1. Do Now 2/26/14 What do contour lines on a topographic map indicate?
If one line on a topographic map reads 200 km and the next line reads 250 km, what is the index contour?
How can metamorphic rocks form?

2. Weathering of Rocks
2 main types
Mechanical weathering requires physical forces to break rocks into smaller pieces.
Chemical weathering requires the transformation of rock into one or more new compounds.

3. Mechanical– Frost Wedging
water forces its way into the cracks
water freezes which causes the crack to expand
more water fills the cracks & freezes
rocks split apart

4. Mechanical Weathering – Unloading & Exfoliating
rocks are uplifted and the rock surface is eroded away
dome shaped rock
outer edges are cracked and break loose – exfoliating.

5. Mechanical Weathering – Biological Activity
plants & animals burrow through the rock
humans blast rocks apart looking for minerals & deforestation
dead organisms produce acids that dissolves the rock

6. Chemical Weathering – Water
Most important agent of chemical weathering
dissolves various gases from the atmosphere and soil
causes a reaction with minerals in the rocks
Oxygen reacts with the metals in the rocks to produce oxide (rust) to create a yellow to reddish-brown rocks
Acids dissolve away the surface of the rocks

7. Chemical Weathering – Spheroidal Weathering
Rocks are eroded by water & become rounded
outer straight edges will always erode away first

8. Rate of Weathering
Rock characteristics - granite rocks are more resistant to weathering while marble (calcium carbonate) dissolves easily with acid rain
Climate
Temperate climates have greater frost wedging & chemical weathering
Influences the types of vegetation that grows in the area
Dry, arid climates & polar climates have slow weathering of rocks

9. Differential Weathering
Softer minerals will wear away quicker leaving peaks & holes in the rock structures
Areas with more cracks will break apart more quickly

10. Lab – Weathering of Rocks
Assignment
Lab – Weathering of Rocks

11. Partner work.
You have to draw a diagram of the rock cycle. It must have:
Color
Be labeled
Have descriptions at each step

13. Exit Ticket 2/26/14
Imagine that you are going on a rock climbing expedition. Take the information you gathered from different texts which involve the rock cycle and decide which of the three types of rocks you would feel the safest climbing and explain why you chose that type of rock.
Expand your answer to include why you did not choose the other two types of rocks as well.