Introduction Flashcards
Geology
from the Greek geo (Earth) and logos (discourse). Geology is the science that pursues an understanding of planet Earth
Physical Geology
Examines the materials composing Earth and seeks to understand the many processes that operate beneath and upon its surface. Precedes the study of Earth history because we must first understand how Earth works before we attempt to unravel its past.
Historical Geology
to understand the origin of Earth and its development through time.
Natural Hazards
volcanoes, floods, tsunamis, earthquakes, and landslides
Resources
water and soil, a great variety of metallic and nonmetallic minerals, and energy
Aristotle
influenced later Western thinking, ideas. unfortunately continued to be viewed as authoritative for many centuries, thus inhibiting the acceptance of more up-to-date ideas
Catastrophism
Catastrophists believed that Earth’s landscapes were shaped primarily by great catastrophes
James Ussher
Catatrophism. Constructed a chronology of human and Earth history in which he calculated that Earth was only a few thousand years old, having been created in 4004 b.c.e.
Uniformitarianism
It states that the physical, chemical, and biological laws that operate today have also operated in the geologic past.
James Hutton
Uniformitarianism. Published Theory of the Earth in 1795. In this work, Hutton put forth a fundamental principle that is a pillar of geology today. ”the present is the key to the past.”
Earth age is…
4.6 billion years old
Current eon, era, period, epoch…
Phanerozoic eon, Cenozoic era, Quaternary period, Holocene epoch
Hypothesis
a tentative (untested) explanation
Theory
a well-tested and widely accepted view that the scientific community agrees best explains certain observable facts
Scientific Method
researchers gather facts through observations and formulate scientific hypotheses
Continental Drift Hypothesis
idea that the continents move about the face of the planet THEORY OF PLATE TECTONICS
Earth Spheres
hydrosphere, atmosphere, biosphere, and geosphere
Hydrosphere
water, continually on the move, evaporating from the oceans to the atmosphere, precipitating to the land, and running back to the ocean again.
Ocean is __% surface, __% total water.
71 percent of Earth’s surface to an average depth of about 3800 meters (12,500 feet). It accounts for about 97 percent of Earth’s water.
Atmosphere
gaseous envelope, very shallow layer, weather and climate
Geosphere
solid earth, depth of nearly 6400 kilometers (nearly 4000 miles), largest sphere,
Biosphere
all life on earth, interacts with all three, concentrated life as the surface
All 4 spheres in…
soil
Earth System Science
study Earth as a system composed of numerous interacting parts, or subsystems
System (and example)
is a group of interacting, or interdependent, parts that form a complex whole (hydrologic and rock cycles)
Earth powered by energy from two sources…
Sun and internal heat
Big Bang happened…
13.7 billion years ago
Nebular Theory: Stages?
proposes that the bodies of our solar system evolved from an enormous rotating cloud called the solar nebula
a shock wave from an exploding star (supernova)—caused this nebula to start collapsing in response to its own gravitation.
evolved from a huge, vaguely rotating cloud to a much smaller, fast-spinning disk
Most of the cloud’s matter ended up in the center of the disk, where it formed the protosun (pre-Sun)
Solar Nubula
gas and microscopic dust grains and other matter ejected ultimately from long-dead stars
Inner Planets
Mercury, Venus, Earth, and Mars
Planetesimals
larger asteroid-size bodies
Meteorites
rocky and metallic pieces that remained in orbit when they survive an impact with Earth.
Outer Planets
Jupiter, Saturn, Uranus, and Neptune
Earth Layers by Chemical Composition
crust (low-density rock)
mantle (high density rock)
core (iron and nickel)
Earth Layers by Physical Properties
lithosphere (solid and rigid: continental crust, oceanic crust) asthenosphere (solid but mobile) lower mantle (solid) outer core (liquid) inner core (solid)
Oceanic Crust
dark igneous rock basalt. younger (180 million years or less) and denser
Continental Crust
Older (4 billion)
varied (granitic rock called granodiorite)
thicker
Mantle
a solid, rocky shell, 82 percent of Earth’s volume
Upper Mantle
Peridotite, (magnesium and iron). extends from the crust–mantle boundary down to a depth of about 660 kilometers (410 miles)
Lithosphere
“sphere of rock” consists of the entire crust plus the uppermost mantle and forms Earth’s relatively cool, rigid outer shell. lithosphere is able to move independently of the asthenosphere. In upper mantle.
Asthenosphere
(“weak sphere”). The top portion of the asthenosphere has a temperature/pressure regime that results in a small amount of melting. Within this very weak zone, the lithosphere is mechanically detached from the layer below. In upper mantle.
Transition Zone
lowest portion of the upper mantle
Lower Mantle
the mantle gradually strengthens with depth. Despite their strength, however, the rocks within the lower mantle are very hot and capable of extremely gradual flow
Core
innermost layer, iron–nickel alloy with minor amounts of oxygen, silicon, and sulfur
Outer Core
a liquid layer. The movement of metallic iron within this zone generates Earth’s magnetic field.
Inner Core
solid due to the immense pressures that exist in the center of the planet.
Continental Margin
portion of the seafloor adjacent to major landmasses. It may include the continental shelf, the continental slope, and the continental rise
Continental Shelf
a gently sloping platform. extends seaward from the shore. Because it is underlain by continental crust, it is clearly a flooded extension of the continents
Continental Slope
boundary between the continents and the deep-ocean basins, a relatively steep dropoff that extends from the outer edge of the continental shelf, called the shelf break, to the floor of the deep ocean
__% earth is ocean basins
__% earth is continents
60 percent of Earth’s surface is represented by ocean basins and the remaining 40 percent by continents.
Cratons
interiors of the continents, relatively stable (undisturbed) for the past 600 million years or even longer. Typically these regions were involved in mountain-building episodes much earlier in Earth’s history
Sheilds
expansive, flat regions composed largely of deformed igneous and metamorphic rocks in the Cratons
Stable Platforms
highly deformed rocks, like those found in the shields, are covered by a relatively thin veneer of sedimentary rocks in the Cratons
