cenozoic climate change 1

Question 1

what was earths climate like in past

Answer 1

has been cooler - 600 million years ago late pre-cambrian - snow ball earth

sea ice extended to tropics

also warmer times eg greenhouse earth with dinosaurs - cretaceous - little or no ice

Question 2

when did pangea break up

Answer 2

200 mill yrs ago

Question 3

pre cyosphere

Answer 3

antarctica arrived during early cretaceous but not covered in ice sheet -94 mill yrs ago
used to be very warm

latitudinal gradient reduced

Question 4

old v new boundary

Answer 4

old = cretaceous - teritiary (KT boundary)

now K-PG boundary - caused mass extinctions 65 million years ago

Question 5

why did K-PG boundary cause mass extinctions

Answer 5

not 100% sure

old reason - volcanic eruptions, lava flows spread over 1500km killing 50% of all species

new reason - metrorite near mexico - rock boundary which contained 1000 times more iridium than upper and lower layers

veg grew back

Question 6

when was cenozoic

Answer 6

65 mill yrs ago

Question 7

what is tertiary now called

Answer 7

neogene and paliogene

2.5-65 mill yrs ago

Question 8

what stage is at the end of neogene

Answer 8

quaternary 2.6 mill years ago to present

Question 9

what is the quaterary stage divided into

Answer 9

holocene 0-11.7 thousand yrs

plesitocene - 11.7-2.6 million yrs ago

Question 10

what is the eocene climate optimum

Answer 10

happened 50 mill yrs ago

antarctica had rich forests

london warmer crocs

Question 11

what is palaeocene -eocene thermal maxiumum

Answer 11

55.5 mill yrd ago

large amounts of carbon ocean

temp incrase by 7 degrees in just 10,000-20,000 yrs

polar waters were > 20 degrres

Question 12

eocene to oligocene why was there a cooling

Answer 12

cooling of antarctica ice sheet - opening of passages

cooling indicated by heavy oxygen isotope

or

lower atmospheric levels of co2 which got to a tipping point that creates icesheets - 500ppm this shows that if we go above this then we may lose ice sheets and go back to grrenhouse earth

Question 13

what is the mid miocene climatic optimum

Answer 13

17-14.5 mill years ago

higher co2 levels and temp

400-500ppm

temps up by 7 degrees

larger grassland areas

Question 14

what is the pliocene

Answer 14

3.3 - 3 mil yrs ago
warm wet period + 3 dgrees

390ppm

different veg here

Question 15

what is the quaternary period

Answer 15

2.6 mill yrs ago

high frequency of climatic oscillations

intesnity of cold and glacial periods

cyclic changes of cold glaciers and warm interglacials

Question 16

stratigraphic correlations

Answer 16

even no = cold/glacial eg Lat glacial maxium that happened 20,000 yr ago

odd no= warm periods interglacial eg oliocene today