Earth Science 1G03, Study Guide Final

Relative Age

The age of an object/event relative to the age of other objects/events not given in time units

Absolute Age

The age of an object/event in years

Cross-Cutting

Any feature that cuts across another feature must be younger

Unconformity

- gap in the sedimentary record

- deposition stopped, an interval of erosion removed some of the previously deposited rock, and finally deposition was resumed

Three types of unconformities

1) Disconformity

2) Angular Unconformity

3) Nonconformity

Disconformity

Sedimentary layers above and below the unconformity are parallel

Angular Unconformity

Horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers, producing an angular discordance with the overlying horizontal layers

Nonconformity

Metamorphic or igneous rocks underneath sedimentary strata

A "time gap" (missing rock) can only be measured by...

Fossils and radiometric dating

Faunal Succession

Fossils succeed one another in definite

and recognizable order

Index Fossils

- used to identify geologic periods

- existed only for a short time interval but had a wide geographical distribution

Stratigraphic Correlation

- uses principle of faunal succession

- index fossils

- each formation contains a unique group of fossils

- rocks containing the same fossils are the same age

Order of geologic time scale (oldest to youngest)

Precambrian, Paleozoic, Mesozoic, Cenozoic

What is used to determine the absolute age of rocks?

Radioactive isotopes

Radioactive parent isotopes are transformed into...

Non radioactive, stable daughter isotopes

Half life

- time required for half of a given parent isotope to decay to its daughter product

- rate of decay is assumed to be constant.

Effective time range

- the interval over which a radioactive isotope yields useful dates

- approximately 10 times the half-life

Steps of radiocarbon dating

1) Radioactive carbon created in atmosphere from cosmic radiation

2) Carbon is incorporated into living tissues

3) When organism dies, 14C decays to stable 14N

4) Ratio of 14C to 14N is related to time of death

What type of rock yields the most accurate radiometric ages?

Igneous

What type of rock is often problematic when using radiometric dating?

Sedimentary

What are the oldest known minerals? Where are they found? How old are they?

Zircons; Australia; 4.3 billion years old

How old is the Earth?

4.6 billion years old

What colour are contour lines on a topographic map?

Brown

What is the only situation in which contour lines can cross?

When an overhanging slope exists

The zero line for Latitude is called the ___________ and is located at __________.

Equator; 0 degrees

How are Latitude and Longitude represented on topographic maps?

Black numbers and black and white bars

How is the UTM grid system represented on topographic maps?

Blue numbers and blue lines

Magnetic declination is expressed in ___________ and ___________.

Degrees and minutes

What kind of slope do contour lines show when they are close together? When they are far apart?

Steep; Gentle

What is the formula for calculating slope gradient?

Vertical distance/horizontal distance

What does UTM stand for?

Universal Transverse Mercator

The units of latitude and longitude are __________, __________, and __________.

Degrees, minutes, and seconds

1 degree is equivalent to how many minutes?

60

For an organism to fossilize, it needs to have 3 things. What are they?

- hard parts

- anoxic conditions (low oxygen)

- rapid burial in low energy environments

In modern day shallow-water

environment:

____% of organisms have sturdy shells

____% of organisms have fragile shells

____% or organisms are soft-bodied

30, 40, 30

Describe freezing (preservation)

- frozen animals show information about diet

- can see muscles and fat

- fur/skin condition is rare to find

- potential for genetic information

- ex. mammoths

Describe preservation in amber

- ex. insects

- tree sap that comes from conifers

- found near North Sea

- can preserve things as delicate as wings

Describe preserved/replaced bones

- more common

- replacement happens because fluids move through rocks

- if bones are left in ground for long time, water will replace bone material with minerals

- if rock is mostly bone, it will feel sticky

Describe molds and casts (preservation)

- if outside of shell pushes into sediment, it will leave imprint

Describe carbonization

- during lithification, everything that is not carbon will disappear

- all that remains is a thin layer of carbon

Trace fossils

- ex. dinosaur footprints, worm burrows

- information about depth of water

- can categorize based on shape and orientation

What was the extraordinary fossil shown in class?

Archaeopteryx from the Solenhofen Limestone (shows the imprint of feathers)

What are the three domains of life?

Bacteria, Archaea, Eukarya

What kingdoms are in the domain Eukarya?

Protista, Fungi, Plantae, Animalia

9 types of marine fossils

1) Trilobite

2) Gastropod

3) Bivalve

4) Brachiopod

5) Bryozoan

6) Crinoid

7) Graptolite

8) Ammonite

9) Coral

What type(s) of fossils are found easily on campus?

Crinoids

Where are many large ammonites found in Canada?

Fernie, B.C.

What animal are ammonites related to?

Modern squids

What era are ammonites from?

Mesozoic

Modern coral is __________ , whereas Paleozoic corals are either __________ or __________.

colonial; colonial or solitary

What era are bivalves from?

Cenozoic

What fossils are from the paleozoic era?

Brachiopods, coral, graptolites, and trilobites

Where are paleozoic fossils commonly found in Canada?

Ontario (Arkona and The Blue Mountains)

Where are mesozoic fossils commonly found in Canada?

Alberta and B.C.

Earth materials move downhill due to __________.

Gravity

How is cohesion of sand grains influenced by water?

Surface tension of water increases cohesion of grains if there is only a small amount of water

List the following scenarios in order of increasing cohesion:

- Dry sand

- Water-saturated sand

- Damp sand

1) Water-saturated sand

2) Dry sand

3) Damp sand

Flows are caused by:

a. damp materials

b. water-saturated materials

c. dry materials

Water-saturated materials

What is the slowest form of mass wasting?

Creep

What is rock slide?

Movement of blocks of bedrock

What case study is associated with rock slide?

The Frank Slide

What are 4 triggers for mass wasting?

1) Unfavourable geologic structures

2) Heavy rainfall or snow melt

3) Earthquakes

4) Unfavourable artificial structures

Describe the Gros Ventre Slide

- weak layers of shale supporting heavy loads

- groundwater level was high due to snow melt and spring rain

- erosion of slope by river

Describe the Vaiont case study

- dam increased ground water level

- increased water pressure caused slope to move (rockslide)

- rockslide into reservoir pushes water into dam reservoir, over dam, and into communities downstream

What trigger(s) for mass movement caused the Frank Slide?

Unfavorable geological structures

What trigger(s) for mass movement caused Gros Ventre?

Unfavourable geological structures and heavy rainfall

What trigger(s) for mass movement caused Vaiont?

Unfavorable geological structures and unfavorable artificial structures

List three landslide hazards

- roads undercut slope

- sprinklers and cesspools add water to slope

- houses and cars add weight to slope

- streams undercut slope

- natural vegetation is removed and lawns are planted

Drainage basin

the total area drained as water reaches the ocean via rivers and streams

Three types of transport loads

Dissolved load - dissolved ions carried in water solution (35% of suspended load)

Suspended load - particles carried in suspension in flowing water

Bed load - particles dragged along stream bottom

What is capacity (streams)?

The amount of material a stream can carry

As velocity of a stream ___________, sediment comes out of suspension and settles on bottom and sides of channels.

Decreases

______________ streams deposit finer material.

Slower

Energy (velocity) required to erode a particle is ___________ than that required to keep it in suspension

Greater

Very fine particles require ___________ velocities to be eroded due to electrostatic forces.

Higher

Rivers show a ___________ profile that is different for each river.

a. convex

b. concave

c. square

d. colloidal

Concave

What is the gradient of a river profile?

Steepness of channel over a specified length

What is the long profile of a river?

Cross section along channel showing gradients from source to mouth

What is the base level of a river?

Limiting level below which stream can not erode (ocean or lake usually)

What happens to the base level of a river when a dam is built?

New base level forms upstream of dam

What are braided streams?

- A stream that has

multiple channels

divided by sediment

bars

- Braided streams form where the sediment load is so heavy that some of the sediments are deposited as shifting islands or bars between the channels

Braided streams occur in rivers with _______ speed, _______ slope, and/or _______ sediment load

Low, low, large

What are meandering streams?

- deflection of current causes erosion on cut bank

- increase of current increases erosion (cut bank)

- decreases of current increases deposition (point bar)

What are deltas?

- landform that forms from deposition of sediment that is carried by river as the flow leaves the mouth and enters slower-moving water (lakes, oceans)

What percentage of fresh water on Earth is groundwater?

95%

List the three groundwater zones

Unsaturated zone - water and air fills pores

Water table - upper limit of saturated zone

Saturated zone - water fills pores

The water table is _______ under hills and _______ under valleys.

Higher, lower

Where is the saturated zone located in relation to the water table?

Below

In what type of materials are pores connected?

a. non-permeable

b. permeable

Permeable

What is porosity?

Porosity = amount of space within a rock (volume of a rock that is not actually rock)

What is permeability?

How connected the pores are

Fine sediments have ______ permeability and coarse sediments have ______ permeability.

Low; high

Groundwater flows from _________ to _________ areas.

a. recharge to discharge

b. discharge to recharge

Recharge to discharge

Recharge areas

Areas in which surface water enters groundwater zone (usually upland areas)

Discharge areas

Areas in which groundwater emerges at the surface

What is an aquifer?

A body of sediment that is both porous and permeable

Water can be pumped from a well ________ than an aquifer can recharge.

a. faster

b. slower

Faster

What is a cone of depression?

Lowering of water table as water is pumped from a well (forms cone shape)

Artesian wells

Drilled hole in a confined aquifer releases pressure and pushes water up (water under pressure flows at surface)

What are springs?

Locations of natural groundwater discharge