Earth Science Seafloor and Dating Methods

Multiple Choice Review Questions - Earth Science

• Seafloor before echo sounders: Scientists thought the seafloor was completely flat.
• Seafloor age determination: Scientists discovered older rocks further from the mid-ocean ridge by drilling and examining rock samples.
• Magnetic patterns on ocean floor: Alternating bands of normal and reversed polarity were puzzling.
• Seafloor age pattern: Youngest seafloor is near mid-ocean ridges.
• Rock dating technique: Radiometric dating uses the decay rate of radioactive isotopes to determine age.
• Earth's age determination method: Absolute dating helps determine the exact age of Earth.
• Relative rock age determination: Geologists use relative dating to determine if one rock is older or younger than another.
• Igneous rock absolute age: Determining the ratio of decayed to undecayed radioactive isotopes in igneous rocks.
• Regional Metamorphism: Rocks changing due to intense pressure and heat.
• Metamorphism and melting: Exceeding metamorphic conditions results in rock melting to form igneous rock
• Metamorphism description: Changes in a rock due to altered conditions
• Foliation & Lineation: Pressure and recrystallization cause this in deformed rocks
• Geologic Time Scale Order: Precambrian, Paleozoic, Mesozoic, Cenozoic
• Geologic Time Scale: A record of rock and fossil history
• Cenozoic Era: Not the period where gymnosperms replaced angiosperms.
• Dinosaur Extinction: Possibly caused by climate change from an asteroid impact.
• Weathering: The mechanical or chemical breakdown of rocks.
• Physical weathering example: (Not) Plant growth in cracks
• Chemical weathering description: Chemical breakdown of rocks.
• Oxidation example: Rust breaking down rocks over time
• Mountain Formation: Caused by tectonic plates pushing together.
• Mountain formation NOT example: Glacial deposits
• Divergent plate boundary: Two plates moving apart, creating rifts or ridges.
• Tectonic Plate Movement: Driven by convection currents.
• Fossil relative age determination: Fossils in different rock layers are compared.
• Index fossil criteria: An index fossil lives for a short time and has wide distribution.
• Index fossil use: Estimating absolute ages of rock layers.
• Fossil formation: Organisms die and their remains are covered in sediment.
• Relative rock age indicator: Position of layers compared to other layers.
• Dating importance: (Not) Determining particles in fossils.
• Relative dating and digging: Deeper you dig, the older the rocks.
• Relative dating characteristic: Does not involve numerical dating
• Sedimentary rock formation: Sand and gravel become rock from pressure.
• Superposition: Youngest rocks are on top in undisturbed layers.
• Rock layer formation: Erosion and weathering.
• Continental slope: From oceanic to continental crust
• Ocean basin embryonic stage: Rift valleys form.
• Ocean crust meets continental: Ocean crust sinks.
• Tension stress effect: Rocks pull apart.
• Shear stress effect: Rock surfaces slip in opposite directions.
• Mountain formation stress: Compressional stress.
• Ava's clay bar stress: Compressional stress
• Viscosity effect on volcanic eruption: Lower viscosity results in less explosive eruptions.
• Rock melting factors: Temperature, pressure, and mineral composition.
• Pressure effect on rock melting: High pressure increases melting point.
• Magma formation conditions: Low pressure and high temperature.
• Earth as a thermal engine: Internal heat from isotopes.
• Internal heat buildup: Heat escape is slower than heat generation.
• Early Earth heat generation: Collision of gas and dust masses.
• Earth's internal heat source: Radioactive elements.