Lecture 1: A Brief History of the Earth

Question 1

Planetary Accretion

Answer 1

Solid materials colliding to form gradually larger bodies

Question 2

Radioactive Decay

Answer 2

Spontaneous breakdown of an atomic nucleus which releases energy and matter

Question 3

Gravitational Differentiation

Answer 3

The transformation of a planet by gravitational forces into a body whose interior is divided into concentric layers that differ from one another both physically and chemically

Question 4

Igneous

Answer 4

Formed through the cooling and solidification of magma or lava

Question 5

Volcanic Outgassing

Answer 5

Gases released from inside the Earth through a volcano

Question 6

Greenhouse Gas

Answer 6

A gas that absorbs infrared radiation, thus contributing to the greenhouse effect

Question 7

Comet

Answer 7

Cosmic snowball of frozen gases, rock and dust that orbits the sun

Question 8

Heavy Bombardment

Answer 8

A time early in the early history of the solar system when planets were subjected to very frequent crater-forming impacts

Question 9

Chemoautotrophs

Answer 9

Use energy from chemical reactions to synthesise their own materials (food)

Question 10

Microfossils

Answer 10

The physical traces of individual microorganisms preserved in rocks (not proper fossils)

Question 11

Stromatolites

Answer 11

Rocks consisting of alternating layers of sediment and bacteria

Question 12

Chemofossils

Answer 12

Fossils consisting only of chemicals remaining from the decomposition of a living organism

Question 13

Cyanobacteria

Answer 13

A group of microorganisms that produce carbohydrates and release oxygen through photosynthesis and that probably originated the process early in life’s history

Question 14

Banded Iron Formations (BIFs)

Answer 14

Alternating layers of iron oxides and iron-poor rock

Question 15

Red Beds

Answer 15

Rocks laid down in riverine (etc) environments containing lots of Fe3+

Question 16

Evolutionary Radiation

Answer 16

The relatively rapid evolution of many new types of organisms from a common ancestor

Question 17

Fossil

Answer 17

A trace of an organism that has been preserved in the geologic record

Question 18

Cambrian Period

Answer 18

First period of the Phanerozoic eon (beginning with Cambrian explosion)

Question 19

Mass Extinctions

Answer 19

A short interval during which a large proportion of the species living at the time disappear from the geologic record