Earth Science

Question 1

What is a kimberlite?

Answer 1

A volcanic pipe that brings diamonds and other minerals to the surface.

Question 2

Where do diamonds form?

Answer 2

Mantle

Diamonds only form under a lot of pressure.

Question 3

How do concentrations of gold form?

Answer 3

There are two concentration steps.

(1) deep inside the Earth’s crust a hydrothermal solution (hot hot water containing salts like potassium and sodium chloride) flows between rocks containing gold. The rocks bind with the chloride ion from the water to form gold chloride. This hydrothermal solution with dissolved gold can move and be concentrated in higher areas in the earth’s crust. As the hot solution cools, it forms a hydrothermal gold deposit.
(2) on the surface there is a source region that has rocks containing gold, a river erodes that region and moves metal deposits to a common place further downstream to deltas and possibly beaches, further concentrating the gold.

Question 4

What is chromium used for?

Answer 4

Chromium is valued for its anti-corrosive properties and hardness.

It is a component of stainless steel. Steel is carbon and iron. Stainless steel is iron and chromium. The chromium makes the product harder and more resistant to rust.

Question 5

What is an alloy?

Answer 5

A combination of at least two elements where at least one of the elements is a metal.

Question 6

How can bronze be made?

Answer 6

Bronze is a mixture of copper (> 70%) and tin and can be made by melting both metals and mixing them.

Question 7

How can brass be made?

Answer 7

Brass is a mixture of copper and zinc and can be made by melting both metals and mixing them.

Question 8

In what kind of rocks is chromium fairly abundant?

Answer 8

Mafic rock

i.e. rocks rich in magnesium and iron

Question 9

What are the 3 main rock types?

Answer 9

Igneous
Sedimentary
Metamorphic

Question 10

How are igneous rocks formed?

Answer 10

Igneous rocks form when lava or magma (molten rock) cools and solidifies.

Question 11

How are metamorphic rocks formed?

Answer 11

They are formed from other rocks that are changed from heat or pressure (nb they are not made from molten rock - that’s igneous rocks).

Question 12

How are sedimentary rocks formed?

Answer 12

They are formed from the accumulation of other rocks. Small rocks are carried by rivers, deposited at mouths of rivers or in lakes, the layers build and the weight of the layers puts pressure on the lowest layers squeezing out the water and forming various different salt crystals that glue the assortment of rocks together.

Over millions of years this process forms sedimentary rocks. Organic material can form some of the layers so sedimentary rock can contain fossils of animals and plants.

Question 13

Why does metamorphic rock usually not contain fossils?

Answer 13

In order to form the primary rock must be subjected to great heat and pressure which would destroy fossils.

Question 14

What is magma?

Answer 14

Liquid rock

Question 15

What are the two main types of igneous rock and what is the difference between them?

Answer 15

Intrusive and Extrusive.
Speed of cooling/ Underground or overground

Extrusive rock is formed from magma that erupts onto the surface as lava. It cools down quickly on the surface of the Earth. Those rocks have small crystals.

Intrusive rocks are formed when magma cools slowly below the surface, deep underground. These rocks form large crystals.

Question 16

What is the difference between lava and magma?

Answer 16

Magma is molten rock found deep underground and when it erupts above ground it is called lava.

Question 17

What type of rock is granite?

Answer 17

Intrusive igneous rock (big crystals)

Question 18

What type of rock is basalt?

Answer 18

Extrusive igneous (small crystals)

Question 19

What type of rock is marble?

Answer 19

Metamorphic

Question 20

What type of rock is slate?

Answer 20

Metamorphic

Question 21

What type of rock is chalk?

Answer 21

Sedimentary

It is made from the shells of sea creatures. It is a type of limestone.

Question 22

What type of rock is coal?

Answer 22

Sedimentary

It is made from plant materials accumulating in swampy environments.

Question 23

How old is the Earth?

Answer 23

4.543 billion years old

Question 24

How old is the sun?

Answer 24

4.603 billion years old

Question 25

What is the Geological Time Scale?

Answer 25

A calendar dividing up Earth’s history by the rock strata ie the different fossils that appear in rock strata over time.

Question 26

What are the four major time eras On the Geological time scale?

Answer 26

Precambrian (pre Wales) - lasted 4 billion years
Paleozoic (old life) - lasted around 290 million years from 541 to 252 million years ago
Mesozoic (middle life) - lasted around 190 millions years from 242 to 66 million years ago
Cenozoic (new life) - fo the last 66 million years

Question 27

What is an alpha particle?

Answer 27

Two protons and two neutrons emitted from the nucleus of a radioactive atom at speed. Although it has the same number of protons and neutrons as Helium, it is not an atom. Unlike helium with its two electrons, it has none.

Question 28

What makes an atom radioactive?

Answer 28

Radioactive atoms are unstable atoms: that is the forces among the particles making up the atom (proton, neutron, electron etc) are unbalanced. An atomic nucleus can become unbalanced if there are too many protons or neutrons. Generally it can happen when there are changes to the number, arrangement or energy of any of the nucleons.

Question 29

What is a nucleon?

Answer 29

A proton or a neutron.

Question 30

What is radioactive decay?

Answer 30

The process undergone by radioactive atoms of releasing protons and neutrons, possibly changing into other atoms, to reach a balanced state.

Question 31

What is radiation?

Answer 31

The spontaneous bursts of energy emitted from radioactive atoms as the attempt to move to a balanced state. This excess energy can be emitted in the form of alpha particles, beta particles, gamma rays and X-rays.

Question 32

What is the difference between ionizing and non-ionizing radiation?

Answer 32

Non-ionizing radiation is weaker although it can penetrate materials and make molecules move (eg microwaves can heat up your food) it cannot create ions ie remove electrons from these materials. Ionizing radiation, however, can.

Question 33

What is a beta particle?

Answer 33

A charged particle (like an electron or positron) released from a radioactive atom when one of its neutrons becomes a proton and an electron. The proton remains in the atom, creating a new element, the electron is released. This happens when there are too many neutrons in an atom. Beta particles have the same mass and can have the same charge as an electron but their origin differs.

Question 34

What are gamma rays?

Answer 34

They have no mass and no charge but are just electromagnetic energy released from a radioactive atom as it attempts to find balance. Similar to visible light rays but with much more energy.