Cumulative Quarter Review Sheet
I. Weathering
Def: The physical and chemical breakdown of rock into smaller particles called sediment
A. Physical Weathering – occurs when rocks are cracked, split, or broken into smaller
pieces (without changing chemical composition)
1. Temperature change – leads to exfoliation (peeling of top layer)
2. Frost Action- freezing and expanding of water, splitting rocks
3. Organic Activity- trees grow through cracks of rocks and split them
4. Abrasion- occurs when rocks collide into other rocks as they travel by wind or
water
B. Chemical Weathering- occurs when certain chemicals in the environment interact with
minerals that makeup a rock, breaking down or dissolving the rock
1. carbonation- when carbon dioxide from the atmosphere dissolves water droplets in
a cloud  forms carbonic acid
Ex: forms underground cave (stalactites vs. stalagmites)
2. hydration- occurs when water dissolves certain minerals in a rock
Ex: typically in moist/wet climates (Cleopatra’s needle)
3. oxidation- occurs when oxygen in the atmosphere combines with certain minerals
in a rock  forms rust.
4. Plant acids- produced bother by plants and animals and can dissolve certain
minerals in rocks.
5. Man-made acids- form when man-made gases (sulfur & nitrogen dioxides)
dissolve in the droplets of water that make up clouds. This causes  sulfuric acid
rain and nitric acid rain. (damage our ecosystem)
C. Rate of Weathering- based on temperature and precipitation
1. Temperature
Ex: warm/moist climates  chemical action is dominant
Ex: cold climates  frost action
2. Precipitation
Ex: ↑ in precipitation  ↑ in frost action
Ex: ↑ in precipitation  ↑ in chemical weathering
3. Type of rock – soft weak minerals are less weather-resistant and wear away faster,
leaving behind the harder, more weather-resistant rocks.
4. Particle size- an increase in surface area  increase in rate of weathering
II. Soil
Definition: a combination of weathered rock and organic material
A. Soil layers
1. “A-horizon”- top soil, rich in humus, fine particles, light colored
2. “B-horizon”- small amounts of humus, s-m size particles, small amount of
weathering, and dark in color
3. “C-horizon”- broken bedrock, trace amounts of humus, almost no weathering
4. Bedrock- bottom layer, no organic material, solid bedrock
III. Erosion
Definition: the transporting or movement of sediment from one place to another
A. agents of erosion- the forces or materials that transport or move sediments
1. gravity- creeping of sediments downhill (landslides, mudslides, lava flows)
2. Wind- most effective where silts, clays, and sands lie loose, dry, and unprotected.
(abrasion and deflation are two essential processes)
3. streams- the dominant form of erosion
- discharge (volume)- (as volume ↑, stream erosion ↑)
- velocity (speed)- (as velocity ↑, stream erosion ↑)
- gradient (slope) – (as gradient ↑, stream velocity ↑)
- meander (curves)- as velocity around meanders ↑, erosion on the
outside curve ↑ as well.
- particle size vs. water velocity – ESRT pg. 6
*erosion occurs on the outside of a meander
- create V-shaped valleys
4. glacier- large mass of moving ice and snow (continental vs. alpine)
- sediments become embedded in glaciers as it is transported
- create U-shaped valleys
IV. Deposition
Definition: The point where sediment is no longer being transported by an agent of erosion,
and it is dropped off and left at a new location.
A. Factors that affect deposition
1. particle size - the larger the particle, the↑ settling rate (settle faster)
- the smaller the particle, the ↓ settling rate (settle slower)
2. particle shape - the more round the particle, the ↑ settling rate
- the flatter the particle, the ↓ the settling rate
3. particle density- the more dense the particle, the ↑ the settling rate
- the less dense the particle, the ↓ the settling rate
B. Agents of deposition- the forces that deposit sediments in a new location
1. Gravity- acting alone as the agent of erosion, sediments are unsorted
2. Wind- finer than particles deposited by other agents (windward vs. leeward, sand
dunes)
3. water- in water sediments may be deposited and sorted horizontally or vertically.
*deposition occurs on the inside of a meander
Ex: horizontal  largest/densest particles near shore, finest offshore
Ex: vertical  largest/densest particles near bottom, finest near top
5. glaciers- deposited sediments are always unsorted
V. Landscapes/Drainage Systems
Definition: landforms that are related by common origin.
A. Earth’s topography is affected by tectonic forces, climate, human activity, time
1. humid- landscapes are rounded, and have plenty of soil to protect rock beneath
2. arid- sharp angular rock, bare steep slopes
B. Different Regions
1. Mountains – greatest relief, deformed rock, young rivers, v-shaped valleys
Ex: Appalachian Mountains, Tectonic Mountains (ESRT 2)
2. Plateau- moderate relief, flat tops, flat layers of sedimentary rock
Ex: Tug Hill Plateau, Allegheny Plateau
3. Plains- lowest relief, flat, horizontal rock layers, undisturbed sedimentary rock
Ex: The Hudson-Mohawk Lowlands, The Atlantic Coastal Plain
B. Drainage Patterns- determined by the underlying bedrock, and way streams connect
1. Dendritic, Radial, Rectangular, Annular
VI. Fossils – the remains or the evidence of a living thing
A. Types of Fossils
1. mold- an empty space in the shape of the organism
2. cast- occurs when minerals fill a mold and harden into the shape of the original
organism
3. imprints- occurs when leaves and light weight organisms leave an impression in
soft sediment like mud, that later hardens into rock
4. amber- occurs when insects are trapped and become embedded in resin
5. ice- occurs when an organism is preserved in ice (woolly mammoth)
6. tar- occurs when animals are trapped in tar pits (LaBrea Tar Pits -Cali)
7. Petrified- occurs when minerals dissolved in ground water gradually replace the
original tissues of plans/animals
8. carbonaceous film- occurs when carbon in tissues of organisms leave a
residue/thin film of carbon on sediment which then hardens into rock
B. Why do we study fossils?
1. Fossils indicate the variety of life forms that once existed on Earth
2. Fossils show how organisms have evolved over time
3. Fossils indicate how Earth’s surface has changed over time (uplifting)
4. Fossils give clues to Earth’s past climate.
5. Fossils tell us about the appearance and activities of extinct organisms
VII. Relative Dating
A. Relative Age- the age of something compared to something else.
B. Geologic Column- an ideal sequence of rock layers created by combining data from all
known rock sequences at various locations
1. Original Horizontality- Due to gravity, sediments are deposited horizontally,
parallel to Earth’s surface.
2. Principle of Superposition- In undisturbed sedimentary rock layers, the oldest
rocks are round at the bottom, and the youngest are found on top.
3. If the rock layers were disturbed by faulting, then the faulting occurred after the
last layer which was broken by the fault.
4. If the rock layers have been disturbed by folding, then the folding occurred after
the last which has been folded.
5. If an intrusion of magma occurs within a group of rock layers, the intrusion is
younger than the rock layers it goes through.
a. intrusions with “whiskers” show contact metamorphism; causes the rocks
they touch to become baked.
6. An unconformity is a surface of erosion and is usually represented by a wavy line.
Unconformities show a gap in Earth’s history.
a. angular unconformity- erosion of tilted rock strata
b. disconformities- erosion of parallel rock strata
VIII. Rock Correlation- matches the age of rock layers from different locations
A. Methods of Correlation
1. Index Fossils – a fossil that is used to date rock layers in which it is found
- an organism that lived during a relatively short defined time
- must have a wide distribution geographically
2. Walking the outcrop/observing -physically seeing a connection
3. Similar Sequence- similar patterns in areas like age, order, and composition
4. Key Beds- presence of a distinctive layer; ex: volcanic ash
IV. Radioactive Dating- determining the absolute age of a rock or fossil
A. Absolute Age- the measure of how many years old an event occurred or an organism
lived.
B. Radioactive Decay
1. Radioactive/parent element- an atom that has an unstable nucleus that changes
spontaneously or “decays”
2. Decay/daughter- the stable element that is the result of the spontaneous change in a
radio active element.
C. Half-Life- the time it takes for one-half of a radioactive element to change into a decay
element (not affected by outside conditions)
*half life and disintegrations are found on the ESRT pg. 1
X. Geologic Time Scale- divides Earth’s history into sections of time.
A. The units or sections of time include
1. Eon (longest)
2. Era
3. Period
4. Epoch (shortest)
B. The boundaries between geologic time intervals represent major extinctions.
C. You must be able to interpret ESRT pg 8,9 and calculate different intervals shown.
D. Earth formed about 4,600 million years ago.
XI. Weather- the state or condition of the variables of the atmosphere for a location at a given
period of time.
A. Energy from the sun  the uneven heating on earth causes weather!
B. Angle of Insolation
a. Low-latitudes(0°)=high angle of insolation(90°)= direct light= high intensity
b. Mid-latitudes (30°N/S-45°N/S)= medium angle of insolation (60°)= moderate
intensity
c. High-latitudes(>60°N/S) = low angle of insolation (<30°)= indirect ligh= low
intensity
C. Weather Instruments
a. Barometer- measures air pressure
b. Sling psychrmotor- measures relative humidity
c. Rain gauge measures rain fall
d. Weather vane- measures wind direction
e. Anemometer- measures wind speed
f. Thermometer- measures temperature
D. Earth’s Atmosphere- the envelope of air (mixture of gases) that surrounds earth
a. Composition of elements in atmosphere read off chart on ESRT 1, 14
E. Temperature vs. Heat
a. Temperature- the measure of the average kinetic energy of the atoms or
molecules in a substance.
b. Heat- total amount of energy (kinetic/potential) possessed by the molecules in a
piece of matter.
c. Conduction- Transfer of heat by the collision of molecules. Requires contact.
d. Convection- Transfer of heat by actual movement of a heated fluid (gas or liquid)
e. Radiation- Transfer of heat in the form of electromagnetic waves. No medium
required.