Weathering and Soil Formation Chapter 10 Weathering and Soil Formation

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

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

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.

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.

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?

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.

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.

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.

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.

Weathering and Climate

Weathering and Elevation Why does the peak of a mountain weather faster than the rocks at the bottom of the mountain?

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