Chapter 1 Flashcards
- What is geology, and what is the difference between physical and historical geology?
a. Geology- What is it?
i. Scientific study of the Earth and its major systems.
b. Subdivisions
i. Physicial Geology- Study of Earth’s compisition, structure, and the processes that shape it
ii. Historical Geology- Study of Earth’s history and history of life.
GEOLOGY- Why Study It?
• Acquiring Knowledge Needed To:
- Obtain natural resources
- Assess and avoid natural hazards
- Prevent or correct environmental damage
• Expanded Awareness of:
- How beautiful and complex Earth is
- How much our survival depends upon understanding how Earth works
THE SCIENTIFIC METHOD
• A systematic, logical way of studying how nature works
• Data is gathered which poses questions
• Hypothesis:
- an attempt to explain the data
- often, more than one is proposed
- tests are devised to find which , if any, are true
• theory: a hypothesis that has tested true
• high probability of being valid
Atmosphere
Gaseous envelope surrounding Earth
• 78% Nitrogen, 21% Oxygen, and 1% Argon, carbon dioxide, and others
EARTH’S MAJOR COMPONENTS
- Geosphere: from the Earth’s surface to its center
- Subdivisions:
- Crust: outermost and thinnest part of Earth. Two types exist
- Continental: thicker, variable thickness, and granitic average composition
- Oceanic: thinner, more uniform in thickness, and basaltic composition
- Mantle: most of Earth’s volume and mass. Denser rock than crust
- Core: molten outer core, and solid inner core. Iron and nickel composition
- Hydrosphere: All of Earth’s water
- 97% is in the oceans
- Atmosphere: Gaseous envelope surrounding Earth
- 78% Nitrogen, 21% Oxygen, and 1% Argon, carbon dioxide, and others
- Biosphere: All life on Earth
• Hydrosphere
: All of Earth’s water
• 97% is in the oceans
• Geosphere
from the Earth’s surface to its center
• Subdivisions:
• Crust: outermost and thinnest part of Earth. Two types exist
• Continental: thicker, variable thickness, and granitic average composition
• Oceanic: thinner, more uniform in thickness, and basaltic composition
• Mantle: most of Earth’s volume and mass. Denser rock than crust
• Core: molten outer core, and solid inner core. Iron and nickel composition
• Biosphere
All life on Earth
DYNAMIC RELATIONSHIP BETWEEN COMPONENTS
- the Earth’s major components exist in “dynamic equilibrium” (changing balance)
- a change in any one results in a change in all the others.
- Not necessarily of the same magnitude
- continental shelves
(below sea level): shallow sea
- continental slopes
(below sea level): steeper slope that connects shallow sea to deep sea
- oceanic ridges
undersea mountain range extending through all the oceans
- transform faults
fractures that cut across a ridge at 90 degree shifting it right or left
- abyssal plains
flat parts of deep ocean
- volcanic island arcs
curving chains of volcanic islands that are next to a trench
• Geologic Time
vast spans of time ranging from thousands to billions of years
• Implications:
- most of Earth’s features can be explained by observable processes acting over geologic time spans according to natural laws
- often called “the principle of uniformitarianism” “The present is the key to the past.”
• The Rock Cycle
continual transformation of rocks from one type to another.
• Caused by internal (underground) and external (surface) processes
- igneous
formed when melted rock (magma) cools and solidifies.
- Sedimentary
formed when rocks weather and erode into sediment then becomes new rock
- Metamorphic
formed when rocks recrystallize without melting, due to heat and pressure deep underground
The Hydrologic Cycle
continuous transfer of water from one repository to another. For example, from sea to the air, then from the air to the land, and then back to the sea
- primary water source= oceans
- primary energy source= sun
- cycle of evaporation, condensation, precipitation, infiltration, and runoff
- effect on the Earth’s surface: most erosion, and most sediment and sedimentary rock is due to the water cycle.
• Plate Tectonics
motion and interaction of rigid, interlocking plate-like segments of Earth.
• Plate interaction causes deformation (bending and breaking)
• This results in tectonic (Earth building) activity such as:
- earthquakes
- volcanism
- mountain formation (orogensis)
• Lithosphere:
- crust + uppermost mantle joined as a single rigid unit
- average thickness= 100 km (62 mi)
- this is what “plates” are made of
• asthenosphere
- highly deformable (plastic) upper mantle
- allows plates to move
• Divergent:
- as two plates pull apart and move away from one another
- as they diverge, magma intrudes into cracks and forms new lithosphere
- almost all occur along the central part (axis) of oceanic ridges
- earthquakes and volcanic activity occur here
• convergent:
- two plates collide and one is forced down under the other into the mantle where it is “recycled”
- this causes quakes and violent volcanic activity
- deep ocean trenches mark where one plate slips under the other
- volcanic island arcs and continental volcanic arcs form next to them
- when two continental plates collide, a great mountain range is formed
• transform:
- two plates are sliding past one another along a transform fault
- there is neither creation nor destruction of lithosphere
- quakes and deformation occur
- features on opposite sides of the boundary are offset
