Geology
From Halbeeg, the open encyclopedia · Af-Soomaali
2 languages
Geology is the science that studies the structure of the Earth, the rocks and minerals that make it up, the processes of change that occur within it, and the long history of the Earth. It is sometimes called mineralogy, though minerals form only one part of the discipline.
Earth scientists work in two domains: the field and the laboratory. In the field, they collect rock samples, map geological formations, and measure the direction and angle of rock layers. In the laboratory, they analyze the chemistry of rocks, the structure of crystals, and use radioactive isotopes to determine age.
Types of rocks
Rocks are divided into three major types. Igneous rock forms when magma cools, whether inside the Earth or on the surface from volcanic activity. Sedimentary rock forms from sediment and debris that have been compressed and consolidated; it commonly contains fossils. Metamorphic rock has been altered by heat and pressure without completely melting. These three types are linked in what is known as the rock cycle.
Plate tectonics
Plate tectonics explains that the Earth's crust and upper mantle are divided into large plates that move continuously in an orderly way. Where plates move apart, new oceanic crust forms beneath the ocean; where they collide, mountains, volcanoes, and earthquakes are created. The Great Rift Valley of East Africa, which passes through Somalia and Ethiopia, is a well-known example of plates moving apart.
Geologic time
The history of the Earth is divided into periods and a geologic time scale based on changes in fossils and measurements of radioactive age. The age of the Earth is estimated at approximately 4.5 billion years. Rock layers provide evidence of changes in climate, oceans, and life during those periods.
Applications
Geology is used to locate groundwater, oil and gas, mineral deposits for industry, and geothermal energy. It is also used to assess hazards from earthquakes, landslides, and floods, to guide building regulations. Large construction projects such as dams and roads depend on geological reports about the stability of the ground.