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EARTH SCIENCE MID-TERM REVIEW
CONTENTS
1) Change in the Environment
Slides 1 - 10
2) Measuring Earth
Slides 10 - 35
3) Weathering Slides 36 - 45
4) Erosion and Deposition
Slides 46 - 80
5) Rocks and Minerals
Slides 81 - 100
6) Plate Tectonics
Slides 101 - 118
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CHANGE IN THE ENVIRONMENT
Observation - is done with the five senses see,
hear taste touch, smell
Inference is an interpretation based on
observation, it explains what is being observed
Instrument extends the senses
Prediction an inference about something that
hasnt happened yet
Classification grouping objects or observations
according to similar properties
Measurement comparison with a known
standard Interface- boundary between two things
with different characteristics
3
PERCENT ERROR
(Percent Deviation From Accepted Value)

• The formula is in the ESRT use it!!! All you
  have to do is determine which is the
  measured value and which is the accepted or
  actual value, plug in the values and run the
  equation.

DONT FORGET TO MULTIPLY BY 100!
Percent Error Difference between measured and
accepted
X 100
Accepted

• Many students get the percent error questions
  wrong, I think because it is too easy! Take your
  time and dont make silly mistakes because its
  too easy

4
DENSITY

• Density is how concentrated, or tightly packed
  the molecules are in a substance.

• The formula in the ESRT is
• Remember the DMV triangle!

__Mass__
Density
Volume

• You must be able to generate a formula for
  calculating Volume when Mass and Density are
  known, and for Mass when Volume and Density are
  known

• If you start with made up values in the DM/V
  formula, then you can re-arrange those values to
  make true equations for Volume and Mass

8
THEN
OR
4
8
4 x 2
2
M
V
D 4, M 8, V 2
M D x V
D
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DENSITY FROM A GRAPH OF M VS. V

• You can determine density from a graph like this
  by choosing any mass value, then find the volume
  that corresponds to that mass value and plug it
  into the DM/V equation.
• The most dense material is material A. It has the
  steepest slope.
• So, for example, C will sink in D, but float in
  A or B.

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Density is a property of a substance, unless

• If you have a giant boulder with a density of 5
  g/cm3, and you break off a chip, it will have a
  density of 5g/cm3.
• We say density is a property of a substance. In
  this example, the volume would change, but the
  mass would change proportionally, causing density
  to remain the same.

• BUT, if you change the temperature or pressure
  on the substance, density changes.
• As temperature , volume , density
• So the hot air balloon floats!
• As pressure , volume , density
• So,an ice ball hurts more than a snowball!

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DENSITY OF WATER

• Water has a density of 1 g/cm3 it is the
  standard.
• However, water has an unusual property.
• Most materials are densest in the solid phase.

• Water is densest at 40C
• Since water freezes at 00C, it is liquid at 40C!
• Water is at its densest when it is in the
  liquid state

• Thus, ice (solid water) floats. The most dense
  water sinks to the bottom, providing a safe
  environment for aquatic life

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CYCLIC CHANGE

• Cyclic change repeats a pattern at definite time
  intervals.
• Notice that the height of the peaks is not
  consistent, just the timing of them.
• Cyclic change is predictable.

Try This
9
RATE OF CHANGE

• An important equation that often trips students
  up is rate of change. Be able to calculate it
  with raw data, like this

• OR, with a graph, like this

10
LAW OF CONSERVATION OF ENERGY

• All change involves a flow of energy from one
  part of the environment to another.
• The flow of energy occurs across an interface
  (boundary).
• Equilibrium is a balance between forces, and
  dynamic equilibrium is a balance between changes.
  
• For example, the water flowing into the sink
  would equal the water flowing out of the sink
  there is change, but it is balanced.
• Pollution can be described several ways, but one
  definition is when the natural balance
  (equilibrium) of the environment is disrupted.
  Pollution can be natural, or man-made.

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Mapping the Earth

• In this unit we will measure Earth several
  different ways

• First we will look at earths shape

• Is its shape round or not
  so round?

• Is it smooth or rough?

• Then we will look at earths size

• How would you measure it?

• Next we will learn how the whole earth is mapped
  using latitude and longitude.

• Finally, we will use topographic maps to see how
  small areas of earth are mapped like Delmar!
  Click here to see

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EVIDENCE FOR EARTHS SPHERICAL SHAPE

• We know that Earth is round because

• Ships appear to sink as they approach the
  horizon
• Other celestial objects are round.
• Now we can see earth from space, and photograph
  it!

• BUT, the most important proof that Earth is
  round is the fact that the altitude of Polaris
  increases as you move toward the North pole, or
  decreases as you move toward the equator. This
  would not happen on a flat Earth. A quicker way
  to say it is the altitude of Polaris changes
  directly with latitude.

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EARTHS SHAPE

• Of course, Earth is not perfectly spherical

• What is the exact shape of the Earth?

NOT THIS EITHER BUT CLOSE!
NOT THIS!
NOT THIS!
It is fatter around the equator
This shape is called an oblate spheroid
Define this sphere, or ball
All the diameters (or radii) are the same they
are all equal!
Earth looks more like this!
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Oblate Sphere

• This is a more realistic view of Earth

• Its not really as oblate or oval as I drew
  it on the previous slide

• But its still an oblate sphere can you tell
  by looking at the dimensions?

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SMOOTHNESS

• Like earth, this basketball looks perfectly
  round, even though it is slightly fat around the
  middle

• Also like Earth, it looks very smooth but is
  it? Its not perfectly smooth, is it?

• How would you quantify the smoothness of this
  ball?

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EARTHS SPHERES

• The three spheres are lithosphere, hydrosphere,
  and atmosphere in order of decreasing density!
• There are other spheres, for example the
  asthenosphere, which is the plasticy layer that
  lubricates the movement of lithospheric plates in
  tectonic theory.
• The atmosphere is subdivide into spheres, each
  having distinct properties

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• Notice that altitude here means height above sea
  level, and altitude of Polaris means an entirely
  different thing!

• Notice that pressure decreases with altitude, and
  so does water vapor. In fact, there is no water
  vapor above the troposhere.
• Temperature does not have such a predictable
  trend. The temperature changes caused by the
  different gases that make up the layers. The
  gases are arranged by density. Be able to state
  temperature at any point, or set of points.

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Where are we?

• So now we know that Earth is not perfectly round
  or smooth, and is quite large

• How would you keep track of where you are on
  such a big planet? At first, people used stars

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USING STARS TO NAVIGATE

• Early sailors used a device like this to know
  where they were on this huge Earth

• The device was used to measure the angle between
  a star, and the horizon. This angle is the
  altitude of the star.

• By far the most important star was Polaris, or
  the North star, because the altitude of Polaris
  told you how far North of the equator you were
  (latitude!)

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ALTITUDE OF POLARIS EQUALS LATITUDE
Activity To find out what latitude you are at
using the same method as the Vikings, you need
two meter sticks, a nut and bolt, a level, and a
protractor. Fasten the two sticks together at one
end using the bolt. Use a level to line up one
stick parallel to the Earth. Sight along the
other stick to Polaris and tighten the nut on the
bolt. Measure the angle of elevation, Angle 1.
This is your latitude.
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LATITUDE IS

• Angular distance north or south of the equator

• Parallel lines, equator is zero degrees, north
  pole is 90 degrees north

EQUAL TO ALTITUDE OF POLARIS!!!
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LONGITUDE IS.

• Angular distance east or west of the prime
  meridian

• Longitude lines are not parallel, and get closer
  together as you move towards the poles

• NOT determined by the location of Polaris, but
  another star THE SUN!

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Longitude lines run up and down (North South)
and determine your location east or west of the
prime meridian
Latitude lines run east/west and determine your
location north, or south of the equator
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LONGITUDE AND TIME

• Since longitude is determined by the position of
  the Sun, it can be used to determine time

• If you know time at one location, you can say
  that it is one hour earlier for every 15 degrees
  to the west

• You can also say that it is 1 hr. later for very
  15 degrees to the east

• Another way The occurrence of any time moves
  west at 15 degrees per hour

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FIELD MAPS

• A field is an area that has some measurable
  value, of something, at every point.
• Fields can be large, for example the U.S. is a
  field in which temperature can be measured at
  every point, and mapped so that people can see
  the trend.
• Or, a field can be small, for example this room,
  where we might measure the light level at every
  point.
• Isolines connect points of equal field value on
  a map.
• There are scalar fields, where only magnitude is
  measured
• And vector fields where magnitude and direction
  are measured. An example of a vector field is
  wind.

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TOPOGRAPHIC MAPS

• Field maps that show elevation above sea level
  with contour lines.

• Be able to determine contour interval, distance,
  direction, and gradient.

• Recognize natural and man-made features like
  roads and trails

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DIRECTION OF STREAM FLOW

• You must be able to determine the direction of
  stream flow by knowing that the Vs point
  upstream

• These tributaries flow into the Genesee river
  in western New York, which flows NORTH!

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TOPOGRAPHIC PROFILES

• To determine what the actual land shape would be

1) First lay a strip of paper along the line that
you wish to turn into a profile
2) Next, make a mark everywhere that a contour
line touches your paper. Record the elevation of
each mark.
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COMPLETING THE PROFILE

• Establish the values that you need on the Y-axis

• Then use the strip of paper as your X-axis

• Plot the elevation values on the Y-axis, connect
  the dots, and you are done!

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WEATHERING

• Weathering is breaking rocks down into smaller
  pieces by exposing them to the atmosphere and the
  hydrosphere.
• Those pieces are called sediments, colloids, and
  ions.
• Sediments are of many different sizes, see

• Colloids are smaller than clay, and stay
  suspended indefinitely, even in water that isnt
  moving.
• Ions are charged particles that become dissolved
  in water they are part of the water. Thus, they
  move as fast as the water.

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FACTORS THAT EFFECT WEATHERING RATE

• Rate means how fast something happens
• Rocks that are made up of soft minerals
  will weather slower than
• Increased surface area causes rocks to weather
  faster, because more area is exposed to
  hydrosphere and atmosphere.

hard minerals
soft minerals

• In this diagram the particle size gets smaller,
  causing greater surface area!

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CLIMATE AND WEATHERING

• There are two main types of weathering

• Physical weathering breaks the rock down with no
  change in chemical composition
• Chemical weathering causes changes in the rocks
  chemical composition, which then causes it to
  fall apart

• Chemical weathering is accelerated by warm
  temperatures and water
• Physical weathering is accelerated by cold
  temperatures and water

• Be able to read this graph it
  summarizes the way climate affects weathering

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EXAMPLES OF PHYSICAL WEATHERING

1. Frost action is most important in N.Y.S. ! It
   occurs when water gets in a small crack in a
   rock, freezes, expands, and makes the crack
   larger. The next night the process continues,
   until the rock falls apart. Is most effective in
   climates with alternate freeze / thaw periods.

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OTHER EXAMPLES OF PHYSICAL WEATHERING
2. Roots of large plants, or of small plants,
like grasses, can wedge into the rock and break
it apart physically.

• Notice the two roots that are splitting this
  large rock apart

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ROCK ABRASION IS PHYSICAL WEATHERING
3) As rocks are being carried downstream
(erosion!), they are also being weathered
physically as they bang into each other.
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CHEMICAL WEATHERING

• In chemical weathering, rocks are exposed to
  something in the hydrosphere and/or atmosphere
  that changes their chemical composition. This
  change makes the rock weaker, and it begins to
  fall apart.

• This rock is rusting. Notice the orange
  color.Rust is one kind of chemical weathering

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TYPES OF CHEMICAL WEATHERING

• We have already mentioned rust. Rust happens
  when oxygen combines with the iron in rocks to
  make iron oxide (rust!).

We say that the iron is oxidized. Iron is strong,
but rust is not. The reaction looks like this
Fe O2 Fe2O3
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ANOTHER TYPE OF CHEMICAL WEATHERING

• CO2 H2O H2CO3
• Limestone is particularly susceptible to
  carbonic acid, which is present in dilute
  concentration in every stream.
• When streams flow through limestone formations
  for millions of years, they eat away huge amounts
  of limestone, creating a cave.

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TWO MORE TYPES OF CHEMICAL WEATHERING

• Hydrolysis is when rocks are exposed to water.
  Obviously this happens a lot! Some of the
  minerals in the rock are actually dissolved by
  water. When these minerals are removed, the rest
  of the rock falls apart.

• Acid rain happens when industrial and exhaust
  emissions , mostly sulfuric acid, combine with
  rain water to make a weak acid. Acid rain has
  devastating effects on rocks, including those in
  this statue

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EROSION

• So, weathering is breaking rocks down into
  smaller pieces by either chemical or physical
  means.

• Erosion is moving those smaller pieces from one
  place to another

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FIVE AGENTS OF EROSION
We will cover five agents of erosion. Each one
leaves its mark on the sediments that it moves.

• Streams round the sediments, and sort them by
  size.
• Glaciers scratch the sediments and leaves them
  unsorted
• Wind leaves the sediment pitted or frosted.
• Mass Wasting leaves the sediment sharp.
• Waves sort sediments but dont leave
  characteristic marks

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ROUNDING AND SORTING

• This is what is meant on the previous slide by
  rounding and sorting

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GRAVITY DRIVES ALL EROSION

• GRAVITY is the underlying force that all agents
  of erosion use to move sediment around.

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STREAM EROSION / DEPOSITION

• Streams are the most important agent of erosion
  because they move far more sediment on Earth than
  the other four agents combined.

• The portion of the Earths surface that is
  drained by a stream is its watershed.
• When stream B flows into stream A, we say that
  stream B is a tributary.

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HOW STREAMS MOVE SEDIMENT

• Sediments are of several sizes. Some are the
  size of molecules, and can become dissolved in
  the water. We say those sediments are in
  solution.
• Silt clay are in suspension, making the water
  look muddy

• Larger sediments bounce along the bottom this
  is called saltation.

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WATER SPEED AND CARRYING CAPACITY

• What size sediment a stream can carry in
  suspension is determined by the speed, or
  velocity of the stream.
• When a stream slows down, it deposits the
  largest sediment first.

• This is how streams sort sediments by size.
• For example, a stream that is moving at 200
  cm/sec can carry cobbles, and everything smaller
  than cobbles. But as soon as it slows to 180
  cm/sec, the cobbles are deposited.

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WHAT WOULD MAKE A STREAM SLOW DOWN?

• There are two things that make a stream slow
  down.

• One of waters properties is that it sticks
  together. This is called adhesion. So, the water
  going around the inside sticks with the water
  going around the outside. That water has to go
  faster, and the water on the inside goes slower.
• The end result is a deposit of sediment on the
  inside, and erosion (moving away) of sediment on
  the outside.

48
HOW THIS EROSIONAL - DEPOSITIONAL SYSTEM WOULD
LOOK

• The previous birds eye view diagram would look
  like this in reality. Notice the cut bank at
  point C, where the water is moving fast because
  it is on the outside of a curve. It is moving
  faster than at point D because it has further to
  go.

• Also notice the deposit at point D where the
  water is moving slowly because it is on the
  inside of a curve.

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THE SECOND THING THAT SLOWS A STREAM

• When a stream reaches its mouth, which is
  when it flows into a lake or ocean, its velocity
  is slowed gradually.

• This results in deposition of large sediment
  near shore, and progressively smaller sediment
  further out. This sorting of deposited sediment
  takes the shape of a Greek letter D (delta).

50
WHAT A DELTA LOOKS LIKE

• As the deposits build up at the mouth of the
  river, they begin to form a triangle shape, which
  is the shape of the Greek letter delta (D).
• The deltas at the mouth of large rivers, like
  the Mississippi or Nile, are huge deposits that
  must be dredged out regularly so that ships can
  get through.

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HORIZONTAL SORTING

• When a stream enters a still body of water, it
  slows down gradually. Remember that stream
  velocity determines what size sediment the stream
  can carry.

• In the delta, the largest sediments are closest
  to shore, and they get progressively smaller as
  you move away from shore.

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GRADED BEDDING

• What you see below is called graded bedding. It
  is what we saw when we dropped several sizes of
  sediment into still water

• This can happen in streams in two different
  ways.
• One way is for a flooding stream to carry all
  sediment sizes to a lake or ocean, and deposit
  them all at once.

• Another cause of graded bedding is the seasonal
  fluctuation in stream velocity. This stream may
  be moving fast enough to carry the pebbles in
  Spring, but it deposits sand in June, silt in
  July, and clay in August when the stream is dry
  and slow.

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STREAM LIFE CYCLE

• Like a living thing, streams go through a life
  cycle.
• The stages are called youth, maturity, and old
  age.
• Think of streams as a leveling force. This
  means that, as tectonic forces raise the Earths
  crust slowly by building mountains and volcanoes,
  streams are slowly lowering these features by
  eroding them away.

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YOUTHFUL STREAMS

• When a stream is young, it is just getting
  started at its task of leveling a mountain.
• For thousands of years it is down-cutting the
  mountain.
• The cutting tools that the stream uses are the
  sand and pebbles that it carries. These cut a V
  shaped valley!
• Because the mountain has not been leveled yet,
  the stream has a steep gradient, and so it has
  high velocity (goes fast!). It also has a pretty
  straight course (straight downhill!).

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A STREAM AT THE YOUTH STAGE

• This is a typical stream at the youth stage of
  its life cycle.
• Notice the V shaped valley. Also, the course
  of the stream is straight.
• Also notice that the mountain has not been
  leveled very much yet.
• This stream has a steep gradient, and a high
  velocity notice the rapids.

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A MATURE STREAM

• This stream has significantly leveled a
  mountain. The sides of the stream valley have
  been eroded by tributaries. This is called
  lateral erosion, meaning sideways erosion.

• The stream deposits the mountain, in sediment
  form, on the sides of its bank this is called
  a floodplain.

• There are natural levees, a low gradient, and
  the stream has started to meander.

57
A STREAM AT THE OLD AGE STAGE

• Remember when we talked about how a stream
  erodes on the outside curves, and deposits on the
  inside curves?
• If the stream keeps doing this for thousands of
  years, it will make its curves turn harder and
  harder.
• The end result is meanders like you see here.
  Eventually, when the stream floods, it cant make
  those hard turns, and it shoots straight across,
  cutting off a section that becomes an oxbow
  lake.

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GLACIERS AS AN AGENT OF EROSION

• There are two types of glaciers. The first are
  called alpine, or valley glaciers. They form in
  places where the amount of snow that melts in
  summer is less than the amount of snow that falls
  in winter. The end result is an annual
  accumulation of snow.

• When the snow has accumulated to great depths,
  gravity pulls down on it,turning it into ice.
• Then gravity makes it spread out in all
  directions it appears to flow.

• This graph shows the places on earth where
  winter accumulation can exceed summer melting.
  Notice that glaciers can exist at the equator, at
  elevations above 5200 meters.

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AN ALPINE, OR VALLEY GLACIER

• The previous slide indicated that at the poles,
  alpine glaciers can exist at low elevations. This
  one ends at sea level.

• As the glacier flows along, it grinds up the
  mountain and carries (erodes!) the sediment
  downhill.
• You can see the sediment in the ice here. These
  are called lateral moraines, meaning side
  moraines.

60
HOW GLACIERS FLOW

• Like a stream, a glacier has friction with the
  sides and bottom of its valley.
• This causes it to be slowed on the sides, and
  fastest in the middle.

• In diagram A, flags were set in a straight line.
• As the glacier flowed from right to left, the
  flags in diagram B indicate faster movement in
  the middle.

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ALPINE GLACIAL FEATURES

• This diagram shows the rounded
  features that result from stream erosion.

• This diagram shows the angular features that
  alpine glaciers carve.

• This diagram shows how a glacially carved
  mountain looks when climate change causes the
  alpine glacier to melt away. Notice especially
  the U shaped valley that typifies glacial valleys.

62
CONTINENTAL GLACIATION

• Occasionally, Earth goes through a period of
  colder climate. The last time this happened, 1
  million years ago, about half of the Earth got
  more snow in winter than could melt in summer.

• This annual accumulation built up to great
  depths. Eventually, all of Canada was a glacier
  that stood two miles high above the land!

• This continental glacier spread out in all
  directions. It overran New York State,causing
  many of the features we see today.
• 10,000 years ago the climate warmed, and the
  glacier melted back. The next slide shows some of
  the features left behind.

63

• Try to imagine the true scale of these features.
  If the ice is 1-2 miles high, then these other
  features are large also.

• Drumlins are uniquely shaped hills. They have a
  steep side and a not so steep side. They look
  whales swimming North.

• A terminal moraine is a pile of unsorted glacial
  till, dumped where the

• Round Lake is a kettle lake

glacier stopped advancing. Long Island is a
terminal moraine.

• Glacial till is scratched and unsorted

64
GLACIAL STRIATIONS

• These scratches in the bedrock were caused by a
  glacier dragging rocks across it.
• The scratches are called striations. They tell
  us what direction the glacier moved in.
• Scratched and grooved bedrock, unsorted and
  scratched deposits are characteristic of glaciers

65
TWO QUESTIONS

• Remember the lab where we dropped the beads and
  timed them? We found that some beads fall fast (
  and have a small settling time). Other beads fell
  slowly, and had a long

settling time. We found that

1. Large beads fall faster than small ones.
2. Dense beads fall faster
3. Round beads fall faster than flattened beads.

• Dont get mixed up! Remember, a high settling
  speed causes a low settling time

66
WIND AS AN AGENT OF EROSION

• Wind can move (erode!) sediments only if they
  are small, and dry.
• Wind usually blows the clay and silt completely
  away, and then blows sand around for thousands of
  years.

• Because it cant lift the sand up very high, the
  bottoms of rocks are eroded more than the tops.
• Desert landscapes often have these mushroom
  rocks.

67
VENTIFACTS AND DESERT PAVEMENT

• Two other common features of hot, dry landscapes
  with wind erosion are shown here.
• The large rock is pitted, or frosted because
  it has been bombarded by sand grains for a long
  time. Remember, sand is quartz very hard!
• The ground around the large rock is called
  desert pavement because all the sand, silt, and
  clay has been removed, leaving a hard pebble
  pavement.

68
WIND MOVES THE SAND AROUND

• Places with a lot of wind erosion have sand
  dunes. They can be very beautiful, as you see
  here.
• The dunes resemble snow drifts here in the
  Northeast.
• It is great fun to run up to the top of them and
  jump off the slip face. You fly about twenty
  feet, and you dont get hurt!

• Dunes migrate downwind because the wind keeps
  moving the sand.

69
HOW WATER WAVES MOVE AND WHY THEY BREAK ON THE
BEACH

• The particles in a wave move in circular paths,
  as shown here
• As the wave approaches a beach, the shallow
  water pushes the circulating particles up - the
  wave gets larger

• Next, the bottom of the wave slows down, due to
  friction, but the top keeps going the same speed
  the wave falls forward this is a breaker.

70
WAVE REFRACTION STRAIGHTENS COASTLINES

• As waves approach a rocky headland they turn
  and focus their energy on anything that is
  jutting out. This has the effect of straightening
  the coastline out.

• This happens because the side of the wave that
  is closest to shore is slowed by friction. The
  edge that is farther from shore stays the same
  speed and catches up.

71
LONGSHORE CURRENT

• The longshore current is an important aspect of
  wave erosion because it can cause problems for
  people who live and work at the shore.

• The water in a wave cannot get away from the
  beach because another wave is behind it. The
  water flows along the shore until it finds a way
  out. This flow down the beach is the longshore
  current. It transports sand, sometimes to places
  that people dont want it.

72
LONGSHORE CURRENT QUESTIONS

• People install groins, or jetties to block the
  longshore movement of sand.
• The breakwater here will prevent the long-

shore current from taking any sand away from the
beach behind it.
73
WEATHERING, EROSION AND SOIL

• When rocks are weathered into sediment, and the
  sediment is eroded to a new location, and
  deposited there, two things can happen to the
  sediment that has been deposited.
• The first is that organic material can be added
  to the sediment to make topsoil. This organic
  material takes much

time to build up. It comes from the life, and
death, of countless organisms
74
THE SECOND THING THAT CAN HAPPEN TO SEDIMENT

• When sediments accumulate in thick layers, the
  sediment at the bottom is buried under many tons
  of other sediment and is thus compacted
  tremendously.

• This squeezes the water out of the sediment.
• Then, natural cements in the water are left
  behind to glue the sediment into sed. rock.

75
MINERALS

• Minerals are solid, inorganic, crystalline,
  natural substances with definite chemical and
  physical properties.
• We identify minerals by determining their
  streak, hardness, and cleavage.
• For the Regents you only need to know if luster
  is metallic, or non-metallic.
• Be able to find mineral properties on the last
  page of the ESRT.

ROCKS ARE
MADE OF
MINERALS
!!!!
76
INTERNAL ARRANGEMENT OF THE ATOMS

• The characteristic physical and chemical
  properties that we referred to in the definition
  of a mineral, are determined by how the atoms are
  arranged in it.

This arrangement of atoms is called a
tetrahedron. It has four sides. It is made up of
one silicon (red), surrounded by four oxygens
(brown, there is one hidden on the other side).

• An important group of minerals (called
  silicates) are made up of

different arrangements of this basic building
block. The arrangement determines the
properties of that particular silicate mineral.
77
THREE QUESTIONS ABOUT SILICON-OXYGEN TETRAHEDRON

• These are three regents questions about the shape
  of this important building block of silicate
  minerals.

• Can you answer them?

• Remember, it is the internal arrangement of
  molecules like these that determine the definite
  physical and chemical properties of a mineral.

78
THE ROCK CYCLE

• This graph just shows the ways that the various
  type of rocks form.
• Notice that any rock can be the source of
  sediments.
• Notice also that any rock can be metamorphosed,
  or melted to form magma.

ROCKS ARE
MADE OF
MINERALS
!!!!
79
IGNEOUS ROCKS

• Igneous rocks are rocks that cooled from a
  molten state to a solid state. The molten rock
  (magma) is a mixture of minerals.

• When the magma cools and solidifies, we say that
  igneous rocks are intergrown mineral grains.

80
ENVIRONMENT OF FORMATION

• Some igneous rocks are formed when volcanoes
  extrude molten rock it is called lava when it
  is extruded.
• These rocks cool quickly, and so they have small
  mineral grains.

• Other igneous rocks form when the magma gets
  close enough to the surface of the Earth to cool
  and harden- these are igneous intrusions
• These rocks cool slowly, and so they have large
  mineral grains.

81
OUR SIMPLIFIED CLASSIFICATION SCHEME FOR IGNEOUS
ROCKS

• This shows you the basic info contained in the
  ESRT iggy rock scheme on the next page. Notice
  that the extrusive rocks rhyolite and basalt are
  fine grained. Also, the intrusive rocks granite
  and gabbro are coarse grained.

• These are Felsic rocks

These are Mafic rocks
82
THE ESRT IGGY ROCK I.D. SCHEME
Extrusive rocks are fine grained (or glassy)
because they cooled quickly.
Intrusive rocks are coarse grained because they
cool slowly
Mafic rocks have pyroxene and olivine, but no
quartz or pink feldspar
The Felsic rocks have quartz and
and potassium (pink) feldspar, but no pyroxene or
olivine.
83

• Both of these rocks cooled quickly, because they
  were extruded from Earth by a volcano.They are
  fine grained (small mineral grains).
• The dark colored one is basalt. It is
  mafic, which means it is more dense.
  
  
  

• The light colored one is rhyolite. It is felsic,
  which means it is less dense.
• Notice the pink color of the potassium feldspar
  this mineral defines felsic iggys

84

• Both of these intrusive igneous rocks cooled
  slowly, deep within the Earth. We say that they
  are coarse grained (large mineral grains).
• The light colored one is granite.It
  is felsic ( has pink potassium feldspar, and
  aluminum less dense).

• The dark colored one is gabbro. It is
  mafic, which means that it has pyroxene and
  olivine, no pink feldspar or quartz, and is more
  dense (because it has iron and magnesium)

85
OTHER IGNEOUS ROCKS

• Both of these rocks cooled so quickly that air
  was trapped among their intergrown mineral
  crystals
• This one is pumice, it is felsic and vesicular
  (trapped air).

• This one is darker in color, so it is
  mafic. This means that it is more dense.
• It has trapped air (meaning it is vesicular),
  and is mafic, so it is scoria.

86
ONE MORE IGNEOUS ROCK

• This igneous rock cooled instantly, usually
  because the lava flowed into water. It has such
  small grains that we say that it

• has a glassy texture.
• Notice the way that it fractures like a sea
  shell. We say that it has conchoidal fracture
• You cant tell if this is mafic or felsic they
  look the same.
• This could be obsidian or basalt glass.

87
SEDIMENTARY ROCKS

• This is a more colorful version of the rock
  cycle than you have in your ESRT
• Notice that sedimentary rocks form when sediment
  is buried, compacted and cemented.
• Notice also that any of the three rocks can be
  the source of sediments

88
CLASTIC SEDIMENTARY ROCKS

• So the classification system is based on
  sediment size

• You may be expected to recognize these map
  symbols for each rock

• Clastic sed rocks are made of sediments that are
  called clasts, or fragments of other rocks, of
  these sizes

89
CHEMICALLY AND/OR ORGANICALLY FORMED SEDIMENTARY
ROCKS

• There are two subgroups here. One is the rocks
  that form when dissolved ions of calcite, halite,
  or gypsum become so concentrated in the water
  that they precipitate, or fall out of solution,
  and form rock layers.

• The second subgroup is formed from pieces of
  things once living(organic). Thus, limestone and
  coal are bioclastic, or organically formed.

90
FOSSILS ONLY OCCUR IN SEDIMENTARY ROCKS

• Fossilization requires quick burial, and
  sediment deposition does the trick

• These are all fossils!
• The only type of rock that has fossils are sed.
  rocks.

91
METAMORPHIC ROCKS

• Metamorphic rocks are changed from one rock to
  another by being exposed to extreme heat and/or
  pressure.
• There are two ways that a rock can be exposed to
  heat and/or pressure contact or regional
  metamorphism.

• Contact metamorphism occurs where rocks are in
  contact with an igneous intrusion.
• They are not melted, but they are exposed to
  extreme heat.

• Here, sandstone has been intruded. The sandstone
  that was in contact with the intrusion, but not
  melted, is now quartzite. The metamorphic rock is
  indicated by the line symbol.

92
REGIONAL METAMORPHISM

• The contact metamorphism on the previous slide
  occurred in a relatively small area.
• Regional metamorphism occurs over a larger area
  (region)

• The heat and pressure that causes metamorphism
  here is due to great friction between tectonic
  plates.

• The rock at the interface between plates that is
  not melted, is changed.
• The deeper the original rock, the greater the
  grade of metamorphism. See next slide for
  description of grade.

93
SCHEME FOR METAMORPHIC ID FROM ESRT

• This is only half of the ESRT scheme for
  metamorphic rock I.D. These are the foliated
  rocks, which means that they show layering.

• The foliated rocks are classified by grade,
  which means how heavily have they been changed.
• The deeper rocks are changed more (high grade,
  e.g. Gneiss). The shallower rocks are changed
  less, (low grade, e.g. Slate)

94
LOW GRADE METAMORPHISM

• This is slate, you can see what is meant by
  layers, or foliation.
• It is metamorphosed from shale.
• It is low grade because the shale was not buried
  very deeply when it came in contact with great
  pressure from plates rubbing together.

95
A METAMORPIC ROCK - SCHIST

• Schist is the third grade of metamorphism,
  meaning it was exposed to more heat and pressure
  than phyllite, but not as much as gneiss.
• This schist shows the shiny texture that results
  from recrystallization, forming mica crystals.

96
HIGH GRADE METAMORPHISM - GNEISS

• The highest grade of metamorphism is GNEISS it
  looks nice!!
• You see distinct banding of light and dark
  minerals

• This sample shows distortion and banding.

97
ESRT SCHEME FOR METAMORPHIC ROCK ID
Again, these map symbols may turn up in a
question.

• The non-foliated metamorphics are included now.
  Marble and quartzite show no layers(foliation).
  Like the others, they are harder and denser than
  the rocks they started out as. Quartzite forms
  from sandstone, marble from limestone.

98
TRY SOME PRACTICE QUESTIONS

• Rock A would be conglomerate
• Rock B sandstone
• Rock C is fossil limestone
• Rock D an intrusive, coarse grained igneous rock
  (Granite or Gabbro)
• Rock E Gneiss
• Rock F Breccia

99
A CLASTIC SEDIMENTARY ROCK

• This is sandstone. It is cemented grains that
  range from .2 cm - .006 cm.
• Because those grains are pieces of other rocks,
  and not dissolved chemicals, we say that it is a
  clastic, land-derived sedimentary rock.

100
ANOTHER CLASTIC SED. ROCK

• This clastic sed. rock is shale. It is made of
  sediments that are less than .0004 cm. See the
  ESRT sed rock

classification scheme for the size of the clasts
in each rock type.
101
Evidence for crustal movement

• Tilted, folded,or faulted rock strata were
  originally horizontal, and have since been moved
  by plate tectonics.

• This is faulted, and this is folded.

102
MORE EVIDENCE FOR CRUSTAL MOVEMENT

• Displaced roads and orchards are evidence that
  Earths crust has moved.

103
Earths Tectonic Plates

• Earth is made up of many different plates
• A plate is about 50 miles thick
• The plates move about as fast as your fingernails
  grow (1-3/year)

104
Tectonic Plate Boundaries

• The border between two plates is called a
  tectonic plate boundary

• Most earthquakes and volcanoes occur at plate
  boundaries
• All around the boundary of the Pacific plate
  there are a tremendous number of earthquakes and
  volcanoes.
• That is why it is called the Ring of Fire!

105
Types of Plate Boundaries

• This is page five of your reference tables
• It shows the three main types of plate boundaries
  

They are Divergent, Convergent, and Transform
Boundaries
106
Divergent Plate Boundaries

• To diverge means to move apart (or spread)
• Tectonic plates spread at mid ocean ridges
• The spreading type movement at these boundaries
  is what pushes all the other plates around

107
CONVECTION CELLS CAUSE THE SEA FLOOR PLATES TO
DIVERGE

• The divergence at the mid ocean ridge (a.k.a.
  sea floor spreading) drives all the other plates
  around

• and it is the convection cells that cause this
  divergence

108
Convergent Plate Boundaries

• To converge means to come together
• Two plates can be pushed together when the
  spreading at the mid-ocean ridge creates more
  crust and pushes earths plates around to make
  room for that crust

109
Ocean converges with continent

• This drawing shows a mid ocean ridge pushing some
  ocean plate into a continent on the right.
• The ocean plate is more dense, so it sinks under,
  or subducts, under the continental plate.Thus, we
  call this a subduction zone.
• The result is earthquakes where the plates rub
  into each other, and volcanoes slightly inland
  (labeled rising magma here).Click here.

110
Continent converges with continent

• When two continental plates collide, neither
  plate subducts, because they are the same
  density.
• The result is tremendous earthquakes and mountain
  building, like the Himalayas shown here

Click here for continental collisions!
111
Transform type plate boundaries

• At transform boundaries, the two plates dont
  converge or diverge.
• Instead, they slide sideways past each other.
• Transform boundaries are sometimes called strike
  slip faults

112
THE SAN ANDREAS FAULT IS A TRANSFORM BOUNDARY

• The san Andreas fault marks the boundary between
  the North American plate, which is moving south,
  and the Pacific plate, which is being pushed
  north. As these two huge slabs of Earth slide
  past each other, earthquakes result. Watch the
  video below for more information.
• Note that there are no volcanoes at transform
  boundaries

113
Here is a nice labeled version of the Earths
Crust w/ labeled tectonic features
114
USING P S WAVE GRAPH TO DETERMINE EPICENTER
DISTANCE Be sure you understand how to do
this!!!! If you dont go the Power Point
Earthquake Waves and read through the procedure
MEMORIZE IT
115
Remember you must have at least 3 stations to
locate and epicenter!
116
The properties of the Earths Interior ESRT pg
10!
117
Island Chain Formation over a hotspot Indicates
plate motion, can be used to calculate rate of
movement for the plate.
118
Shield volcano composite volcano (like Hawaii)
(like Mt. St. Helens) Over Hotspot Over
subduction Zone