Weathering Presentation Chapter 10 Sections 1 & 2

Old and New Mountains The Appalachian Mountains appear very different from the Sierra Mountains. The Appalachians are smaller, rounded, gently sloping, and covered with plants. The Sierras are twice as high, and very rocky and steep. The Appalachians are much older so they have had more time to weather and erode.

Weathering The natural processes that break down exposed rock and turns it into soil. Heat, cold, water, and ice, and wind all can weather rock. Rocks get weathered into smaller and smaller pieces, forming the basis of soil.

Agents of mechanical weathering Wind Water Ice Gravity Animals Plants

Mechanical Weathering Mechanical (physical) weathering when rock is physically broken into smaller pieces. Ice: The alternate freezing & thawing of soil and rock, called frost action Abrasion: the grinding & wearing away of rock surfaces through the mechanical action of other rock or sand particles.

Mechanical Weathering Wind, Water, and Gravity carry rocks, causing them to abrade against one another.

Ice Wedging Chapter 10 ering ClickH:\weathering videos.docx below to watch the Visual Concept.

Mechanical Weathering Plants As a plant grows, the force of the expanding root becomes so strong that it can break a rock apart. Animals any animal that burrows causes mechanical weathering by mixing/digging through soil and rock particles.

Chemical Weathering Water Acids in groundwater Acids in living things Rocks break down in as a response to chemical reactions Faster in warm, humid areas Agents of chemical weathering: Water Acids in groundwater Acids in living things Air

Chemical Weathering Water Acid Precipitation Acid in groundwater has weathered limestone to form Rusty’s Cave in Dade County, Georgia. Chemical Weathering Water even hard rock, such as granite, can be broken down by water Acid Precipitation high level of acidity in acid precipitation causes very rapid weathering of rock Acids in Groundwater acidic groundwater comes into contact with limestone, it is dissolved & forms karst features.

Chemical Weathering of Granite

Chemical Weathering Acids in Living Things Air Some living things, such as lichens, produce acids that can slowly break down rocks. Air Oxygen in the air causes oxidation--a chemical reaction in which an element, such as iron, combines with oxygen to form an oxide. Lichens, which consist of fungi and algae living together, contribute to chemical weathering.

Mechanical and Chemical Chapter 10 Weathering Mechanical and Chemical Weathering Click below to watch the Visual Concept. /H:\weathering videos.docx

Differential Weathering What Is Differential Weathering? process where softer, less weather resistant rock wear away & leaves harder, more weather resistant rock.

The Shape of Rocks Surface Area The more surface area of a rock that is exposed to weathering, the faster the rock will be worn down. Increasing the Rate of Weathering If a large rock is broken down into smaller fragments, weathering of the rock happens faster.

Surface Area and Volume

Weathering and Climate What Is Climate? Climate is the average weather condition in an area over a long period of time. Temperature and Water Rate of chemical weathering happens faster in warm, humid climates. Water also increases the rate of mechanical weathering.

Weathering and Elevation High Elevations Rocks on a mountain, are exposed to more wind, rain, and ice & weathering occurs faster. Steep Slopes The steepness of mountain slopes increases the effects of mechanical and chemical weathering. Steep slopes cause water and sediments to quickly run down the side of the mountain.