Lectures 2-4 Flashcards
The three main tock types
Igneous, Sedimentary, and Metamorphic
Law of Original Horizontality?
Sedimentary layers are deposited horizontally and continuously
Law of Superposition?
Each layer of sediment is older than the layer above it and younger than the layer below it
Law of Cross-cutting Relationships?
If a fault or other body of rock cuts through another body of rock then it must be younger in age than the rock through which it cuts
Law of Inclusions?
Clasts in a rock are older than the rock itself
Crust
The outermost layer, on top of the mantle
Mantle
It has upper and lower sections and includes the asthenosphere, iron, and magnesium-rich silicate minerals
Core
Mostly iron metal (very dense), solid inner core, liquid outer core
Asthenosphere
The top part of the upper mantle where it is plastic, and partly molten
Lithosphere
includes the rigid part of the mantle and the overlying crust, rides on the plastic asthenosphere
The three ways we know what the interior of the Earth looks like
Density, Seismic data, Meteorites
Main geologic processes active on Earth today
Tectonics, volcanic activity, mass wasting, water, wind, ice -> erosion and deposition of sediment, impact crater, life
Fusion
The combination of two or more nuclei to form a different, heavier, element; the by-product is radiation
Supernova
The cataclysmic explosion of a star, as a result of internal nuclear reactions
Nebula
Dust in space with a density of 1,000 gas molecules/10cm^3
Gravitational Collapse
When molecules are concentrated, attracted to each other; may be triggered by a nearby supernova
T Tauri Star
Stars that are similar to the Sun, but only about 1 million years old
Proplyds (Protoplanetary disk)
Disks of dust and gas around young stars, places where planets are possibly forming
Refractory
Materials that condense at very high temperatures
Volatile
Materials that condense at very low temperatures
Meteorite
An extra terrestrial rock that has fallen through our atmosphere
The two main sources of information for how the solar system formed
Astronomical observations and meteorite studies
Planetesimal
Small solid bodies, ~100km across, that formed from grain-to-grain accretion of dust
Accretion
Solids come together to form larger objects through gravitational attraction and collisions
Differentiation
The separation of materials in a planetary body according to density and chemical affinity
Conduction
The vibrational energy of an atom is transferred to adjacent atoms
Convection
Warm material expands and moves upwards, displacing cooler, denser materials downwards
Radiation
The emission of electromagnetic waves from a hot body’s surface to its surroundings
Law of Cross-cutting Relationships for impact cratering
If an impact crater, fault, or body of rock cuts through another body of rock then it must be younger than the rock through which it cuts
Three things that must be explained by any model for how the solar system was formed
- The planets orbit in the same plane
- They orbit the Sun in the same direction
- The Solar System is zoned from rocky inner planets to gas-rich outer planets to ice-rich comets
What Earth most likely looked like 3.8 Ga ago
Most of the surface is covered in an iron-rich ocean, a carbon dioxide-rich atmosphere, and surface temperature over 75 degrees
