Geological History

Question 1

Define ice age

Answer 1

long-term drop in global temperature

Extension of continental ice sheets

Question 2

how many ice ages has earth experience? when was the most recent one? what era was it in?

Answer 2

at least 5 major ice ages

~2mya - 8000 ya

during Pleistocene Epoch

Question 3

What was the most recent glaciation called? what did it cover?

Answer 3

Wisconsian glaciation

covered much of NA in thin ice

Question 4

we are currently in a ______ interval known as the ____ ____

Answer 4

interglacial interval

Holocene Epoch

Question 5

during the last ice age, the two major ice sheets were called what?
how many years ago were they present?

Answer 5

Cordilleran
Laurentide

8000 years ago

Question 6

how many ice sheets are there currently?

Answer 6

2 - greenland and antarctic

Question 7

contraction of ice sheets is dependent on what?

Answer 7

the balance of accumulation vs ablation

Question 8

How did Lake Agassiz form?

Answer 8

during interglacial warming, laurentide ice sheet blocked meltwater from moving into Hudson bay
finally emptied when ice sheets disintegrated leaving areas depressed by water and ice

Question 9

how was Tyrrell Sea formed?

Answer 9

when the ice dam broke, the depression created from the weight of the ice filled with marine water

Question 10

define isostatic rebound

example?

Answer 10

when a depression slowly uplifts reverting back in the direction of its original composition

land is still rebounding near churchill ~1cm/year

Question 11

define moraine

Answer 11

accumulation of glacier debris at edge of a glacier. Ice pushes debris forwards as it accumulates and leaves large masses as it melts

appears as gravel ridge

Question 12

define eskers

Answer 12

sedimentary material deposited by streams flowing under or through glacial ice

Question 13

how do beach ridges and eskers differ?

Answer 13

based on how they are formed

Question 14

define kame

Answer 14

hill/hummock composed of stratified sand and gravel laid down by glacial meltwater
accumulates in a depression on retreated glacier then is deposited on land surfaces with further melting

Question 15

kettle hole

Answer 15

hollow created when buried blocks of glacier ice melt out

becomes kettle lake if there is water in it

Question 16

glacial cycles cause what 3 major changes in the environment

Answer 16

1. climate patterns and zones
2. location and extent of habitat
3. route of dispersal of organisms

Question 17

why is drainage poor in wapusk?

Answer 17

flat and there is permafrost underneath

Question 18

on a species level, if an envr changes and becomes unfavourable, what can a species do?

Answer 18

move
adapt
die

Question 19

define refugia

Answer 19

areas that provide suitable habitat for relict species that have undergone ecological changes

Beringia - alaska and bit of NW and bit of Russia

Question 20

what did species do to cope with physical changes in the envr?

Answer 20

move south
adapt
undergo severe range contractions –> isolation/genetic drift

Question 21

how can movement of animals be mapped?

Answer 21

Pollen record!

• pollen grains washed/blown into lakes accumulation into sediments and provide insight to past vegetative characteristics
• look at current distribution and compare with previous. records
• carbon 14

Question 22

why is carbon 14 so important?

Answer 22

degrades over time TF can measure how much is left to figure out how old it is

Question 23

define evolution

Answer 23

natural selection and survival of the fittest resulting in adaptation over time

Question 24

are caribou and reindeer same or diff?

Answer 24

two genetic lineages cause by location

• range shifted over time
• distinct genetics between the two

Question 25

when did the last mass extinction occur?

which species went extinct?

Answer 25

late pleistocene

large species

Question 26

what caused the mass extinction?

Answer 26

humans and temperature

not proven to but mutually exclusive

Question 27

where does ultimate source of thermal energy come from?

Answer 27

sun

Question 28

3 methods of transfer for energy?

Answer 28

Conduction
Convection
Radiation

Question 29

define conduction

Answer 29

molecule-molecule

• rate dependent on material or substance
• air is poor conductor

Question 30

define convection

Answer 30

movement - current

ex radiator

Question 31

define radiation

Answer 31

via electromagnetic waves
-most in form of visible light
-wavelength related to vibration frequency
-things can absorb radiation
a good absorber reflects little (black pavement)
poor absorber reflects a lot of energy (snow - energy reflected back)

Question 32

on average, how much thermal energy is received by earth?

how does this vary?

Answer 32

~51%

over space and time

Question 33

why are the poles colder?

Answer 33

cause the earth is round
low angle of incoming sunlight
long nights in winter - less sunlight, more heat lost than gained
sun has to travel through more atmo
angle of energy

Question 34

define isolation

Answer 34

total amount of solar radiation energy received on a given surface area during a given time

Question 35

what causes seasonal variation?

Answer 35

1. tilt of the earth
2. orbit around the sun
   - hemisphere tilted towards sun = summer

Question 36

why do ice ages occur?

Answer 36

changes in sunlight reaching the earth
small changes is orbit around sun
**Milankovitch cycles

Question 37

Milankovitch cycles types?

Answer 37

1. Eccentricity
   - orbital path
2. Obliquity
   - tilt
   - axial obliquity
3. Precession
   - earth’s wobble
   - diff N star

Question 38

define boreal

Answer 38

those where snow cover affects animals and plants, or where living organisms have evolved adaptions to snow (Pruitt 1978) and ice