GLY 101 1st Edition Lecture 19Outline of Last Lecture I. What Is an Earthquake? Faults and EarthquakesStudy of Earthquake waves Outline of Current Lecture II. WeatheringA. Mechanical Weathering B. Chemical WeatheringIII.Soil FormationA. Soil ProfileCurrent LectureII. Weathering -weathering involves the physical breakdown and chemical alteration of rock at or near Earth’s surface.- there are two types of weathering: mechanical weathering and chemical weatheringA. Mechanical Weathering - mechanical weathering is accomplished by physical forces that breakrock into smaller and smaller pieces without changing the rock’s mineral composition.- more surface area is exposed to chemical weatheringThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy isbest used as a supplement to your own notes, not as a substitute.-types of mechanical weathering: frost wedging, salt crystal growth, sheetingB. Chemical Weathering- involves a chemical transformation of rock into one or more new compound- water plays an important role in chemical reactions- water liberates and transports ions from from some minerals through dissolutionsIII. Soil Formation - parent material, time, climate, plants and animals all effect soil formation- the source of the weathered mineral matter from which soils develop is called the parent material, it is also a major influencing newly forming soil- time is considered the most important factorA. Soil Profile- soil is divided into layers known as horizons- O horizon- consists of largely organic material- A horizon- consists of mineral matter , commonly called topsoil- E horizon- light colored layer, contains some organic material. -Also has washing out of fine soil components, eluviation, and depletion of soluble materials from upper soil, leaching.- B horizon- known as subsoil, where material from eluviation is deposited - B horizon is also known as the zone of accumulation-C horizon- is characterized by partially altered parent material, it has not crossed the threshold that separates regolith from soil- O,A,E, and B horizons together constitute the solum or true
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