The Dynamic Planet Flashcards
What are the two Broad Earth Systems?
Endogenic and Exogenic
What is an Endogenic System?
Endogenic system encompasses internal processes that produce flows of heat and material from deep below Earth’s crust (Tectonics, Earthquakes, and Volcanism).
What is an Exogenic system?
Exogenic system involves external processes that set into motion air, water, and ice (Rivers, Landforms, Weathering, Erosion, Oceans, Glaciers).
What is the geologic time scale?
Eon>Era>Period>Epoch
What is the principal of Superposition?
Rock and sediment are always arranged with the youngest bed ‘superposed’ toward the top of a rock formation and the oldest at the base. If they have not been disturbed.
How old is the solar system?
The sun and its solar system are estimated to have formed more than 4.6 billion years ago.
How old is our Earth?
‘Present thinking’ places Earths age at 4.5-4.6 billion years ago.
Define Holocene:
the youngest epoch in geologic time, characteristics of postglacial conditions since the retreat of the continental glaciers, about 11,500 years ago.
When was the last ice age?
the last ice age occurred just prior to 11,500 years ago, during the Pleistocene
How do we know the age of the Earth? (2)
-The oldest rock on Earth is about 4.0 billion years old. The oldest fossil on Earth is about 3.5 billion years old. Maybe earlier?
-Radiometric Dating: Half-life, the decay-rate, is the time required for one-half of the unstable (radioactive) atoms in a rock or fossil sample to decay into “daughter” isotopes.
What is the Principle of Uniformitarianism?
The same physical processes active in the environment today have been operating throughout geologic time.
When was the formation of the Earth?
Earth is thought to have condensed and congealed from a nebula of dust, gas, and icy comets about 4.5 – 4.6 billion years ago.
What were the two dominant materials in the formation of earth?
Silicon and iron
True or False: During the early stages of the formation, Earth’s temperature was so high that silica and iron were all in liquid state.
True
What are Seismic Waves?
Seismic waves travel at a higher speed in the cooler and more rigid areas than in the hotter and softer areas.
How are Seismic Waves used by scientists?
Scientists use seismic waves to probe Earth’s internal structure and density profile. An earthquake or underground nuclear test sends shock waves through the planet.
What could changes in density do in terms of Seismic Waves?
Density changes could induce reflection and refraction of seismic waves
Why is the inner core of the earth solid?
Pressure. Relationships between pressure and temperature
What is Earths core made of?
Inner core + Outer Core
True or False: earths outer core is solid.
False, it is liquid.
How much of the earths mass is the Core Mass?
1/3
What is Earths Magnetism?
The fluid outer core is mainly responsible for generating Earth’s magnetic field, because it is made of circulating liquid molten metallic iron.
In which direction is earths magnetism rapidly drifting?
Northward and westward/
Are magnetic and geographic poles different?
Yes.
What is earths mantle?
Average depth is about 2900 km. Consists of 80% Earth’s total volume. Average density is 4.5g/cm3
What are the two parts of earths mantle?
Lower mantle and upper mantle
What is boundary between the uppermost mantle and the crust above it?
Mohorovicic discontinuity (seismic waves increase rapidly at this zone).
What is the Asthenosphere?
Between the upper mantle and the uppermost mantle, there is a plastic-like layer called the asthenosphere.
When will the plastic layer (AKA asthenosphere) flow?
When force is present.
What does the lithosphere consist of?
Lithosphere consists of the crust and the uppermost mantle
What does Buoyancy tell us?
Buoyancy tells us that something less dense (e.g., wood, ice) floats in something denser (e.g., water).
Where does Earths Lithosphere float?
Earth’s lithosphere (crust and uppermost mantle) floats on the denser layers beneath, much like a boat floating on water.
Where does the lithosphere sink?
Where the load is greater (e.g., under glaciers, or mountains), the lithosphere tends to sink, or ride lower in the asthenosphere.
What is recovery uplift known as?
Isostatic Rebound
What does Isostatic Rebound mean?
The lithosphere is in a constant state of compensating adjustment, or isostasy. (the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression).
Explain Isostatic adjustment:
Isostatic (iso = “equal,” static = “standstill”) refers to the state of gravitational equilibrium between the lithosphere and asthenosphere such that the tectonic plates “float” at an elevation that depends on their thickness and density.
What is the continental drift and who presented it?
In 1912, German geophysicist Alfred Wegener presented an idea that challenged long held assumptions in geology, and three years later published his book Origin of the Continents and Oceans.
What is the evidence of plate tectonics?
-Jig-saw puzzle like match-up of continents.
-Correlation of rock types and structure across continents.
-Occurrence of the mid-oceanic ridge.
-Distribution and types of volcanism, earthquakes, and mountain building
-Age of ocean basin (along mid-ocean ridges)
-The fossil record / biogeography
What is the theory of Plate Tectonics?
Plate Tectonics is the theory that the lithosphere (remember crust + uppermost mantle) is divided into several plates that float independently over the mantle (more specifically, the asthenosphere).
In short, what does Plate Tectonics theory explain?
Plate Tectonics theory describes the motion of Earth’s lithosphere.
What are the two types of Earth Crusts?
Oceanic Crust and Continental Crust
What is the Oceanic Crust?
Oceanic crust, which accounts for about 0.1% of Earth’s mass, can be up to 10 km thick under the oceans but is absent beneath the continents.
What is the Continental Crust?
Continental crust accounts for about 0.4% of Earth’s mass and is present only in continental areas where it is generally 30 to 40 km in thickness.
-Less dense (approx. 2.7g / cm3)
What are the types of Plate Boundaries (3)?
-Convergent Boundary
-Divergent Boundary
-Transfrom Boundary
What is the Convergent Boundary?
Convergent boundaries occur in areas of crustal collision and subduction, where areas of continental and oceanic lithosphere meet, crust is compressed and then lost in a destructional process as it moves downward into the mantle.
-Convergent boundaries form subduction zones, such as off the west coast of South and Central America, along the Aleutian Island trenches, and along the east coast of Japan.
-Convergent boundaries also occur where two plates of continental crust collide, such as the collision zone between India and Asia, and where oceanic plates collide, such as along the deep trenches in the western Pacific Ocean.
What is the Divergent Boundary?
Divergent boundaries occur in areas of seafloor spreading, where upwelling material from the mantle forms new seafloor and lithospheric plates spread apart in a constructional process. An example is the divergent boundary along the East Pacific Rise, which gives birth to the Nazca plate (moving eastward) and the Pacific plate (moving northwestward).
What is the Transform Boundary?
Transform boundaries occur where plates slide past one another, usually at right angles, to a seafloor spreading center. These are the fractures stretching across the mid-ocean ridge system worldwide.
What is the Juan de Fuca Plate?
Tiny plate located between the North American and Pacific plates (off the coast of BC).
