Geology and the Rock Cycle

Geology

• The study of the Earth, its structure, and its history is geology.
• Geology examines the physical forces acting on Earth.
• The composition of rocks and minerals is explored within geology.
• Landforms and their shaping processes are studied in geology.

Rock Cycle

• Rocks transform from one type to another through the continuous process of the rock cycle.
• Igneous, sedimentary, and metamorphic are the three primary rock types.
• Igneous rocks result from the cooling and solidification of magma or lava.
• Sedimentary rocks form as sediments compact and cement together.
• Existing rocks transform into metamorphic rocks through heat, pressure, or chemical reactions.
• Igneous rocks develop from the cooling and crystallization of magma.
• Weathering and erosion break down rocks into sediments.
• Sediments are transported, deposited, compacted, and cemented to create sedimentary rocks.
• Metamorphic rocks are created when heat and pressure alter igneous and sedimentary rocks.
• Any rock type can melt into magma, restarting the cycle.

Plate Tectonics

• The theory of plate tectonics states the Earth's lithosphere divides into moving, interacting plates.
• These plates float on the semi-molten asthenosphere.
• Geological activity such as earthquakes, volcanic eruptions, and mountain building mostly occurs at plate boundaries.
• Convergent, divergent, and transform are the three main plate boundary types.
• Convergent boundaries are where plates collide.
• Divergent boundaries are where plates separate.
• Transform boundaries are where plates slide past each other horizontally.
• One plate forced beneath another at convergent boundaries forms subduction zones.
• Magma rising and creating new oceanic crust at divergent boundaries forms mid-ocean ridges.
• Faults, such as the San Andreas Fault, commonly occur at transform boundaries.
• Mantle convection currents drive plate movement.

Minerals and Resources

• A mineral is a naturally occurring, inorganic solid, having a definite chemical composition and crystalline structure.
• Minerals serve as the building blocks of rocks.
• Quartz, feldspar, mica, and calcite are common minerals.
• Minerals, rocks, and fossil fuels are resources obtained from the Earth.
• Iron, copper, gold, and silver are metallic resources.
• Sand, gravel, limestone, and salt are non-metallic resources.
• Fossil fuels, including coal, oil, and natural gas, come from ancient organism remains.
• Mineral resources are extracted through mining.
• Sustainable use of mineral resources is essential to minimize environmental impact.

Geological Time Scale

• The geological time scale is a chronological dating system relating geological strata to time.
• It divides into eons, eras, periods, epochs, and ages, in descending duration order.
• Eons are the largest geological time divisions, such as Phanerozoic and Precambrian.
• Eras subdivide eons, for example, Paleozoic, Mesozoic, and Cenozoic.
• Periods subdivide eras, like Cambrian, Jurassic, and Quaternary.
• Relative and absolute dating methods construct the geological time scale.
• Relative dating determines rock or event age in relation to others.
• Absolute dating uses radiometric techniques to determine numerical rock or mineral age.
• Radiometric dating relies on the decay of radioactive isotopes.

Fossil Records

• Fossils are the preserved remains or traces of ancient organisms.
• Fossils provide evidence of past life and environments.
• Petrifaction, compression, and preservation in amber or ice are processes of fossil formation.
• The fossil record is incomplete because many organisms do not fossilize well, and many fossils remain undiscovered.
• Scientists use fossil records to understand life's evolution over time.
• Index fossils help correlate rock layers and determine relative ages.
• Paleontology is the study of fossils.
• A chronological record of life's history is provided by fossils found in different rock layers.
• Mass extinction events often appear in the fossil record, indicating significant biodiversity changes.