palaeoenvironmental reconstruction

Question 1

who published a model in the 1970s?

Answer 1

John Imbrie

Question 2

what did John Imbrie’s model demonstrate?

Answer 2

• link between isolation changes and global sea ice vol

Question 3

what did Imbrie’s model suggest?

Answer 3

• chemical composition of G. bullies shells reflects composition of ocean water, effected by waxing and waning of N hemisphere ice sheets
• shells are fossilised down-core
• variation in G.bulloides matches modelled insolation changes

Question 4

when was the existence of Greenland ice cap confirmed?

Answer 4

end of C19th

Question 5

properties of Antarctic ice sheet

Answer 5

• ~4.5 km thick
• preserves record of snowfall through quaternary
• formed 35 mil y/a

Question 6

properties of Greenland ice sheet

Answer 6

• ~3m thick

- formed 18 mil y/a

Question 7

what is the oldest continental ice core?

Answer 7

Antarctica is 800,000 y/o

Question 8

age of Greenland ice core

Answer 8

130,000 y/o

Question 9

what do ice records provide?

Answer 9

• high res. of annual snow bands
• analysis of the ice and the air bubbles trapped inside
• provides records of ppt chemical composition temp
• greenhouse gas conc
• insight into how the earth system operates over time

Question 10

size of ice cores

Answer 10

10 cm diameter but up to 3km long, can be cored by hand up to 40 cm

Question 11

what is used to explain the timing of glacial-interglacial cycle?

Answer 11

solar forcing

Question 12

types of instrumental records

Answer 12

remote sensing

meteorology

Question 13

how is longer term perspective provided?

Answer 13

by proxy data from a range of palaeoenvironmental archives

Question 14

what is an isotope?

Answer 14

variation of a given chemical element which differ in their neutron number

Question 15

what are radioactive isotopes?

Answer 15

they decay over time

Question 16

stable isotopes

Answer 16

do not decay, present in earth system in different quantities

Question 17

18O

Answer 17

8 protons, 10 neutrons, heavy O2

Question 18

what is a depleted O2?

Answer 18

less 18O so lower/ more -ve

Question 19

what is enriched O2?

Answer 19

more 18O so higher/ more +ve

Question 20

examples of biological proxies

Answer 20

plants and animals can indicate temp, salinity and moisture

Question 21

why are biological proxies useful?

Answer 21

limited evolutionary change in quaternary period so taxonomy is strong

Question 22

what is chironomid analysis?

Answer 22

• diverse group of non-biting midges
• ~1200 palaeoarctic species
• require temp, nutrient, pH and O2 conditions

Question 23

what is dendroclimatology?

Answer 23

• climate info in tree rings
• absolute dating
• spatially extensive, often fossilised
• stable

Question 24

what is geochronology?

Answer 24

provides a framework to estimate:
timing
duration
rate

Question 25

-ves of dating techniques

Answer 25

• only suitable in specific environments
• all have specific time intervals over which they operate
• dependence on geological laws- the law of superstition
• all techniques vary on terms of their accuracy = uncertainty