Table of Contents

Title: Rate of WeatheringPage #: 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

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

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 fallBecause of gravity.

Rate of Weathering

Flat Slope = Rocks have Nowhere to go.

Classwork:

• Page 170 questions 1-5.