1. EXPLORING ROCKS

2. What is a Rock?
A mixture of minerals, rock fragments, volcanic glass, organic matter or other natural materials
Mt. Rushmore in South Dakota is made up of Granite, which contains several minerals

3. What is the Rock Cycle?
#3. What is the Rock Cycle?

4. Rock Cycle Summary
The three major types of rock are igneous, sedimentary, and metamorphic
Rock cycle processes do not create or destroy matter (Conservation of Matter)
The rock cycle occurs very slowly over time
The rock cycle was first discovered by James Hutton in 1788 at Siccar Point, Scotland

5. How is Igneous Rock formed?
When molten rock material, called magma, cools and hardens, igneous rock forms
When magma reaches the Earth’s surface and flows from a volcano, it is called lava

6. 2 Ways Igneous Rocks Form
Intrusive – igneous rocks formed beneath the Earth’s surface
Harden slowly
Extrusive – igneous rocks formed above the Earth’s surface
Harden quickly as lava cools

7. How are Igneous Rocks Classified?
Basaltic – dark colored, dense, from magma rich in magnesium and iron.
Granitic – light colored, lower in density, formed from magma with lots of silica

8. Volcanic Glass
Occurs when rocks are cooled so quickly that few or no mineral grains form.
Pumice and scoria form so quickly that gases are trapped and they leave holes when they eventually escape.

9. Making Sense of the Rock Cycle
Igneous Rocks are the most common rocks on earth, but most are located below the Earth’s surface
75% of the rocks found on Earth’s surface are SEDIMENTARY

10. What is Sediment?
Sediment is loose material such as rock fragments, mineral grains and plant and animal remains
Sediment comes from already existing rocks that have been eroded.
Sediment is moved by wind, water, ice or gravity.
The Grand Canyon

11. Stacked Rocks
Sedimentary rocks form as layer, with the oldest layer on the bottom.
Sometimes forces overturn the layers and the oldest could end up on top. X

12. How are Sedimentary Rocks Classified?
DETRITAL
from erosion and weathering
ORGANIC
From the remains of living things
CHEMICAL
When dissolved minerals
come out of solutions

13. How do sedimentary rocks form?
COMPACTION – Pressure from upper layers pushes down on lower layers. If the sediments are small enough they will now stick together.
CEMENTATION –If the sediments are large, like sand or pebbles, pressure alone can not make them stick, minerals deposit in the gaps and act like cement.
Dissolution of minerals in a solution – the process by which minerals in the solution are left behind. Example: rock salt

14. DETRITAL from weathering and erosion
When rock is exposed to air, water and ice it breaks down, this is weathering (sediment is formed)
When the weathered material moves it is called erosion (allows for a build up of sediment)

15. Organic made up of living things
COAL
Occurs when dead plants are buried under sediments in swamps. These are compacted over millions of years to form an important source of energy
CHALK
Made up of microscopic shells. These were formed between 145 and 65 million years ago

16. CHEMICAL When dissolved minerals come out of solutions
When water that is rich in dissolved salt evaporates, it deposits the mineral halite, which forms ROCK SALT.
**50 % of rock salt is used for road deicing in winter
**10% is used for food

17. What 2 forces are needed to create a METAMORPHIC ROCK?
PRESSURE – rocks beneath the Earth’s Surface are under great pressure from the layers above them
HEAT – temperature increases with depth in under the Earth’s crust

18. Who’s the PARENT ROCK here?
depending on the amount of heat and pressure one type of rock can change into several metamorphic rocks
Heat
pressure
Heat
pressure
shale
slate
Heat
pressure
phyllite
Heat
pressure
schist
gneiss

19. What is a Foliated Rock? Examples
When mineral grains line up in parallel layers.
Examples
SLATE
It’s foliation makes it watertight, used for paving aroun pools
GNEISS
It’s foliation shows up in alternating light and dark bands

20. What is Nonfoliated Rock?
In some metamorphic rock, layering does not occur, the mineral grains grow, but no pattern is formed.
marble
Limestone
The
Sedimentary parent rock