chapter 1 - understanding earth

four main earth elements

(90% ) iron, oxygen, silicon, magnesium

internal heat engine

(released radioactively) -heat drives motions in the mantle and core, supplying engery to melt rock, move continents, and lufe up moutains -heat energy was trapped in interior during Earth's violent origin and is released inside planet via radioactivity. -Drives mantle and crust movements, responsible for melting rock, moving continents, and lifting up mountains

oceanic crust

*- Ocean crust consists of basalt (mafic volcanic rock denser than granite).* - BOOK: rocks in the oceanic crust contain more iron and are denser than continental --7 km -density (3.0 g/cm3) -thick iron dense (sinks)

principle of uniformitarianism

*The assumption that the same natural laws and processes that operate in the universe now have always operated in the universe in the past and apply everywhere in the universe.* -First described by James Hutton later and expounded on by Charles Lyell.-"present is the key to the past" -geological processes we see today work in the same way throughout geologic time

continental crust

*consists of granite and granite-like rocks.* -40 km -denisty (2.8 g/cm3) -less dense, so can float on denser mantle -less dense than oceanic crust, so ride high

what is the scientific method?

*strives to eliminate bias and provide results that can be tested for reproducibility by other researchers.* gathering and analyzing facts, formulating hypotheses to explain the phenomenon, testing the hypotheses, and finally proposing a theory

why has Wiechert puzzled by the earths denisty? and what did he realize?

- the earth is made up of silicates, which have a less density -some iron-rich rocks that were brought up from volcanoes had high densities but only 3.5 -pressure squeezes rock, but not enough to significantly change the density -meteorites were rlly dense (8 g/cm3) -so came up with that in the earths past iron and nickel dropped inward to its center under gravity to create the CORE, which is surrounded by silicate rock and called the MANTLE -tested then hypothesis with seismometers -wiechert's hypothesis? The diff compositions of the Earth's layers are primarily the work of gravity

geologic record

-information preserved in rocks formed at various times throughout earths history. -use the geo record to compare things to current observations

what are the 3 components of the plate tectonic system?

-involves interactions among the lithosphere, asthenosphere and deep mantle -Convecting mantle and its overlying mosaic of lithospheric plates.

scientific model

-knowledge based on many hypothese and theories can be used to create a scientific model -A precise representation of how a natural process operates or behaves - combination of related ideas used to make predictions

James Hutton

-principle of uniformitarianism -"present is the key to the past" -geological processes we see today work in the same way throughout geologic time

climate system

-solar radiation (so external) -Includes all Earth system components that determine climate on global scale and how climate changes with time; atmospheric behavior and interactions between -hydrosphere, - cryosphere, -biosphere, and - atmosphere

seisometers (two types of waves)

-they test with seismic waves so we can look into the earth -compressional waves: expand and compress as they travel through solid, liquid or gas -shear: only pass through solids and move in a side to side motion

The first appearance of Homo sapiens on Earth occurred in

0.16MA

how old is the universe?

14 billions years old

Roughly when did most earth scientists accept plate tectonics as a theory?

1970

How old are the oldest rocks on the ocean floor?

200 million

The density of most rocks ranges from ___ to ___ g/cm3.

3:4

how old is the earth?

4.6 billion years old

earths denisty

5.5 g/cm3

Earth's atmosphere has been oxygen rich for approximately ________ of Earths history?

50%

Living organisms have been on Earth for _________ of Earth's history.

80%

what is a theory?

A tentative explanation based on collected data through experiments and observations. Supported if it explains new data or predicts the outcome of new experiments. -has survived repeated challenge and accumulated a substantial body of experimental support can be elevated to status of THEORY -conjecture, an opinion, a speculation, or a hypothesis -it can never be considered finally proved

the upper and lower mantle are separated by?

A transition zone where the rock density increases in a series of steps not caused by changes in chemical composition, but by changes in compactness due to increasing pressure with depth

Seismic waves

A vibration caused by an earthquake that is then measured to allow geologists to locate earthquakes and create pictures of the Earth's interior -make pics of inner workings (ultrasound)

Who proposed the theory of continental drift?

Alfred Wegener

climate system includes?

All earth system components that determine climate on a global scale & how it changes with time

what constitutes the earth system?

All parts of our planet & all their interactions, taken together Collection of open and interacting geosystems. -OPEN SYSTEM that exchanges energy and mass with surroundings, comprised of subsystems: climate, plate tectonic, and geodynamo

Which scientist was the first to suggest the existence of so-called "supercontinents"?

Austrian Eduard Suess

weather is governed primarily by?

Changes in solar energy input on seasonal and daily cycles clima Temperature, precipitation, cloud cover, and winds observed at particular locations and times on Earth's surface.

major leyers of the earth

Crust, mantle (upper, lower), outer core, inner core

how is the magentic field maintained

Geodynamic Forces In The Core Create Earth's Magnetic Field The magnetic field is thought to be created by the fluid dynamics in the outer core as it interacts with the solid inner core.

Where is one of the best places to study seafloor spreading on dry land?

Iceland

where do the forces that push/pull the plates originate from?

In the mantle's internal heat engine - drives the rise at boundaries where the plates separate, forming -types: internal and external

what are the 2 components of the geodynamo system?

Inner core, outer core the rapid motions/ electric currents that occur in the outer core which produce a strong magnetic field

Ninety percent of Earth is made up of which four elements?

Iron oxygen, silicon, magnesium

Stony meteorites are similar in composition to Earth's

Mantle

what makes up the bulk of earth

Mantle

What drives plate tectonics?

Mantle convection

The largest jump in desnsity within earth is at the?

Mantle core boundary

deep mantle

Mantle forms the main bulk of the solid earth. The deep mantle is solid & lies between the base of the asthenosphere to the core boundary extending from 400 km to 2,900 km deep. -Composed rocks of intermediate density, containing oxygen, magnesium, iron & silica

Which of the following plates contains only oceanic crust?

Nazca Plate

Which type of measurements initially led to determining the rate of plate movement with a high degree of accuracy?

Radio telescopes

what are geosystems?

Specialized subsystems that produce specific types of activity such as climate change or mountain building. -earth is lots of overlapping goesystems

what is the greenhouse effect?

Sun warms earth's surface; some heat is trapped by water vapor, carbon dioxide & other gases in the atmosphere - explains why earth's climate makes life possible

What ocean used to lie between Africa and Eurasia and was the ancestor to today's the Mediterranean Sea?

Tethys

earths climate is controlled by?

The balance b/t solar energy coming in and heat energy radiating out from within

what is the plate tectonic system?

The convecting mantle &

what is the plate tectonic theory?

The lithosphere is composed of rigid plates that diverge, converge, or slide sideways past one another as they move over the asthenosphere.

Lithosphere

The strong rigid outer shell of the Earth that includes the crust and the upper, rigid mantle. -extends to an average depth of 100 km under continents and forms the tectonic plates. • The lithosphere consist of rigid plates that move laterally over the mechanically weak (soft) asthenosphere, which is a zone of partial melting.

atmosphere

The thin layer of gases surrounding Earth. Nitrogen, oxygen, water vapor and carbon dioxide are major gases, while many minor gases are also present in trace amounts. BOOK: gaseous envelope extending from the earth's surface to an altitutude of about 100km

what is geodynamo?

The third global geosystem involving interactions that produce magnetic field deep inside the earth in its liquid outer core.

hydrosphere

The water on Earth, in all of its liquid manifestations: oceans, rivers, lakes and groundwater. Water vapor is considered to be an atmospheric component.

cryosphere

The water on Earth, in all solid forms including ice and glaciers. BOOK: polar ice caps, glaciers, other surface ice and snow

asthenosphere

The weak layer of soft but partially molten layer that comprises the upper part of the mantle (below the lithosphere) over which the tectonic plates slide. -300 km thick.

what are fossils

Traces of organizms preserved in the geologic record first fossil? Primitive bacteria 3.5 b years ago

what is a solid aggregate of one or more minerals, as well as non-crystalline matter, such as natural glass or organic material like coal?

a rock

what does the core consist of?

a small, solid inner region - a larger, liquid, outer portion - composed of iron and a small amount of nickel

what is the mantle divided into?

a solid LOWER mantle, a PARTIALLY MOLTEN asthenosphere that overall behaves plastically and flows slowly, and a solid UPPER mantle

what is a hypothesis?

a tentative explanation based on data collected through observations and experiments

Solar energy energizes which of the eathr's componants?

atmosphere, biosphere , hydrosphere

what is physical geology?

concerned with the materials and processes which compose and operate on the surface of, and within, Earth

what is historical geology?

concerned with the origin and evolution of Earth's continents, oceans, atmosphere, and life.

topography

earth surface disturbed by changes in the ground elevation (measured with respect to sea level)

the earths layers are primarily the work of what??

gravity

what are the 5 components of the climate system?

interactions among the atmosphere, hydrosphere, biosphere, cryosphere, lithosphere

The plate tectonic system is driven by?

internal heat

why is the outer core liquid and the inner core solid?

iron-alloys in the inner core are frozen due to presure, which is why the inner core is solid EVEN though it is hotter inner core is a solid metallic sphere suspended within the liquid outer core "a planet within a planet"

Which of the following relationships is CORRECT?

lithospheric = crust upper mantle

what do geologist's principle occupations include?

mineral and energy resource exploration, and predicting natural disasters

An island arc forms when there is __________ convergence.

ocean-ocean

geodesy

old science that studies the earths shape

what is the mantle primarily composed of?

peridotite (an igneous rock made of olivine)

what are meteorites?

pieces of material that originated in the formation of the Solar System

how are the rock cycle and plate tectonics related?

plate movement is the driving mechanism of the rock cycle. Plate interaction determines, to some extent, which of the three rock groups will form

What plate is subducting beneath southwestern Canada and the northwestern United States?

san de fuca plate

Geologic processes can take place of over times that last from

seconds to billions of years

devices used to detect earthquakes are called?

seismometers

external heat engine

solar energy, supplied to Earth's surface by sun. Energizes the atmosphere and oceans and is responsible for climate/weather (erosion shapes landscape and in turn influences climate)

Mid-ocean ridges are also referred to as?

spreading centers

Which of the following is a divergent plate boundary?

the Mid-Atlantic Ridge

what are metamorphic rocks formed from?

the alteration of other rocks BY heat, pressure, and chemically active fluids

what surrounds the lower mantle?

the asthenosphere

describe geology:

the branch of Earth science that studies all aspects of the planet: history, composition, internal structure, surface features - outdoor science, planetary science

what does the mantle surround?

the core

what makes up the lithosphere?

the crust and upper mantle (which forms the solid outer layers of the earth)

what is the crust?

the outermost layer

timing of geologic processes??

they take place over a tremendous range of scales in both space and time

what is the crust divided into?

thick continental crust and thin oceanic crust

Deep focus earthquakes are typically associated with which type of boundary?

transform

What type of plate boundary is parallel to the direction of plate movement?

transform plate boundary

Geologist James Hutton advanced the principle of

uniformitarianism

biosphere

• The overall ecosystem encompassing all life on Earth. The sum total of all the biomes and smaller ecosystems, which ultimately are all interconnected and interdependent through global processes, such as the hydrologic cycle and atmosphere cycles. BOOK: all organic matter related to life near surface energized by solar radiation • The biosphere also extends into the crust (lithosphere) of Earth to encompass extensive subsurface microbial systems. active component of the climate system's control