W3: L12 = Palaeontology [The Anthropocene] (Prof. Benoit)

Question 1

Anthropocene?

Answer 1

= the epoch of humans & the 6th mass extinction.

Question 2

Divisions of geological time attributes? (4)

Answer 2

• Divided into eras, periods, epochs & stages.
• Strata are defined by their fossil assemblage.
• Therfore, to justify making the anthropocene as a new epoch means that humans have significantly changed the biodiversity & geology of the planet.
• All animals affect their environment & change its geology.

Question 3

Egs of how strata redefined by their fossil assemblage? (2)

Answer 3

• K-T boundary.
• P-T boundary.

Question 4

Fossil assemblage of the K-T boundary? (2)

Answer 4

• Asteroid & trapps.
• Extinction of ammonites & dinosaurs.

Question 5

Fosssil assemblage of the P-T boundary? (2)

Answer 5

• Volcanic eruptions (trapps).
• Extinction of trilobites.

Question 6

Egs of how animals affect their environment & change its geology? (3)

Answer 6

• Elephants destroying Acacia trees (transformed forest into savanna).
• Carnivores induced breccia (they filled up the caves with bones).
• Erosion of riverbanks by wildebeests during migration.

Question 7

Since all animals affect their environment & change its geology, how are humans any different than other animals? (7)

Answer 7

• Pollution.
• Eutrophication.
• Urbanism, agriculture, forest clearing & habitat loss.
• Cimate change.
• Species loss.
• Invasive species.
• Other damages to biodiversity.

Question 8

Pollution attributes? (4)

Answer 8

-Pacific trash vortex (7th continent).

• Garbage dumps.
• Sedimentation dominated by plastics.
• Technofossils.

Question 9

Eutrophication attributes? (4)

Answer 9

• Agricultural fertiliser, then
• Algal bloom, then
• Decrease in O2, then
• Accumulation of dead organic material.

Question 10

Urbanism, agriculture, forest clearing & habitat loss attributes? (4)

Answer 10

• 2.7% of land on Earth is occupied by cities.
• 24% is cultivated or used as stock-raising.
• Increase erosion tremendously.
• Destroy wild life resources & split populations.

Question 11

Climate change attributes? (2)

Answer 11

• Global warming.
• Decrease in rainfall.

Question 12

Species loss attributes? (3)

Answer 12

• Direct killing/poaching.
• Overfishing, pollution.
• Mostly affects the megafauna, therefore is not a 6th ME by definition.

Question 13

How will you know that we are in the 6th ME?

Answer 13

When you don’t see cockroaches anymore.

Question 14

Invasive species attributes? (3)

Answer 14

• Plants & animals imported by humans hunt or compete with local species.
• Imported domestic & feral cats are responsible for the disappearance of 63 species (direct hunting).
• Imported rats & mice are responsible for the loss of 75 species (ecological competition & direct hunting).

Question 15

Attributes of other damages to biodiversity? (2)

Answer 15

• Pollution, ocean acidification (& effect on foraminiferans shells).
• Shrinking habitats (shifting baseline).

Question 16

When should the Anthropocene begin?

Answer 16

When did human impact become significant?

Question 17

When did human impact become significant? (9)

Answer 17

• Human impact is neither new nor contemporaneous.
• Comparison of before & after humans’ arrival & species loss.
• First nuclear bomb tests in the 1940s?
• The Industrial Revolution?
• Columbus discovery of America?
• Agricultural Revolution (Neolithic)?
• Appearance of modern human (Quaternary)?
• The oldest evidence of human impact on geology: stone tools (3.3Ma)?
• Until now, there is no consensus.

Question 18

First nuclear bomb tests in the 1940s? (2)

Answer 18

• Enrichment in Cesium & plutonium (easy to trace in the geological record & say “This is the start of the Anthropocene!”).
• BUT human impact on geology is surely much older than that.

Question 19

The Industrial Revolution? (2)

Answer 19

• Well identified by the invention of stream engines (1784).
• BUT what about agriculture? Forest clearing? Invasive species?

Question 20

Conclusion about the Anthropocene? (4)

Answer 20

• Anthropocene would be a time of quick & massive changes for sedimentary processes & biosphere.
• A fast , global & non-selective (but still mostly affecting the megafauna) decline in biodiversity over a short period of time.
• Therefore, the Anthropocene is not an epoch, but a geological boundary!!
• The Anthropocene is dead: it was rejected as a geological time division reflecting human influence, but the concept remains.