Download rocks

Science Starter 9-29
WHAT ARE THE THREE TYPES OF ROCKS?
Science Starter 9-30
WHAT IS WEATHERING?
Science Starter 9-29
WHAT ARE THE THREE TYPES OF ROCKS?
IGNEOUS, METAMORPHIC, SEDIMENTARY
Science Starter 9-30
WHAT IS WEATHERING?
A PROCESS IN WHICH NATURAL FORCES BREAK
DOWN ROCKS
Science Starter 10-3
WHAT IS A ROCK?
Rocks
Rocks:
- Naturally formed solid substance that usually are
made up of one or more types of minerals
- What do we use rocks for?
- Building
- Sources of metals
- Artwork
- Pavement
- Rock collections
The Rock Cycle:
- The rock cycle is a set of
processes that form,
change, break down,
and re-form rocks
- Rocks do not follow this
cycle in any particular
order
Three types of rocks:
1. Igneous: forms when molten rock cools and
becomes solid
2. Sedimentary: formed when rocks and other
loose material get pressed together by the
weight of layers of sediment above.
3. Metamorphic: Form from heat and pressure
cause older rocks to form into new types of
rocks
Lets go rock hunting!!!
How do we tell what type it is?
Igneous? Sedimentary? Metamorphic?
Well, turns out its not that easy…
Let’s go check out our local rocks and see what we can
discover!
Homework!
Bring in a cool rock from home!
Igneous Rocks
Intrusive igneous rock:
form from magma
cooling within the Earth.
Ex: granite, quartz
Extrusive igneous rock:
forms when lava cools on
the Earth’s surface Ex:
pumice, basalt
Igneous Rocks
• Large crystals form when very hot
magma cools slowly
• Small crystals form when magma or
lava cools very quickly and doesn’t
allow big crystals to form
• Most igneous rocks are made of
silicate minerals.
• Intrusive and extrusive igneous rock
formations can make long lasting
landforms like intrusive rock
formations, volcanoes, and islands.
Sediments
Sediments are
materials that settle
out of the air or water.
Sediments form
sedimentary rocks when
they get buried and
pressed together.
Some times layers called
strata build on top of
each other
Examples of sedimentary rocks
- Sandstone
- Limestone
- Shell conglomerate
- Coal
- Gypsum, rock salt, and other rocks
formed from evaporated salt water
Metamorphic Rocks
- Metamorphism is a process in which heat
and/or pressure change existing rocks
- Recrystallization occurs when chemical bonds
between rock molecules break and reform
under heat and/or pressure
- Foliation is arrangement of minerals into wavy
or parallel bands.
Weathering
- Weathering is the process by which natural
forces break down rocks
- Mechanical weathering breaks up rocks with
physical forces.
- Ex: Ice wedging, pressure releases, plant root
growth, and abrasion (break down of rocks due
to friction from water or air)
Chemical Weathering
•Chemical weathering
occurs when chemical
reactions occur with
rocks.
•Examples: dissolving in
water, acid rain, rusting
Soil
Humus is decayed organic material.
Humus and sediment build up soil.
Soil horizons are differing layers of
soil. All the soil horizons of an area
are called the soil profile.
How are we affecting the soil?
• Desertification: expanding of deserts due to plants being destroyed
• Construction and development such as roads and buildings
• Mining erodes the soil and leaches possible harmful minerals into the
aquifers.
• Industry and farming pollute soil
• Destructive farming practices (remember the Dust Bowl? Let’s care for our
soil!)