1. Weathering and Soil Formation
Chapter 10
Weathering and Soil Formation

2. Mechanical vs Chemical Weathering
can be caused by
can be caused by I
Acid
Abrasion
found in
which happens several ways by
ice

3. Mechanical vs Chemical Weathering Key
can be caused by
can be caused by I
Ice
Water
Animals
Air
Acid
Plants
Abrasion
found in
Precipitation
which happens several ways by
gravity
Living things
Groundwater
ice
wind
water

4. Chap 10, Sect 2 (Rates of Weathering)
Objectives:
Explain how the composition of rock affects the rate of weathering.
Describe how a rock’s total surface area affects the rate at which the rock weathers.
Describe how differences in elevation and climate affect the rate of weathering.

5. Hard rocks like granite, which is an ____________ rock, weather more S…L…O…W…L…Y… than soft rocks like sandstone, which is a ___________ rock.

7. More surfaces = FASTER weathering!
Let’s count the surfaces on a sheet of white paper. Now, let’s rip it….how many surfaces are there? How about if we rip it again? Again?

8. How Does A Rock’s Surface Area Influence Weathering
In this chapter, you will learn about the processes and rates of weathering. Complete this activity to learn about how the size and surface area of a substance affects how quickly the substance breaks down.
How Does A Rock’s Surface Area Influence Weathering
1. Fill two small cups about half full with water.
2. Add one sugar cube to one cup.
3. Add 1 tsp of granulated sugar to the other cup.
4. GET THE STOPWATCH READY!
5. At the same time as your lab partner, stir the water and sugar in each container using the same technique.
6. Pay attention to how long it takes for the sugar cube versus the granulated sugar, to dissolve in each container.

9. Analysis:
Did the sugar dissolve at the same rate in both containers? Explain.
Do you think one large rock or several smaller rocks would wear away faster? Explain.

10. VS. Weathering takes place on the outer surface of rocks
The more surface area (outsides) that is exposed to weathering, the faster the rock will be worn down
VS.

11. Tech Term:
Differential weathering – the process in which softer, less weather resistant rocks (sedimentary – limestone/sandstone) wear away leaving more weather resistant rocks (igneous – granite/basalt) behind.

12. Weathering & Elevation
Weathering & Climate
Weathering & Elevation
Higher elevations are exposed to more wind, water, and ice
Steepness of slopes causes rainwater to flow quickly, increasing the rate of mechanical and chemical weathering
Chemical weathering is faster in warm, humid climates
Water increases the rate of mechanical weathering
Varying temperatures cause freezing and thawing, thus contributing to ice wedging
They both affect the rate of mechanical & chemical weathering