Review For Test 2 Physical Geology

Front 1

What are the two approaches to the dating of rocks?

Back 1

Relative Dating and Absolute Dating

Front 2

Relative Dating

Back 2

Rocks are placed in their proper sequence or order. Only the chronological order of events is determined

Front 3

Absolute Dating or Numerical Dating

Back 3

Date that specifies the actual number of years that have passed since an event occured. It is accomplished with the aid of Radioactive elements

Front 4

List the seven theories of relative dating and who developed them.

Back 4

Nicolas Steno (1669): Principle of superposition, Principle of original horizontality, Principle of original lateral continuity. James Hutton (1726-1797) Principle of Uniformitarianism. William "Strata" Smith (1769-1839) Principle of Biological "or fossil" succession. Charles Lyell(1830) Principle of cross-cutting relationship and the Principle of Inclusion

Front 5

Principle of superposition

Back 5

In any undeformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below

Front 6

Principle of Original Horizontality

Back 6

Most sedimentary rocks formed originally in close-to-horizontal layers (although many have since been moved from their original position).

Front 7

Principle of Original Lateral Continuity

Back 7

Originally sedimentary strata extended in all directions until they either; thinned out, ended abruptly at some kind of barrier or graded into a different kind of sedimentary rock.

Front 8

Principle of Uniformitarianism

Back 8

The concept that the processes that have shaped Earth in the geologic past are essentially the same as those operating today.

Front 9

Principle of Biological (or fossil) Succession

Back 9

Different kinds of plants and animals succeed one another in time because life has evolved continuously; therefore only rocks formed during the same age can contain the same (or similar) assemblage fossils

Front 10

How is the principle of Biological (or fossil succession utilized? Two ways

Back 10

a. correlate contemporaneous rocks from around the world, and to
b. order rock layers into a chronological sequence.

Front 11

Principle of Cross-Cutting Relationships

Back 11

Any geologic feature which cuts across or penetrates another body of rock must be younger than the rock mass penetrated

Front 12

Principle of Inclusions

Back 12

Any rock that contains fragments of an adjacent rock must be younger than the adjacent rock

Front 13

What is the Geologic Time Scale? What relative dating techniques are used?

Back 13

A conglomerate of the Earth's history and division based on the different time periods of life on Earth through the discovery of fossils. It is a relative dating chart and is very disorganized. The relative dating techniques are superposition and correlation

Front 14

How is the Geologic Time Scale divided?

Back 14

Eons, Eras, periods and Epochs

Front 15

What are the subdivisions of Eons and what do they represent?

Back 15

Precambrian (which include Archean and proterozoic) and Phanerozoic (meaning visible life)

Front 16

What are the subdivisions of Eras and how are they divided up according to date?

Back 16

Paleozoic(ancient life) 542mybp-251mybp; Mesozoic (middle life) 251-66mybp; Cenozoic 66mybp to present day

Front 17

Name the Periods for the Paleozoic era?

Back 17

Cambrian, ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, and Permian

Front 18

Name the Periods for the Mesozoic era?

Back 18

Triassic, Jurassic, Cretaceous

Front 19

Name the Periods for the Cenozoic Era?

Back 19

Tertiary, Quaternary

Front 20

What are the Epochs for the Cenozoic Era?

Back 20

Paleocene, Eocene, Oligocene, Miocene, pliocene, Pleistocene, Holocene

Front 21

What is Radiometric Dating?

Back 21

The procedure of calculating the absolute ages of rocks and mineral containing certain radioactive isotopes

Front 22

What is Radioactivity? What are the three types of decay? What is the result of the decay? (i.e. atomic number and atomic mass)

Back 22

Radioactivity is the spontaneous breaking apart of certain unstable atomic nuclei. 1. Alpha particle emission which is the release of particle consisting of 2 protons and 2 neutrons. The result is the Daughter element has an atomic number of 2 fewer and an atomic mass of 4 fewer. b. Beta Emission which is the release of an electron this results in the Daughter nucleus with an atomic number greater by 1 no change in the atomic mass. c. Electron Capture which is the capturing of an electron the result is a daughter nucleus an atomic number that is 1 less there is no change in the atomic mass

Front 23

What is Half Life?

Back 23

The time required for one half of the atoms of a radioactive substance to decay

Front 24

What is the best type of rocks to use radiometric dating? why?

Back 24

Igneous since the radioactive elements and their daughter elements are "locked" in the mineral crystals when the rock solidifies from magma

Front 25

What is Radiocarbon dating? What is the half life? How far back can it be used?

Back 25

The usage of the radioactive isotope C14 to get an absolute dating for organic material. The half life for C14 is 5730 and it can be used to date events back 70000 years.

Front 26

how is C14 produced?

Back 26

It is naturally produced in our atmosphere from cosmic rays interacting with gas particles like Nitrogen and absorbing of neutrons which in turn spit out a proton and form C14

Front 27

What is Mass Wasting?

Back 27

The downslope movement of rock, regolith, and soil under the direct influence of gravity.

Front 28

What is Denudation? What are the three ways it is achieved?

Back 28

the overall wearing away and lowering of continental surfaces, achieved by: 1. WEATHERING (rock disintegration without significant movement) 2. MASS WASTING (the DOWNSLOPE movement of sediment by gravity) 3. EROSION (the removal of sediment by rivers, glaciers, wind..etc.).

Front 29

What factors contribute to mass wasting?

Back 29

Factors contributing to mass wasting: 1. REDUCED COHESION: e.g. water saturation 2. LOADING: increasing the weight on a slope will increase the force pushing the slope material downslope; e.g. water saturation. 3. OVERSTEEPENING: the steeper the slope the greater the pull of gravity acting downslope. 4. UNDERCUTTING: refers to the removal of support from the base of a slope e.g. river erosion, wave attack.

Front 30

How is Mass Wasting classified?

Back 30

It is classified by the Type of Material i.e. rock or debris and the Type of Motion

Front 31

What are the different motions of mass wasting and how are they defined?

Back 31

Fall- refers to the free-falling of detached individual pieces of any size
Slides-when the material moving downslope remains fairly coherent and moves along a well-defined surface.
Flow- Water saturated material moves downslope as a viscous fluid.
Slumps-the downward slipping of a mass of rock or unconsolidated material moving as a unit along a curved surface.
Creep-The slow downhill movement of soil and regolith.

Front 32

What causes Slump to occur?

Back 32

usually a slope has been oversteepened from road construction, or overload of a slope and soil saturation

Front 33

What is an alluvial fan and how is it formed?

Back 33

It is a fan shaped deposit of sediment it is formed when a stream's slope is abruptly reduced

Front 34

What is Groundwater?

Back 34

Water in the zone of saturation

Front 35

What is the Aeration Zone?

Back 35

The area above the water table where openings in soil sediment and rock are not saturated with water but filled mostly with air

Front 36

What is the Water Table?

Back 36

The upper level of the saturated zone of groundwater.

Front 37

What is the Capillary fringe?

Back 37

A relatively narrow zone at the base of the aeration zone. Here water rises form the water table in tiny threadlike openings between grains of soil or sediment

Front 38

What is porosity? What are the open spaces in porosity called?

Back 38

The volume of open spaces in rock or soil. (Uncompacted clay...50% Sand and gravel....20% Solid granite....1-10%) The open spaces are called pore spaces

Front 39

What is baseflow?

Back 39

the flow of groundwater that maintains streamflow during dry periods

Front 40

What is a groundwater recharge? and where does the supply come from?

Back 40

the replenishing of the supply of water from the hills typically causing the water table to rise and supply the stream with water to take to the valley bottom.

Front 41

What is Permeability? Why is it important?

Back 41

The measure of a material's ability to transmit water. It is important because if you have a material like clay it has a high porosity but does not have high permeability so it would lock up the moisture and not allow it to flow

Front 42

Aquiclude/ Aquitard

Back 42

An impermeable layer that either hinders or prevents the free lowing of water

Front 43

Aquifer

Back 43

Permeable rock strata or sediment that transmit groundwater freely i.e. sand and gravel

Front 44

perched water table

Back 44

A localized zone of saturation above the main water table created by an impermeable layer (an aquitard)

Front 45

Spring

Back 45

A flow of groundwater that emerges naturally at the ground surface.

Front 46

Artesian system- What does Artesian mean? What two conditions must exist for it to occur?

Back 46

Artesian applies to any situation where groundwater rises in a well above the level where it was initially encountered. 1. Water is confined to an inclined aquifer that is exposed at the surface or 2. There are aquitards both above and below the aquifer when tapped pressure causes the water to rise

Front 47

Cone of Depression

Back 47

A cone-shaped depression immediately surrounding a pumped well

Front 48

the amount of turbulence in a stream depends on two factors. What are they?

Back 48

Roughness and Flow Velocity

Front 49

How do you calculate discharge or the amount of water moving through a channel?

Back 49

Discharge(Q)=channel cross-sectional area A* Velocity(V)

Front 50

What is Stream Erosion?

Back 50

Stream erosion is the transporting of sediment produced by weathering and moved into the channel by mass wasting

Front 51

What are the three ways a river can move sediment? Which of these is usually the most important component?

Back 51

1.Solution-Dissolved load
2.Suspension-small but visible
3.Bed load-rolling or sliding along the bottom
Suspension is most important because typically it carries the most material

Front 52

What is capacity?

Back 52

The amount of sediment carried

Front 53

What is competence?

Back 53

The largest size particle carried. This increases with increasing discharge and velocity.

Front 54

What is an alluvial deposit?

Back 54

Material deposited by a stream or river

Front 55

What are Channel Deposits? Describe point bars and mid-channel bars.

Back 55

A form of alluvial deposit in which bars occur either as point bars on the inside of river bends or as mid-channel bars which are in the channel itself.

Front 56

Where are Mid- channel bars likely to occur? What kind of stream is likely to result? Where do you see these most often?

Back 56

In streams having large sediment loads and greatly fluctuating discharges. A braided stream is likely to occur . These are likely to occur when large glaciers are drained

Front 57

What is a Floodplain? How is it formed?

Back 57

The flat, low lying portion of a stream valley subject to periodic flooding. It is formed by a meandering river that leaves alluvium due to lateral erosion and the deposits are left on the valley floor. When it floods the alluvium rises above the previous flood banks to produce new ones.

Front 58

Natural Levees

Back 58

formed from the coarse sediment that is deposited after a flood. This forms banks adjacent to the channel

Front 59

Delta

Back 59

An accumulation of sediment formed where a stream enters a lake or ocean.

Front 60

What are the three types of delta deposits? Describe how they form and why.

Back 60

1.Bottomset deposits- A layer of fine sediment deposited beyond the advancing edge of a delta and then buried by continuous delta growth.
2.Foreset Deposits- coarser sediment cascades down the front of the delta
3.Topset deposits-horizontal sedimentary layer deposited on top of a delta during a floodstage. These emerge as the delta rises from the sea.

Front 61

What is a Drainage basin? What limits the drainage basin?

Back 61

the land area that contributes water to a stream. Drainage Divide

Front 62

What typically influences the drainage pattern?

Back 62

The underlying Geology

Front 63

Name the common drainage patterns. Describe the key features and what is underlying to cause these features. Which one is found most often?

Back 63

Radial-typically the result of an isolated volcano cone. streams will diverge from a highpoint
Dendritic-typically a result of the natural slope of the land distinctive in its tree like appearance usually underlying material is resistant to erosion.
Rectangular- appearance is a succession of right angle bends and develops when the bedrock is criss-crossed by a series of joints or faults.
Trellis- pattern where tributary streams are almost parallel. This is the result of underlying land with alternating bands of resistant and less-resistant rock.
Dendritic is most popular

Front 64

What is superimposed drainage? When does it occur?

Back 64

Where the drainage pattern may cut across the underlying geology. this occurs when erosion lowers a stream onto underlying geology.

Front 65

water gap

Back 65

A pass through a ridge or mountain in which a stream flows.

Front 66

Describe the characteristics of the upper reaches of a stream

Back 66

Upper reaches of streams are usually characterized by low discharge, coarse sediment, steep gradient, vertical erosion, steep V-shaped valley, narrow channel, no floodplain, common waterfalls and rapids

Front 67

Describe the characteristics of the middle reaches of a stream

Back 67

higher discharge, finer sediment due to ABRASION, gentler gradient, more LATERAL EROSION, wider valley, beginning of floodplain.

Front 68

Describe the characteristics of the lower reaches of a stream.

Back 68

higher discharge, finest sediment, LATERAL EROSION, wide floodplain - floodplains characterized by point bars, cut banks, meander scars, meander cut-offs, oxbow lakes, levees, yahzoo streams, backswamps, river bluffs.

Front 69

Graded Profile

Back 69

concave shaped profile that results from a steep slope in the upper reaches and a gentler slope in the lower reaches

Front 70

Base Level

Back 70

the bottom of a stream's profile where it can no longer erode could be a lake or sea level

Front 71

How do changes in base level form canyons?

Back 71

The rapid change in the base level forces the stream to downcut

Front 72

How do changes in base level form entrenched meanders.

Back 72

Either base level has dropped or the land that the river was on was uplifted. If base level drops rapid downcutting occurs

Front 73

How do changes in base level form terraces?

Back 73

changes in base level could form a new floodplain at a lower level than the old one thus forming a terrace

Front 74

What is Stratigraphic correlation?

Back 74

Stratigraphic correlation is the practice of "matching up" equivalent bodies of rock from different locations

Front 75

List the three actions a wave can have on land it comes into contact with

Back 75

a.Erode
b.Transport sediment and rock brought to the ocean by rivers
c.Deposit sand and rock down the coastline

Front 76

What is Stratigraphic correlation?

Back 76

Stratigraphic correlation is the practice of "matching up" equivalent bodies of rock from different locations

Front 77

List the three actions a wave can have on land it comes into contact with

Back 77

a.Erode
b.Transport sediment and rock brought to the ocean by rivers
c.Deposit sand and rock down the coastline

Front 78

What is a cut bank?

Back 78

The area of active erosion on the outside of a meander

Front 79

What is a Meander Scar?

Back 79

A floodplain feature created when an oxbow lake becomes filled with sediment

Front 80

What is a Meander cutoff?

Back 80

A short channel segment created when a river erodes through the narrow neck if land between meanders

Front 81

What is an Oxbow lake?

Back 81

The result of a cutoff where the stream has cut through and abandoned the previous meander forming a lake like shape.

Front 82

What is a yazoo stream?

Back 82

A stream that flows parallel to the main stream because a natural levee is present.

Front 83

What is a back swamp? Why do they form?

Back 83

A poorly drained area on a floodplain resulting when natural levees are present

Front 84

What is a distributary?

Back 84

A section of a stream that leaves the main flow and carries water away from the main channel