ES2 Q2

• Detrital sediments are made from fragments or sediments of another rock and are classified according to the size of the grains that can be observed in the rock.
• Chemical sediments are formed from the precipitation of a solute.
• Biochemical sediments are formed with organic matter.
• Biochemical or organic sedimentary rocks are formed similarly to a detrital or chemical sedimentary rock but the materials are derived from living things.
• Weathering is the chemical and physical breakdown of rocks.
• Erosion refers to the different processes that create sediments, these include abrasion (scratching of surfaces), falling, dissolution, saltation (rolling of rocks), and scouring.
• Transportation is the ability of wind, water, gravity, and ice to carry sediments to other locations.
• Deposition refers to the accumulation of sediments in an area, which is influenced by the carrying agent, size of sediments and slope of an area.
• Lithification means “to turn into a rock” the general term for the processes that coverts sediments into sedimentary rocks.
• Sedimentary processes involve the weathering, erosion, transportation, and deposition of rock particles as these sediments accumulate in basins, compaction and cementation turn them into cohesive rocks, such as limestone and sandstone.
• These sedimentary rocks serve as a geological record, reflecting Earth's history and environmental changes.
• Wegener could not provide an explanation of exactly what made the continents move.
• Divergent boundaries, also called spreading centers, are the place where two plates move apart.
• New technology led to findings which then led to a new theory called plate tectonics.
• Rift valleys are deep faulted structures found along the axes of divergent plate boundaries.
• A plate is one of numerous rigid sections of the lithosphere that move as a unit over the material of the asthenosphere.
• According to the plate tectonics theory, the uppermost mantle, along with the overlying crust, behaves as a strong, rigid layer; This layer is known as the lithosphere.
• Wegener proposed that the supercontinent, Pangaea, began to break apart 200 million years ago and form the present landmasses.
• Fossil evidence for continental drift includes several fossil organisms found on different landmasses.
• Oceanic Ridges and Seafloor Spreading, a theory by Harry Hess, are continuous elevated zones on the floor of all major ocean basins.
• Alfred Wegener's continental drift hypothesis stated that the continents had once been joined to form a single supercontinent Pangaea.
• Rock evidence for continental drift exists in the form of several mountain belts that end at one coastline, only to reappear on a landmass across the ocean.
• Terrestrial environments are found in the continent, these include lakes, swamps, deserts, and glaciers.
• Terrestrial environments are termed terrigenous, have grains which tend to be more angular and unsorted as they have not travelled far from its source.
• Primary agents of transportation in terrestrial environments are wind, ice, and gravity.
• Transitional environments are found on the edges of a continent, this area is a transition between terrestrial and marine environment.
• Beaches, deltas, and estuaries are examples of transitional environments.
• Marine environments are those that are found under the ocean.
• Weathering is the physical breakdown and chemical alteration of rocks at or near the Earth’s surface.
• Poryphoblast refers to large crystals, ranging from a few millimeters to a few centimeters.
• A volcanic hazard can be described in terms of the volcanic materials or products involved, the behavior of the hazard, and how it poses risks to life and property.
• For volcanic activity to be minimal, magma should either have low gas volumes to generate low pressures or possess low viscosity, enabling easy escape of gas bubbles and preventing pressure buildup.
• Metamorphism, which means “to change form”, is a process that occurs most often at elevated temperatures and pressures.
• Conditions for the formation of metamorphic rocks are found a few kilometers below the Earth’s surface and extend into the upper mantle.
• Contact/Thermal Metamorphism occurs when magma moves into rock; changes are driven by a rise in temperature.
• Hydrothermal Metamorphism occurs when hot water reacts with rock and alter its chemistry and mineralogy; it is common around igneous intrusions and near active volcanoes.
• Agents of Metamorphism include heat, which provides the energy needed to drive chemical reactions, pressure, which causes a more compact rock with greater density, and chemically active fluids, which are hot water-based solutions escaping from the mass of magma, promoting recrystallization by dissolving original minerals and then depositing new ones, and acting as catalysts to promote recrystallization by enhancing exchange of ions.
• Viscosity and gas content also determine the effusive character of an eruption.
• The magma's viscosity must prevent gas bubbles from escaping, allowing pressure to build up.
• Regional Metamorphism results in large-scale deformation and high-grade metamorphism; directed pressures and high temperatures occur during mountain building; it produces the greatest volume of metamorphic rock.