NATURE OF OUR PLANET Flashcards
earth formation
- 4.5Bya from a cloud of gas and dust
- small particles collided and stuck together to form larger bodies, which collided and merged to form a protoplanet
- earths interior differentiated into layers as heavier materials san and lighter materials rose
- exterior rocks containing water crashed into earth, which evaporated creating the atmosphere
- it cooled, and due to precipitation, oceans were formed
age of the earth
- 4.6by
- was determined by putting together 3 dating measures
relative dating
- the study of sedimentary and volcanic rocks used to determine their relative age
- the rock record is used, and geological events are dermtermined
- it is not based on numbers, but periods
absolute dating
- method to determine the number of years that have elapsed since an event occurred
- it provides a certain age
- based on radioactive decay. which is natural to elements because of their isotopes which release radiation in attempts of becoming more stable
half life
- elements decay at a constant rate
- scientists know the time of a half life of an isotope, making it possible to measure how much time has passed by measuring the amount of parent and daughter isotopes
- the ratio between daughter isotopes and parent isotopes indicate how much time has passed since the element was created
paleomagnetism
using radioactive dates and measurements of the ancient magnetic polarity in volcanic sedimentary rocks
- geologists have been able to determine precisely when magnetic reversals occur
- black: normal polarity white: reversed polarity
seismic waves
have been used to determine the layers inside earth
primary waves
- propagates through the interior of the earth in all directions
- longitudinal , which means that the particles of the material move in the same direction in which the wave is propagating
- they travel through both solids and liquids
- fastest seismic wave
secondary wave
- transverse waves which means that the particles of the material vibrate perpendicular to the direction of propagation
- they can only travel through solids
- second fastest seismic waves, which travel at 60% the speed of p waves
earth layers
- s waves are not detected after certain distances, which suggests that there is a liquid layer in earths core
- the change in p waves pattern suggest a change of density, meaning there is also a solid inner core,and explaining the shadow zone
crust
- outermost layer of the earths surface
- continental crust is thicker and less dense, it is what makes up what we stand on
- oceanic crust is thinner and denser, and found in ocean floors
mantel
- layer between the crust and the core, makes up the largest portion of earths volume
- can be divided into several parts
upper mantel
mostly solid, but some malleable regions are affected by tectonic activity
lithosphere
- includes the crust and upper mantel
- rigid layer that is broken into large plates that move and interact
- responsible for the formation of contingents, and responsible for the most seismic activity
lower mantel
a solid later of rock, but due to the high pressures and temperatures, it slowly flows
asthenosphere
- under the lithosphere
- soft later which plays an important role in the movement of tectonic plates, by providing a weak later for the lithosphere to slide and move
outer core
- a layer of liquid metal that surrounds the inner core
- it is in a constant state of motion due to the heat generated by radial active elements
- its motion generates the magnetic field
inner core
solid ball of metal located at the center of earth
continental drift theory
- proposed by alfred wegner
- suggested that the continents were once a single landmass known as pangea, which began to drifting apart over time
- fit of the continents
- rock formations and fossils are found on continents that are now separated
tectonic plate theory
lithosphere was broken up into several large plates that move relative to each other over time, causing geological events
movement tectonic plates
its main cause are convection currents, and the heat that rises and causes a fracture in the crust
divergent boundaries
where plates move away from each other, allowing magma to rise up and create new crust
convergent boundaries
- where plates move towards each other, and one plate is forces beneath the other
- this leads to the formation of mountains, volcanic, and ocean trenches
transform boundereies
when plates slide past each other, creating faults and earthquakes
atmosphere 1
- composed of hydrogen and helium
- it didn’t last very long, as light gases move quickly when heated, causing them to escape
atmosphere 2
the volcanoes released many gases, but there was no free oxygen
atmosphere 3
there was less carbon dioxide present, instead it was replaced by oxygen which is needed for life
oxygen on earth
- it was not present until 2.6bya, and it has increased since
- this date was derived from a FeO layer in sedimentary rocks. iron was element all around earth because of weathering and hydrothermal vents, but since there was no oxygen in the planet, iron could travel through water, but with the presence of oxygen it made a covalent bond, making it precipitate due to its density
presence of oxygen
it is only present in our atmosphere through photosynthesis that took place in some bacteria
equilibrium
- continuous loop between photosynthesis’s and cellular respiration that ensures that all O2 produce is consumed
- O2 levels only increased when O2 production exceeded consumption, which happened when geological activity burried the organic material needed for cellular respiration
- higher levels of O2 allows multicellular life to emerge because there is more energy present
components of the atmosphere
nitrogen, oxygen, argon, carbon dioxide, helium, methane, krypton, hydrogen
troposphere
- lowest part of the atmosphere
- contains weather (clouds rain and snow) and it contains most of the air in the atmosphere
- it is divided in the tropopause and the boundery layer at its lowest
- temperature is lower than that of the stratosphere due to less height and pressure
stratosphere
- above the tropopause
- contains most of the ozone
- it stops UV rays and other radiation form, entering the planet
- temperature is higher than the troposphere due to the increase in UV rays and height
mesosphere
- temperature decreases with height, due to decreasing absorption of solar radiation
- coldest atmosphere in layer surrounding earth
- reaches a minimum of -90c getting to the upper stage
thermosphere
- temperature increases with hight because of the energetic UV and X rays from the sun
- temperature depends if it is day, night or seasons (ions and electrons also change due to the same characteristics)
exosphere
- represents the outermost layer of the atmosphere above the globe
- contains hydrogen and oxygen atoms
- less dense layer (difficult collision)
- trajectory is ballistic because of gravity cases that can escape and go to space
magnetosphere
- there is an interaction between solar winds and earths magnetic field
- contains protons and electrons
- partials spiral in the magnetic field
pressure in the atmosphere
as the altitude increases, pressure decreases
ozone layer
- region of high ozone (O3) concentration in the stratosphere
- it acts as an invisible shield that protects earth from harmful ultraviolet radiation emitted form the sun
UV-C
light is completely absorbed by the ozone layer
UV-B
98% is absorbed by the ozone layer
UV-A
along with visible light, most of it reaches the surface
ozone equilibrium
- constantly being created and destroyed
- O3 molecule absorbes UV and comes apart into O2 AND O
- the atoms interact with other O molecules to reform the ozone molecule
ozone threat
caused bu the accumulation of chloroflutoncarbons that depleate the ozone layer
CFC
reaches the stratosphere where it absorbes UV radiation, causing it to decompose and release its chlorine atoms, which destroyed 100k ozone molecules
ozone hole
- caused by too many of the chlorine reactions that disrupt the balance
- the montreal protocol was a global agreement to protect earths ozone layer by phasing out the production of CFC
weather
what conditions of the atmosphere are during a short period of time
climate
- how the atmosphere behaves over relatively long periods of time
- it is complex and dynamic, and influenced by the amount of solar radiation hitting earth and the composition of the atmosphere
greenhouse effect
- affects the temperature through chemical composition and solar radiation
- earth receives energy from the sun in UV rays and some of this energy is absorbed by the surface, which warms up and emits heat back into space in infrared red radiation, however some of this energy is absorbed by gases in the atmosphere that trap the heat, warming up the atmosphere
formanifera
- shell made out of calcium carbonate
- helps scientists reconstruct past climates
- the low temperatures favor the metabolism of CaCo3 of O18
- the ratio between O18 and O16 are inversely proportionate to temperature, so by measuring the ratio, scientists are able to date back and reconstruct temperatures
CO2 and temperature
- it is a causation relationship
- CO2 concentration is linked to the fluctuations in the atmosphere in temperature
solar energy
- one of the factors that drives more rapid and smaller scale variations
- cyclical pattern of ice ages
- small changed in earths orbit around the sun affect the amount of solar energy striking the planet
- found by Milutin Mailankovitch
