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Science 7 > Earth > Flashcards

Earth Flashcards

1
Q

What are rocks made of

A

Minerals

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2
Q

What are minerals

A 
Naturally occurring
Distinct chemical composition 
Distinct physical properties
Crystalline structure
Inorganic (not living)
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3
Q

What is a gemstone

A

Usually a mineral, one that formed crystals then cut and polished to be made jewelry

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4
Q

How do you tell what a mineral is

A 
Lustre
Hardness
Cleavage/Fracture
Streak
Colour
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5
Q

Lustre

A

Shiny or dull

Metallic or non-metallic

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6
Q

Colour

A

One best describes the minerals appearance

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7
Q

Streak

A

The colour of the powder of the mineral, can be a different colour.
(Making a streak with the mineral on a white, dull surface like paper)

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8
Q

Cleavage or fracture

A

The way the mineral breaks apart
Fracture is rough and jagged break
Cleavage is a smooth flat surface broken

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9
Q

Hardness

A

Hard or soft
Use teh Moh’s hardness scale (scratch test)
1 is the softest and 10 is the hardest

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10
Q

Igneous rocks

A 
formed by melting and cooling of lava or magma
Contain crystals 
Intrusive rocks form below the surface 
Extrusive rocks form above the surface
Granite, basalt, gabbre
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11
Q

Sedimentary rocks

A

Formed when sediments (small bits) settle and form layers
Often contain fossils
Sediments are compacted and cemented together
Sandstone, limestone, conglomerate

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12
Q

Metamorphic rocks

A

Formed below earths surface
Heat and pressure cause existing rock to transform
Marble, Quartzite, Slate

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13
Q

Erosion

A

Movement of soil, rocks and minerals from one place to another
Gradual such as glaciers
Sudden change such as flash floods or earthquakes

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14
Q

What are the 4 agents of erosion

A
  1. Gravity
  2. Glaciers
  3. Wind
  4. Moving water
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15
Q

Weathering

A

The breaking down of rocks into smaller rocks and sediment

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16
Q

The 3 types of weathering

A
  1. Mechanical
  2. Chemical
  3. Biological
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17
Q

Mechanical weathering

A 
Caused by:
Gravity
Temperature change
Wind
Water
18
Q

Examples of mechanical weathering

A

Rock slides
Frost wedging
Rivers

19
Q

Chemical weathering

A

Caused by chemical reactions

20
Q

Examples of chemical weathering

A

Acid rain from pollution

Rust

21
Q

Biological weathering

A

Caused by living things

Can be Mechanical OR Chemical

22
Q

Examples of biological weathering

A

Tree roots in a sidewalk

Lichen or rocks

23
Q

Sedimentation

A

the opposite of weathering and erosion because it’s the process of soil being deposited resulting in teh formation of sedimentary rock

24
Q

Mold

A

Forms when an organism is buried in sediment.
Decays over time leaving an imprint of the organism behind
Like a cake pan

25
Q

Cast

A

Can a form after a mold fossil
Minerals, sediments and water fill it
Over time water evaporates cementing the sediments leaving behind a cast
If a mold is a cake pan a cast is the cake

26
Q

Carbon film

A

All living things contain carbon.
An organism that dies and is buried will break down until all is left is carbon
like a stamp left

27
Q

Traces fossil

A

A fossil that provides evidence that an organism lived rather than part of the organism itself
footprints, bite marks, tunnels, poop

28
Q

Preserved remains

A

Sometimes fossil form leaving the organism very close to their living state, they can form in:

  1. Tar
  2. Amber
  3. Ice
29
Q

Petrified fossils

A

Forms as an organism decays being replaced with minerals and sediment.
Water will seep in while an organism weathers
evaporates leaving the dead organism in the place it died

30
Q

What are the 4 timescale geologically

A
  1. Eons
  2. Eras
  3. Periods
  4. Epochs
31
Q

Geologic timescale

A 
A timescale over the 4.6 billion years of earth broken down into
Eons
Eras
Periods
Epochs
32
Q

Stratigraphy

A

The study of rock layers and what may be found within them (fossils)

33
Q

What are the 4 eras

A
  1. Precambrian
  2. Paleozoic
  3. Mesozoic
  4. Cenozoic
34
Q

Principle of Superstition

A 
Oldest layers are at the bottom 
Youngest layers are at the top
Layers are called Strata
Layers from oldest to youngest:
Shale
Sandstone 
Shale
Lava flow
Limestone
35
Q

Strata

A

Layers in rock

36
Q

Relative age

A

Looking at which strata it’s in to determine how old

If there is a crack goes through the layer it must’ve happened

37
Q

Index fossils

A

Used to determine the relative age of layers

38
Q

Radiometric dating

A

Scientists look at the half life of an enemy in the rock

By looking at how much is left they can tell how long that rock has been there for

39
Q

Half-life

A

The amount of time it takes for half of a radioactive material to turn into another material

40
Q

Radiocarbon dating

A

A form of radio metric dating that scientist look at the half-life of carbon-14
C-14 has a short half-life
Used to measure fossils/living things
After 50 000 years there’s not enough C-14 to accurately measure

Science 7 (16 decks)

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