orbit) can be determined by dividing the distance between foci by the length of the major (longest) axis of the ellipse {formula on RT}. It is always a value between zero and 1.0. Use the centimeter ruler on the cover of the RT.

[eccentricity is how “flat” a circle is, therefore, if the eccentricity value is close to zero, it’s close to a perfect circle; if the value is close to 1.0, it is very “flat” or “eccentric”]

* The Earth’s orbit is a slightly eccentric ellipse

* If the Earth’s orbit was a perfect circle, it would always travel at the same speed around the Sun. Because it is elliptical, sometimes the Earth is closer to the Sun (January) so it travels faster and the Sun appears larger. When it is farther from the Sun (June) it travels slower and the Sun appears smaller.

* The larger the radius of a planet’s orbit, the longer its period of revolution [also stated: the farther a planet is from the Sun, the longer it takes to get around it]

* Gravitational force between two objects depends on the masses of the objects and the distance between them. {formula on RT} Since distance is squared in the formula, distance has more effect on gravitational force than mass. Mass and force have a direct relationship: as mass increases, force of attraction between the objects increases. Distance and force have an inverse relationship: as distance between objects increases, force between them decreases.

* When a planet is closest to the Sun, its speed is greater, force of attraction is greater, kinetic energy is greater

TOPIC 4: THE EARTH MODEL -- EARTH MOTIONS

* The apparent daily motions of the stars, moon, sun, and planets are due to the Earth’s rotation -- so everything moves generally from east to west at approximately 15o per hour (the speed the Earth rotates)

* Rotation: spinning on an axis

* Revolution: orbiting around an object

[if you get confused, look up the Solar System Data Table in the Reference Tables -- when you see that the Earth’s period of rotation is 24 hours, you will realize that a “day” is caused by spinning; when you see that the Earth’s period of revolution is 365 days, you will realize that a “year” is caused by orbiting the Sun]

PHASES OF THE MOON

* Remember to put yourself on the diagram of the Earth and it may be necessary to turn your paper around

* The Earth, Sun, and Moon are rarely on the same plane -- even though once each month the Moon is between the Earth and Sun, which would produce a solar eclipse, they are not usually at the same level -- the Moon may be much higher than the Earth and therefore not in the path of the Sun’s rays

* Solar eclipses occur at New Moonand are seen during the day; lunar eclipses occur at Full Moon and are seen at night

* The moon revolves once around the Earth in 27.3 days. It also rotates once on its axis in 27.3 days. This is why we always see the same side of the moon [periods of rotation and revolution are equal]

* In the time it takes the moon to make one revolution around the Earth, the Earth has also moved around the Sun, so it takes the moon a little while longer to “catch up” to the Earth and be in the same phase again -- the moon’s cycle of phases takes 29.5 days

* The phases of the moon are caused by the moon’s revolution around the Earth

* Tides are cause by the Moon’s gravitational pull on the Earth. There are two high tides and two low tides every day (each is about 6 hours apart). When the Moon is New or Full, the Sun and Moon are pulling together resulting in extreme tides called Spring Tides. When the Moon and the Sun are at right angles to the Earth during the Quarter phases, the result is moderate tides which are called Neap Tides.

EARTH’S REVOLUTION AND SEASONS

* The Earth is tilted 23½o from the plane of its orbit; therefore, the Sun’s direct rays hit the Northern hemisphere when the Earth is tilted toward the Sun, and they hit the Southern hemisphere when it’s tilted away. When it’s titled neither toward or away from the Sun, the Sun’s direct rays strike the equator.

* In summer in the Northern hemisphere (June 21), the Sun appears to rise a little north of east and set a little north of west. This causes a longer arc (path) in the sky producing our longest period of daylight and the time when the noon Sun reaches its highest point (altitude) in the sky. The North pole has 24 hours of daylight on this date.

* In the northern hemisphere, the noon Sun is always due south

* In winter in the Northern hemisphere (December 21), the Sun appears to rise a little south of east and set a little south of west. This causes a shorter arc (path) in the sky producing our shortest period of daylight and the time when the noon Sun reaches its lowest point (altitude) in the sky. The North pole has 24 hours of darkness on this date.

* Summer solstice: June 21

* Winter solstice: December 21

* Equinox: March 21 and September 23 -- when neither pole is tilted toward the Sun, the Sun’s direct rays are on the equator, and every place on Earth has 12 hours daylight and 12 hours darkness (think of equal days on the equinox)

* Zenith: the point directly overhead (90o angle) [remember: the Sun can never be directly overhead anywhere beyond the tropics (23½o north or south of equator)]

* The Earth is actually closer to the Sun in December (perihelion) and farther from the Sun in June (aphelion)

* The seasons on the Earth are caused by:

1. the Earth’s revolution around the Sun

2. the tilt of the Earth’s axis [if the Earth were not tilted, we would have no seasons because no time of the year would receive more sunlight than another; if the Earth were tilted more, we would have a larger difference in the amount of sunlight received so winters would be colder and summers would be hotter]

3. the parallelism of the Earth’s axis (the North pole always points to Polaris)

TERRESTRIAL OBSERVATIONS

* The velocity of the Earth’s rotation increases as you move from the poles toward the equator (more distance to cover in the same amount of time)

* Evidence of the Earth’s rotation:

1. foucault pendulum -- although the pendulum appears to be changing direction, it is actually swinging in the same direction but the Earth is rotating under it

2. coriolis effect -- fluids (free-moving substances like liquids and gases) appear to be deflected to their right in the northern hemisphere. Keep in mind that the object is deflected to the right of its intended path, not your right!

TOPIC 5: ENERGY IN EARTH PROCESSES

* Electromagnetic energy is radiated (given off) by all objects -- generally, the higher the temperature, the more energy radiated

* The different types of electromagnetic energy from the Sun make up the “electromagnetic spectrum” {in RT}

* At a temperature of absolute zero (-273oC or 0o Kelvin), an object would radiate no energy, but this temperature is a theory -- it has never been reached

* Wavelength: the distance between crests of a wave

* Electromagnetic energy waves travel at the speed of light

* Infrared energy: heat

* When electromagnetic waves come in contact with something, they can be:

• refracted (bent as they pass through)

• reflected (bounced back)

• scattered (dispersed in several directions)

• absorbed (kept inside the object)

• transmitted (pass through completely unaffected)

[the type of energy (wavelength) and the type of material the energy encounters determine what will happen. For instance, visible light at a short wavelength can be transmitted through clouds unaffected, but infrared (heat) energy at a longer wavelength will get absorbed by a cloud.]

* Energy can be transferred from one place to another by:

• conduction -- molecules vibrate and collide, passing on energy as they move [this works best with solids because molecules are close together] (think of molecules as box cars and the train conductor)

• convection -- molecules move because of differences in temperature which cause differences in density: hot ones rise, cold ones sink [this works best with gases and liquids where molecules are free to move around] (think of a convection oven: air circulates in the oven)

• radiation -- requires no molecules to move, just energy waves [ex/ sunlight, starlight]

* Latent heat: potential energy gained or lost during a change in phase [ex/ when boiling water, the temperature doesn’t change -- stays at 100oC -- the heat being added is used to break molecular bonds and change the water into water vapor]

* It takes more energy to change water to water vapor than ice to water {values are in RT}

* If heat is being added, the substance gains energy; if heat is being released, the substance loses energy (think of the fact that you have to heat ice to melt it and heat water to boil it and get steam -- adding heat)

* Law of Conservation of Energy: Energy is never created or destroyed -- the amount of energy lost by a source equals the amount of energy gained by a sink (easiest to see in a closed system)

* Specific heat: the amount of heat energy involved in changing the temperature of one gram of a substance one degree Celsius {chart on RT -- the lower the specific heat, the less energy needed, therefore, its temperature changes rather quickly}

* Liquid water has the highest specific heat of any naturally occurring substance (so everything else heats up and cools down faster than water -- when the same amount of energy is applied)

* An object that is a good absorber of energy (gets hot fast) is also a good radiator (cools down fast) of energy

GREENHOUSE EFFECT

* The greenhouse effect is when short wavelength visible light energy {this is in RT} enters the atmosphere, gets absorbed by the Earth’s surface, and is reradiated as longer wavelength infrared heat energy. Water vapor and carbon dioxide in the atmosphere absorb the heat, trapping it in the atmosphere, thus warming up the Earth. It is called the “greenhouse effect” because the same thing happens to light, heat, and glass in a greenhouse. It is a concern because burning fossils fuels and destroying rain forests increases the amount of carbon dioxide in the atmosphere, thus increasing the amount of heat trapped in the atmosphere and causing the Earth’s temperatures to rise (at least in theory).

TOPIC 6: INSOLATION AND THE EARTH’S SURFACE

* Insolation: incoming solar radiation (radiation from the Sun that reaches Earth)

* The greatest intensity of insolation is in the visible light wavelength part of the spectrum

* Intensity of insolation increases with an increase in the angle of the Sun’s rays (greatest intensity of the day occurs at noon when the sun is highest in the sky; greatest intensity for the year occurs for us on June 21 when the Sun reaches its highest altitude in the sky)

* The angle of the Sun’s rays depend on latitude and season (we have summer in June - July because the angle of the Sun’s rays is greatest; southern hemisphere has winter then because Sun’s rays are at a lower angle. The poles never get very warm because the angle is never very high)

* Duration of insolation: length/hours of sunlight -- the longer the Sun’s path in the sky during the day, the longer the period of daylight (June 21 is longest for northern hemisphere)

* Insolation raises the Earth’s temperature, terrestrial radiation (heat given off by the Earth) cools it down

* At night, when terrestrial radiation exceeds insolation, the temperatures drop

* Minimum (lowest) surface temperatures usually occur one hour before sunrise

* Maximum (highest) surface temperatures usually occur two hours after solar noon

* Yearly maximum surface temperatures usually occur about six weeks after the time of maximum insolation (August 1 in northern hemisphere) because for six weeks, the amount of insolation is still greater than the amount of terrestrial radiation. [weather systems can alter these dates and times slightly]

* Visible light passes through the atmosphere virtually unaffected

* Most of the ultraviolet light is absorbed by ozone in the atmosphere

* Most of the infrared energy is absorbed by water vapor and carbon dioxide in the atmosphere

* Clouds reflect about 25% of insolation

* The lower the angle of insolation, the more reflection occurs

* Materials that are dark and rough are good absorbers and radiators of energy; materials that are light colored and smooth are good reflectors of energy

* Aerosols (fine particles of ice, dust, pollen, smoke, etc. in the atmosphere) scatter insolation, decreasing the amount of insolation that reaches the Earth’s surface (that’s why volcanic eruptions often make temperatures cooler)

* Radiative balance: when an object is gaining as much energy as it is losing

* The Earth is generally in radiative balance for long periods of time (centuries, etc.) but is not in radiative balance during the course of a year because temperatures vary so much during the year

[Review information on Earth’s revolution and seasons in Topic 4]

TOPIC 7: WEATHER

* Atmospheric variables: the factors that determine weather -- temperature, pressure, wind, moisture (humidity)

* Weather predictions are based on the conditions of these four variables and the probability of change

TEMPERATURE

* Temperature depends on intensity and duration of insolation (nearness to water and elevation also)

PRESSURE

* Atmospheric pressure / barometric pressure: the force of air pushing down on the Earth

* Warm air is less dense so it rises, putting less pressure on the Earth (( temp, ( pressure)

* Increase altitude (elevation) and there are fewer molecules, pressure drops (( altitude, ( pressure)

* Water vapor molecules are not as heavy as air molecules (nitrogen, oxygen), so if water vapor is added to the atmosphere, it replaces heavier molecules, so less pressure (( moisture, ( pressure)

HUMIDITY / MOISTURE

* Warm air has more energy than cold air, therefore more evaporation tends to happen in warmer air.

* As the temperature drops and air gets colder, more condensation tends to occur – it can reach the point where it is saturated (NET condensation occurs) with condensed water droplets and therefore forms dew/frost or a cloud.

* Dew point: the temperature at which air is saturated -- depends on the amount of moisture in the air

{formula on RT -- remember: dry-bulb = air temperature, subtract wet-bulb value]

* When the air temperature drops to the dew point, net condensation occurs (more condensation than evaporation), and water droplets form a cloud (clouds are made of liquid water droplets or ice crystals). If the dew point is above 0oC, water droplets form; if the dew point is 0oC or lower, ice crystals form. When the droplets or crystals get too large for the cloud to hold, they fall as precipitation.

* Relative humidity: the ratio of the amount of condensed moisture in the air compared to the amount of condensed moisture it can have at its present temperature -- expressed as a percent [ex/ 50% RH means the air has half as much moisture as it can]

* When temperature drops to dew point, RH = 100%, {see Relative Humidity and Dew Point charts on Reference Tables. Remember: dry-bulb = air temperature, and you must subtract wet-bulb value}

* For condensation to occur, there must also be a surface (called “condensation nuclei”) for the vapor to condense on -- could be pollen, bacteria, smoke, dust, salt, etc.

WIND

* Wind: the horizontal movement of air -- blows from areas of high pressure to areas of low pressure (remember letting the air out of a balloon)

AIR MASSES

* The characteristics of an air mass depend on the source region (where it forms) -- if it forms over land, it will be dry; if it forms over the Poles, it will be cool, etc. {abbreviations on RT}

* Cyclone: low pressure system, usually has warm air, winds blow into a low counterclockwise

* Anticyclone: high pressure system, usually has cool air, winds blow out of a high clockwise

FRONTS

* Front: boundary between two air masses

* Cold front: cold dense air catches up and pushes warmer air -- get violent thunderstorms, brief but heavy precipitation, then cooler temperatures (precipitation is mainly on the front line)

* Warm front: warm air catches up to cooler air -- get light, steady, long period of precipitation, then warmer temperatures, usually no storms (precipitation is mainly way ahead of front line)

* Occluded front: when a cold front catches up to a warm front -- get weather that is a combination of both types of fronts: thunderstorms with long, light, rain showers, then cooler temperatures

* Stationary front: two air masses meet but don’t move much -- weather is similar to warm front {see RT for symbols}

* Air masses generally follow a northeast track across the U.S., due to prevailing wind patterns

OROGRAPHIC / MOUNTAIN EFFECT

* Moist air blowing on the windward side of a mountain will be forced to rise thus cooling to its dew point, forming a cloud. It will release its moisture on the windward side, continue travelling over the mountain, descend on the leeward side and get warmer due to increased pressure. Therefore, the windward side (if next to water) tends to be cool and moist, the leeward side is dry and warm.

STATION MODELS {chart on RT}

* Remember that the actual pressure value is not written on the symbol -- shorten it by removing the decimal point and omitting the “9” or “10” in front. Always double check! If the value you come up with is not found on the millibar side of the Pressure Scale in Reference Tables (between 950 and 1050) it’s probably wrong

TOPIC 8: MOISTURE BUDGETS

* Water cycle: The circulation of water from the hydrosphere to atmosphere and back again

* Precipitation can:

• infiltrate the soil and become part of the groundwater

• run off into streams, lakes, oceans

• be evaporated or transpired back into the atmosphere

* Water will infiltrate the soil if the soil is permeable and unsaturated

* Porosity: the amount of space between particles

* Rounded particles have more porosity than angular or flat ones (sand is more porous than clay)

* Particles loosely packed (freshly deposited) have more porosity than ones under pressure

* Sorted particles (all same size) have more porosity than unsorted ones (sand is more porous than a mixture of sand, silt, and pebbles)

* If particles are all round and the same size, it doesn’t matter if they’re all small or all large -- porosity is the same

* Permeability: how easily water can get through spaces -- depends on how large the spaces are and if the spaces are interconnected (larger particles ( larger spaces ( more permeable)

* Capillarity: upward movement of water through the soil (capillarity is greater with smaller particles -- think of how tiny capillaries are in your body)

LOCAL WATER BUDGET

* P = precipitation

* Ep = potential evapotranspiration (how much moisture the atmosphere could take) -- depends on temperature: during warmer months, plants are more actively absorbing water and more is evaporated [if Ep values are greater in January & February then the location is in the southern hemisphere]

* Ea = actual evapotranspiration (how much moisture the atmosphere actually gets)

* St = soil storage (moisture stored in the soil for use if needed -- minimum = 0, maximum = 100)

* (St = change in storage (what gets added to or taken out of soil)

* D = deficit (when the atmosphere doesn’t get all it wants; P ( Ep; Ea ( Ep; St = 0)

* S = surplus (when the atmosphere gets what it wants, storage is full, and there’s some left over; P ( Ep; St = 100; Ea = Ep)

* Usage: when water is taken out of storage (negative (St; P ( Ep; Ea = Ep)

* Recharge: when water is added to storage (positive (St; P ( Ep; Ea = Ep)

CLIMATE

* climate depends on how much moisture an area gets and how much the atmosphere demands (P/Ep)

* generally, as latitude increases, temperature decreases

* generally, as altitude increases, temperature decreases

* water has a modifying effect on temperature because of its high specific heat -- land heats up faster so nearby water will have a cooling effect on land in hot season; land cools down faster so nearby water will have a warming effect on land in cold season

* mountains -- windward side (if near water) will have cool, wet climate; leeward side will be hot and dry (desert)

TOPIC 9: WEATHERING AND EROSION

* Weathering: the breaking down of rock material

* Erosion: moving the weathered material, taking it away

* The end products of weathering are called sediments -- boulders, cobbles, pebbles, sand, silt, clay, colloids, ions

* There are two kinds of weathering:

1. Physical -- breaking down into smaller pieces [The most common type is frost action: alternate freezing and thawing of water (this can occur only where the climate has plenty of moisture and temperatures reach freezing)]

2. Chemical -- rock is chemically changed into another substance (greatest in hot, moist climates)

EX/ oxidation (rust); carbonation (limestone dissolving to form caves); hydration (not only forms new minerals but speeds up all other processes as well)

* Generally, the rate of weathering depends on:

• climate

• surface area -- smaller particles weather faster

• mineral resistance -- some minerals weather faster than others

* Soil is a combination of sediments and organic matter (humus)

* Because of weathering and biologic activity, soil horizons (layers) develop ( topsoil, subsoil, partly weathered rock, unweathered bedrock (in order from surface down); mature soils contain all layers

* Transported soils (those that are brought by erosion from somewhere else) are more common than residual ones

* The force behind all erosional activity is gravity (causes water to flow, winds to blow, etc.)

* The primary agent / medium for erosion is running water

* Particles carried by water tend to get rounded, smoothed, and sorted by size

* Particles carried by wind tend to get somewhat rounded and “frosted” and sorted by size

* Particles carried by glaciers tend to get scratched and polished, and often occur in unsorted piles or hills

* Particles carried by gravity alone (ex/ landslide) tend to be angular, fragmented, and unsorted

EROSION BY WATER

* Velocity of a stream can be increased by increasing the stream discharge (kind of like volume) and/or increasing the slope of the streambed. The faster the velocity, the larger size particle it can carry {see RT}

* Streams carry material dissolved in solution (ions, colloids); in suspension (clay, silt); and by rolling or bouncing (sand, pebbles) -- all particles move slower than the water carrying them

* Young streams tend to have a V-shape valley and steep gradients; old age streams tend to have a (-shape valley with many meanders and/or ox-bow lakes; glaciers cut V-shape valleys into U-shape ones

* When humans intervene on nature, for example, by removing vegetation, the rate of erosion generally increases

TOPIC 10: DEPOSITION

* Deposition is the dropping off of eroded material

* Deposition is affected by particle shape, size, and density (round, large, dense ones drop first) and velocity of the agent carrying them

* If deposition occurs in quiet water, horizontal layers develop, with flatter, lighter, and smaller particles on top

EROSIONAL-DEPOSITIONAL SYSTEM

* Where stream gains velocity, (ex/ outside of curve, down a steep slope) erosion is dominant, kinetic energy is high

* Where stream loses velocity (ex/ gentle slopes, inside of curve, at end of stream) deposition is dominant, kinetic energy is low [the whole system loses energy]

* Where erosion and deposition are equal (ex/ middle of a curve), it is a state of dynamic equilibrium

TOPIC 11: ROCKS AND MINERALS

* All rocks are made of minerals

* There are only a few minerals that make up the majority of rocks on the Earth

* Minerals are identified by their chemical and physical properties:

• color -- not very useful since impurities can change color, except in some cases, such as sulfur being a

rare color

• streak -- the true color of a mineral -- not very useful, but more reliable than color; determined by rubbing

the mineral against a porcelain plate

• luster -- the way a mineral reflects light; generally classified as either metallic or nonmetallic; can

sometimes be useful

• cleavage -- breaking along planes of weakness; seen as parallel flat surfaces on the mineral; very

useful

• hardness -- mineral’s resistance to being scratched, determined by comparing with other substances of

known hardness; very useful

• specific gravity / density -- how “heavy” a mineral is; can be very useful

{See RT for chart on mineral characteristics}

* Most rock-forming minerals contain silicon and oxygen (quartz is only silicon and oxygen) in the form of a structural unit called a tetrahedron (looks like a pyramid)

* The different chemical and physical properties among silicate minerals are due to the internal structure, or arrangement, of atoms (how the tetrahedra are connected)

ROCK FORMATION

* Rocks are classified into three types [igneous, sedimentary, metamorphic] based on how they form

* Sedimentary rocks are formed from sediments -- particles transported by water -- in three ways:

1. Compaction and Cementation of deposited rock fragments -- known as “clastic” rocks; distinguished from one another by the size of particles in the rock

2. Chemical processes -- water becomes saturated with ions and chemicals precipitate out of solution to the bottom and form a rock called an evaporite

3. Organic or Biologic processes -- either made of shells from marine organisms, or coal which is formed from the compaction of decayed organisms

* Sedimentary rocks are usually “dirty” in appearance, or made of only one mineral, or contain fossils

* Sedimentary rocks are found as a thin layer covering much of the Earth’s surface

* Igneous rocks are formed from the solidification (hardening) of melted material [called magma below the Earth’s surface; lava above the Earth’s surface]

* Cooling of magma causes the minerals to crystallize, become glassy in appearance with definite structure

* The size of the crystals depends on how long the rock cools -- if it’s deep underground, it will cool very slowly creating large crystals and a coarse texture; if it cools at or near the surface, it will cool quickly and crystals will be small with a fine texture; if it cools high in the air or under water, it cools so rapidly that crystals don’t have time to form and it will have a glassy texture

* Igneous rocks usually have visible round crystals and are found deep under ground and near volcanoes & mid-ocean ridges

* Metamorphic rocks form from the recrystallization of unmelted rocks under high temperature and pressure

* Contact metamorphic rocks are those that metamorphose because of contact with hot magma

* Regional metamorphic rocks form from rocks under high pressure, like in mountain building, and tend to have bands or layers of minerals, called foliation, due to increased pressure

* Metamorphic rocks usually exhibit banding/layering of minerals (which can be distorted or folded) and occur near igneous rocks and deep inside mountains [if metamorphic rocks are found on the surface, it is an indication that a lot of erosion has occurred]

* Fossils are most often found in sedimentary rocks (heat and pressure destroys fossils in nonsedimentary rocks)

{several charts dealing with rocks are in RT.....including the one on the rock cycle that basically tells you how each rock forms}

TOPIC 12: THE DYNAMIC CRUST

* Evidence to support minor crustal changes include:

1. deformed sedimentary rock layers by tilting, folding, or faulting (because sedimentary rocks form in horizontal layers)

2. displaced fossils -- marine fossils found on mountaintops

3. changes in bench mark elevations

* Evidence of major crustal changes include:

1. zones of crustal activity -- earthquakes, volcanoes, and geosynclines occur in specific belts around the Earth [ a geosyncline is an area where sediments accumulate in a shallow basin, and their weight causes it to sink, giving more room on top for more sediments -- this “balancing” is an example of isostasy]

2. raised beaches -- beaches can sometimes have a terraced appearance which suggests uplifting of the crust

3. ocean-floor spreading -- the ocean floor is spreading out from mid-ocean ridges where magma comes up and forms new ocean floor (the age of ocean rock increases as you move away from the ridge)

4. reversal of magnetic polarity -- crystals of magnetic minerals align themselves with the Earth’s magnetic field and get locked in place when magma hardens, preserving a record of the Earth’s magnetic field and showing that it has reversed itself many times throughout history and supporting the concept of ocean-floor spreading

5. continental drift -- the fact that the outlines of the continents appear to fit together like a jigsaw puzzle and that rocks, fossils,and minerals can be correlated (matched) on different continents provide evidence for them once being a large landmass

EARTHQUAKES

* When an earthquake occurs, seismic waves are generated from the focus (point of origin) of the earthquake and are registered on instruments called seismographs

* Types of seismic waves include compressional/primary waves (P-waves) and shear/secondary waves (S-waves)

* P-waves travel faster than S-waves (so they are the first to arrive at a seismic station) and can travel through any medium -- solid, liquid, or gas -- but travel faster in more dense material; S-waves travel through only solids

* The epicenter is the point of the Earth’s surface directly above the focus of an earthquake

* The location of the epicenter can be determined using the seismic wave travel time graph {in RT} and the timed recordings from three seismic stations (the longer time period between arrival of P-waves and S-waves, the farther away the epicenter)

EARTH’S CRUST AND INTERIOR

* The fact that S-waves are not received by all seismic stations suggests that there is a part of the Earth’s interior that is liquid

* The four major Earth zones include a solid crust, solid mantle (although parts on the verge of melting, making it act like plastic), liquid outer core, and solid inner core of nickel and iron {see RT}

* Continental crust is composed of less dense granite and is much thicker than the oceanic crust made of basalt

* Density, pressure, and temperature increase with increased depth into Earth’s interior

PLATE TECTONICS

* Plate tectonics is the theory that the Earth’s crust is made of a number of solid pieces, called plates, that move. Where plates move apart, magma flows up and new crust is formed (ex/ mid-ocean ridges). Where plates collide, the overriding plate may crumble up to form mountains while the subducting plate plunges down and is melted (ex/ a trench)

* Shallow-focused earthquakes (with origins near the surface) occur where plates are moving apart; deep-focused earthquakes occur where plates are colliding

* Convection cells within the mantle may be part of the mechanism which causes the plates to move

TOPIC 13: INTERPRETING GEOLOGIC HISTORY

* Relative age / relative dating: determining the sequence of events -- which is older, what happened first, etc.

* The principle of superposition states that unless overturning has occurred, the oldest sedimentary rock layer is on the bottom

* Igneous intrusions are younger than the rock through which they cut

* Faults (cracks in rock where movement occurs), joints (immovable cracks) and folds (bends in rock layers) are younger than the rocks they are found in

* Unconformity: a “gap” in the rock record; usually seen as a buried erosional surface (suggests that something is missing)

* Correlation: the process of determining that rock layers or geologic events in two separate areas are the same

* Correlation techniques include:

1. “walking the outcrop” -- literally walking along rock layers from one location to another to see if they are the same (this can only be done where short distances are involved)

2. similarity of rocks -- matched on the basis of similarity in appearance, color, and composition

3. index fossils -- matching the fossils found in sedimentary rocks in different areas. Index fossils are special because they are evidence of organisms that lived in a specific (short) time period but in many areas

4. volcanic time markers -- volcanic ash is quickly deposited over a large area and serves as reference point in geologic time

* Geologic time scale: a scale of time that serves as a reference for correlating geologic events throughout Earth’s history {in RT}

* The geologic record shows that for most of the Earth’s history there was very little life (called Precambrian time); that most of the lifeforms that have existed have become extinct; that simpler organisms arose first and became more complex with time, and that man’s existence on Earth is extremely short in comparison to Earth’s history (0.04% of geologic time)

* Absolute age / absolute dating: assigning a definite age (may or may not be accurate) to a rock or event

* The most accurate method for determining absolute age is through radioactive dating

* Radioactive decay is the natural breakdown in the nucleus of unstable atoms. By measuring the amount of radioactive isotope (unstable), compared to the amount of decay product (stable), the absolute age can be determined.

* The rate of radioactive decay is unaffected by temperature or pressure and is predictable

* Half-life: the time it takes for half of a radioactive sample to decay into a stable form {half-lives of some isotopes in RT}

* The original amount of radioactive material is 100% ( after one half-life: 50%; ( two half-lives: 25%; ( three half-lives: 12.5%; and so on, always half as much as the previous one

* Carbon-14 is used to date specimens of organic origin (once living) and an assumed age of less than 50-60,000 years because of its relatively short half-life

TOPIC 14: LANDSCAPE DEVELOPMENT

* Three major types of landscapes:

1. mountain: area of high elevation with possibly steep gradients, distorted bedrock with signs of folding, faulting, or volcanism

2. plateau: area of high elevation but with horizontal (sedimentary) bedrock, possibly steep slopes because of many valleys cut by streams and/or glaciers

3. plain: low elevation with level surface and horizontal (sedimentary) bedrock

{see Reference Tables for Landscape Regions of NYS}

* Landscape boundaries are usually well defined, resulting from changes in rock structure: mountain edges, fault lines, ridges, cliffs, etc.

* Uplifting / Constructional Forces are those that originate within the Earth’s lithosphere and work to form new rock or raise the land. EX/ volcanism, earthquakes, folding. The source of energy for these processes is radioactive decay within the Earth

* Leveling / Destructional Forces are forces that operate at or near Earth’s surface and work to level or lower the surface. EX/ weathering, erosion, deposition. The source of energy for these processes is gravity.

* If uplifting forces are dominant in a region, the area will be rising overall. If leveling forces are dominant, the elevation will be decreasing. If both forces are acting equally, the area is in dynamic equilibrium and no change in elevation will take place.

* In arid (dry) climates, there is little vegetation to hold soil in place causing a rapid removal of sediments that results in steep slopes with sharp and angular landscape features (ex/ the Grand Canyon)

* In humid (moist) climates with abundant vegetation, soils are thick and the landscape has rounder and smoother surfaces.

* Glaciated landscapes tend to have U-shaped valleys, many lakes, hills of unsorted sediments, and scratched and polished bedrock

* Stream drainage patterns are reflective of the landscape and can be determined by looking at contour lines

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