Flashcards in Geo Unit 1 Deck (74):
What is the first step of the Scientific Method?
Form a hypothesis
What is a Theory?
Hypothesis that has been repeatedly confirmed
What is a Paradigm?
A comprehensive theory; pulls together seemingly unrelated things
What is a Scientific Law?
A theory that survives rigorous testing over time
The idea that Earth evolved through a series of spectacular events (earthquakes, volcanoes, floods, etc.)
The idea that current geological processes are responsible for the rock record
Are the rates of Uniformitarianism constant?
Is Earth a sphere?
No, it is a prolate spheroid shape (slightly flattened sphere)
What is the radius of the Earth?
+/- 4,000 miles
What was the first thing to happen after the "Big Bang"?
Hydrogen and Helium stabilized
What created more elements after H and He in the creation of the universe?
Fusion in older suns
How did the sun form?
Formed from a nebula collapse
When did Earth accrete to its present size?
4.6 Billion Years Ago
Smaller pieces being joined by gravity
What was the homogenous body of primitive Earth made of?
Iron, Magnesium, Silicon, Oxygen, and gases
Was Earth hot or cold at first?
What was the "Big Thwack"?
An asteroid (Theia) collided with Earth, resulting in the formation of the moon.
What was the iron catastrophe?
The planet differentiated, with the iron melting and sinking to form the core, and silicon and oxygen rising to form the crust (leftovers, Mg Si + O, formed the mantle)
What is the outer layer of earth
How thick is the crust
7 to 70 km thick
What is the difference between continental and oceanic crust
The continental crust is thicker and buoyant, and the oceanic crust is thinner and more dense
What are the characteristics of the mantle
It is hot and plastic, dense from pressure
What are the two parts of the core made of
The outer core is liquid and the inner core is solid iron and nickel
What is the lithosphere
The thin layer underneath the crust
How far down do the tectonic plates reach?
The bottom of the lithosphere
What is the Asthenosphere?
The top layer of the mantle (under the lithosphere)
Geologists look at rock texture and mineralogy to...
What is rock texture?
The arrangement, sizes, and shapes of mineral grains
What are the three main classifications of rocks?
Igneous, Sedimentary, and Metamorphic
What is Igneous rock born of?
What are the two categories of Igneous rocks?
Intrusive and Extrusive
What defines Intrusive Igneous rocks?
They are plutonic, and formed from magma
What defines Extrusive Igneous rocks?
They are volcanic, and formed from lava
What is the difference between fast cooling and slow cooling Igneous rocks?
Fast cooling has small grains and slow cooling has big grains
What is the material that makes up Sedimentary rocks?
Older rocks that have broken down through weathering, erosion, and deposition
What is the process that turns sediment into solid rock?
What are the three steps of Lithification?
Deposition, Compaction, and Cementation
What are the three types of Sedimentary rocks?
Clastic, Biochemical, and Chemical
What are Clastic Sedimentary rocks?
Gravel and Boulders
What are Biochemical Sedimentary rocks?
Ocean Floor and Reefs
What are Chemical Sedimentary rocks?
Chemicals leftover when water evaporates
What defines Metamorphic rocks?
They are changed by heat and pressure without melting (solid state recrystallization)
What are the two types of Metamorphism?
Regional (Heat) and Contact (pressure)
The "all world" supercontinent
Old evidence of Continental Drift?
Related rocks on different continents and Paleoclimates
Modern evidence of Continental Drift?
Paleomagnetism (magnetic reversals recorded in rock) and direct measurement of plate movement
How many big, rigid plates in the Lithosphere?
About a dozen
How much do the plates move in a year?
1 - 10 cm a year
Where does most geologic activity occur?
At and near plate boundaries
What are the three types of plate boundaries?
Divergent Margins, Convergent Margins, and Transform Margins
Define Divergent Margins
The plates are moving apart, with very active volcanism
What are the two types of Divergent Margins?
Continental Rifts and Sea-Floor Spreading
Define Convergent Margins
Plates running into each other
What are the three types of Convergent Margins?
Continent to Continent (mountains, large earthquakes), Oceanic to Continent (oceanic crust subducted, volcano chain), and Oceanic to Oceanic (older crust subducted, volcanic island arcs)
What maintains the size of Earth?
A balance between construction and destruction
Define Transform Margins
The plates slide past each other, with major earthquakes but no volcanoes
Define Ridge Push
Idea that heat forces the plates apart
Strong Gravitational Forces
Closely packed atoms with drifting electrons
Van der Waals Bonds?
What are the three characteristics of Minerals?
1. Naturally Occurring
2. Inorganic Solid
3. Ordered Atomic Structure
What are rocks?
Combinations or aggregates of one or more minerals
What are the most abundant minerals in the crust?
Oxygen and Silicon
What are Silicate Minerals?
Minerals made with the Silica tetrahedron, make up 90+% of the crust
What are the five types of Silicate structures?
Isolated Tetrahedra, Single Chain of Tetrahedra, Double Chain, Sheets, and 3D Framework
What is made of a Double Chain Silicate?
Asbestos (i.e. Chrysotile(safe), Crocidolite and Amosite(bad) )
How are the Tetrahedra held together in Silicate structures?
What is the Piezoelectric Effect?
1. Pressure causes electrical polarity at surface of crystal
2. Applying a charge causes crystal to vibrate regularly
What are the Non-Silicate Minerals?
Carbonates, Sulfides + Sulfates, and Oxides
Carbon and Oxygen, weak bonds and soft minerals
Define Sulfides + Sulfates
Sulfur loses or gains electrons, bonds with wide variety of ions, especially Copper, Lead, and Zinc
Oxygen combines with metallic cations, very resistant and durable minerals