Geology and Soils

Geology (from Greek: γη, gê, “earth”; and λόγος, logos, “speech” lit. to talk about the earth) is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structure, physical properties, dynamics, and history of Earth materials, and the processes by which they are formed, moved, and changed. The field is important in academics, industry (due to mineral and hydrocarbon extraction), and for social issues such as geotechnical engineering, the mitigation of natural hazards, and knowledge about past climate and climate change.

Soil is the naturally occurring, unconsolidated or loose covering on the earth’s surface. Soil is made up of broken rock particles that have been altered by chemical and environmental conditions. Soil is different from its parent rock(s) source(s), altered by interactions between the lithosphere, hydrosphere, atmosphere, and the biosphere. It is a mixture of mineral and organic constituents that are in solid, gaseous and aqueous states. Soil particles pack loosely, forming a soil structure filled with pore spaces. These pores contain soil solution (liquid) and air (gas). Accordingly, soils are often treated as a three state system. Most soils have a density between 1 and 2, and weigh between 60 and 120 pounds per cubic foot. Soil is also known as earth: it is the substance from which our planet takes its name.

• Book 1: Roadside Geology of Texas
• Book 2: Geo-Texas
• Milam County Soils Map

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• 09.16.10_All About Soil
• 03.17.11_GardenSoil