Table of Contents Title: Rate of Weathering Page #: 54 Date: 1/7/2013

Objective Students will be able to identify variables that affect the rate of weathering.

Rate of Weathering Effects of Climate on Weathering: Climate is the major influence on the rate of weathering of Earth’s materials. –Interaction between temperature and precipitation in a given climate determines the rate of weathering in a region.

Rate of Weathering

Rates of Chemical Weathering: –Chemical weathering occurs rapidly in places with warm temperatures, abundant rainfall and lush vegetation. –Greatest effects of chemical weathering occur along the equator.

Rate of Weathering

Rates of Physical Weathering: –Physical or Mechanical Weathering is most rapid in places with cool climates - Frost Wedging. –Cooler temperatures slow reaction rates of chemical weathering.

Rate of Weathering Rock Type and Composition: –Not all rocks in a climate weather at the same rate. –The types of minerals in a rock play a role in how fast a rock weathers. –Example: Limestone and Marble contain Calcite and will weather more quickly than rocks containing mostly Quartz such as Quartzite and Granite.

Rate of Weathering Weathered Limestone Weathered Granite

Rate of Weathering Surface Area: –The greater is the exposed surface area of a rock the faster it will weather.

Rate of Weathering Topography: –The slope of landscape determines the rate of weathering. –Steep Slope = Faster weathering (rocks will fall down because of gravity.) –Flat Surface = Slow weathering (rocks do not move.) –Steep slopes promote erosion and continuously expose less weathered material.

Rate of Weathering Steep Slope = Rocks fall Because of gravity.

Rate of Weathering Flat Slope = Rocks have Nowhere to go.

Classwork: Page 170 questions 1-5.