Transcript Earth Inside Ch 1 - Fort Thomas Independent Schools

Geology is the study of Earth in all of its physical, chemical and biological dimensions
Protosun fuses hydrogen,
becomes the Sun, solar
pressure clears away planetbuilding materials
Current solar
system
Accretion of
planetesimals
Solar nebula
collapses and
rotates
Protoplanetary
disk rotates
faster, flattens,
and protosun
develops
Fig. 1-9, p. 13
Learning Objectives
Explain how the Earth systems or spheres
interact.
Explain the Earth’s internal and external
energy sources
Identify the the Earth’s composition (surface
and interior)
Identify the eons, eras, periods, and epochs
on the geologic time scale.
Relate geologic time to the evolution of the
Earth.
THE EARTH: Systems or Spheres
The Earth is a dynamic, ever-changing planet.
Earth is a complex, integrated system.
The Earth has four spheres that are subsystems of
the larger Earth system.
Each sphere is connected to the other by
processes or cycles.
The internal and external energy sources of the
Earth are the driving mechanism for change.
Fig. 1-2, p. 4
Fig. 1-3, p. 5
The Different “Spheres”
Atmosphere (atmos means ____)
Hydrosphere (hydro means ____)
Biosphere (bio means ____)
Lithosphere (litho means ____)
Using Figure 1-3, explain the interactions
between the different spheres. Using examples,
explain four different interactions between any
of the four spheres.
Table 1-1, p. 5
Earth and Energy
Energy is required for the Earth’s spheres to
interact.
External Energy Source
The Sun
Internal Sources
Heat leftover from formation
• Heat from gravitational contraction
• Heat from extraterrestrial impacts
Decay of radioactive elements
Friction from the movement of the plates and
convection in the mantle
Decay of Radioactive Elements
http://serc.carleton.edu/NAGTWorkshop
s/visualization/collections/RadioDec.htm
l
Unstable element such as Uranium 238
decays to Lead 206
Earth has cooled over time as
radioactive elements decay to stable
elements.
Gases emitted from the interior during this process are likely
the source for the formation of the atmosphere and oceans.
Fig. 1-10, p. 14
The Earth’s Layers
Earth layers result from density differences between the layers
caused by variations in composition, temperature, and pressure.
Core: metal (Fe and small amount of Ni) [10-13 g/cm3]
• Outer liquid core
• Inner solid core
Mantle: iron-rich rock (FeMg-Peridotite) [3.3–5.7 g/cm3]
Crust: aluminum and magnesium rich rock
• Continental Crust: SiAl (rock) less dense [2.7 g/cm3]
• Oceanic Crust: SiMa (rock) more dense [3.0 g/cm3]
Components of the Earth’s Crust
Elements (Si and O are most abundant, traces
of radioactive elements)
Minerals (naturally occurring, inorganic
crystalline solids, gemstones, metals)
Rocks (igneous, sedimentary and metamorphic)
Rocks are composed of minerals.
Natural resources/fossil fuels (coal, natural
gas and oil)
Soils (weathered rock, air, water and organic
material)
Lithosphere and Asthenosphere
Lithosphere is the solid, brittle outer layer of
the Earth composed of:
Oceanic and continental crust
Top part of the mantle
Asthenosphere is the plastic layer of the mantle
directly below the lithosphere over which the
lithospheric plates move.
The lithosphere is broken into many pieces called
plates.
Fig. 1-11, p. 15
Geologic Time
Earth is 4.6 billion years old (as old as the
formation of the solar system)
To a geologist, recent geologic events are
those that occurred within the last million
years.
The Earth goes through cycles that are
much longer in duration than our human
perspective of time.
Assessing the Age of the Earth
Geologists placed relative dates on
exposed rock formations based on
similarities and differences in rock
composition and the preserved biota.
relative positions of these rock formations
Geologists later placed an absolute
dates on rock using radiometric dating
techniques to confirm relative ages.
Ages in
millions of
years
Today’s Geologic Date:
Recent Epoch
Quaternary Period
Cenozoic Era
Phanerozoic Eon
Fig. 17-1, p. 394
The Earth is currently experiencing an interglacial episode
CHAPTER SUMMARY
• We can view Earth as a system of interconnected components that interact and
affect one another. The principal subsystems of Earth are the atmosphere,
hydrosphere, biosphere, lithosphere, mantle, and core. Earth is considered a
dynamic planet that is continuously changing because of the interactions
among its various subsystems and cycles.
• Geology, the study of Earth, is divided into two broad areas: Physical geology is
the study of Earth materials as well as the processes that operate within and on
Earth’s surface; historical geology examines the origin and evolution of Earth,
its continents, oceans, atmosphere, and life.
• Geology is part of the human experience. We can find references to it in the
arts, music, and literature. A basic understanding of geology is also important
for dealing with the many environmental problems and issues facing society.
• Geologists engage in a variety of occupations, the main one being exploration
for mineral and energy resources. They are also becoming increasingly
involved in environmental issues and making shortand long-range predictions
of the potential dangers from such natural disasters as volcanic eruptions and
earthquakes.
CHAPTER SUMMARY
• About 4.6 billion years ago, the solar system formed from a rotating cloud of
interstellar matter. Eventually, as this cloud condensed, it collapsed under the
influence of gravity and flattened into a rotating disk. Within this rotating disk,
the Sun, planets, and moons formed from the turbulent eddies of nebular
gases and solids.
• Earth is differentiated into layers. The outermost layer is the crust, which is
divided into continental and oceanic portions. Below the crust is the solid
portion of the upper mantle. The crust and solid part of the upper mantle, or
lithosphere, overlie the asthenosphere, a zone that slowly flows. The
asthenosphere is underlain by the solid lower mantle. Earth’s core consists of
an outer liquid portion and an inner solid portion.
• The scientific method is an orderly, logical approach that involves gathering
and analyzing facts about a particular phenomenon, formulating hypotheses
to explain the phenomenon, testing the hypotheses, and finally proposing a
theory. A theory is a testable explanation for some natural phenomenon that
has a large body of supporting evidence.
• The lithosphere is broken into a series of plates that diverge, converge, and
slide sideways past one another.
CHAPTER SUMMARY
• Plate tectonic theory provides a unifying explanation for many geologic
features and events. The interaction between plates is responsible for
volcanic eruptions, earthquakes, the formation of mountain ranges and ocean
basins, and the recycling of rock material.
• The rock cycle illustrates the interactions among internal and external Earth
processes and shows how the three rock groups are interrelated.
• Igneous, sedimentary, and metamorphic rocks are the three major groups of
rocks. Igneous rocks result from the crystallization of magma or the
consolidation of volcanic ejecta. Sedimentary rocks are formed mostly by the
consolidation of rock fragments, precipitation of mineral matter from solution,
or compaction of plant or animal remains. Metamorphic rocks are produced
from other rocks, generally beneath Earth’s surface, by heat, pressure, and
chemically active fluids.
• Time sets geology apart from the other sciences, except astronomy, and an
appreciation of the immensity of geologic time is central to understanding
Earth’s evolution. The geologic time scale is the calendar geologists use to
date past events.
• The principle of uniformitarianism is basic to the interpretation of Earth
history. This principle holds that the laws of nature have been constant
through time and that the same processes that operate today have operated
throughout the past, though at different rates.