Transcript PowerPoint - Text Version

The Beginning of the Beginning
• At the beginning of the universe,
explosion separated gases into
subatomic particles
• It cooled as ions, forming
hydrogen atoms, and then fusing
to cause stars
• Stars exploded, causing planets
and asteroids to form from the
remains
• Galaxies of star systems orbits
due to the gravitational force at
the center
• Collisions of galaxies formed
even bigger galaxies, such as
the Milky Way
• One of the stars explode and
matter cools into planets and
the asteroid belt
• Smaller planets collide
to form bigger planets
which are now known
to day
• Formed the nine
planets of the solar
system
The Earth
• Earth is the only planet with visible water
and an atmosphere with a fair supply of
oxygen, therefore possible for life
Earth is made of several layers:
• Inner core – solid iron and nickel
• Outer core – liquid iron and nickel; spinning
around the inner core to form an
electromagnetic field
• Mantle – liquid-like molten metal
• Crust – consisting of 15 plates “floating” on the
mantle
• The Earth is 4.5 billion years old
• Timeline of the Earth is separated into 3 eras:
Cenozoic, Mesozoic, Paleozoic
• Paleozoic: Precambrian,
Cambrian, Ordovician, Silurian,
Devonian, Mississippian,
Pennsylvanian, and Permian
• Mesozoic: Triassic, Jurassic,
Cretaceous
• Cenozoic: Tertiary, Quaternary
Paleozoic (Part I)
• “Dark Ages” covers the time from formation of Earth
to approximately 590 million years ago
• No life forms existed for the beginning of Precambrian
• Many theories were made, however none were able to
support their theory
• First actual “animals” were
trilobite, seasnail, and
giant water scorpions
(Precambrian, Cambrian,
Ordovician, Silurian)
• First plants were algae and
graptolites
Paleozoic (Part II)
• Lungfish and Mollusk were introduced during
Devonian
• Land amphibians introduced during Pennsylvanian
• Plants evolved
into seedbearing trees,
corals, and early
land trees
• During Permian,
reptiles and
early sharks
appeared
Mesozoic
• Mesozoic is also
known as the “Age of
the Reptiles”
• Triassic period (248
million years ago) filled
with early dinosaurs
and sea urchins
• Jurassic period is dominated by dinosaurs,
modern trees, and… birds with teeth!
• In Cretaceous period, ammonite and flowering
plants began to appear
Cenozoic
• Cenozoic period began when the dinosaurs were gone
• Nobody knows what happened, but theory says that a
BIG meteorite crashed onto the earth and the dust
blocked out the sunlight and therefore reptiles, such
as dinosaurs, could not survive
• In the Tertiary period,
(65 million years ago)
oysters, marsupials,
primate, and seabirds
appeared
• Introduced the wooly
mammoth, the deer,
and humanity in
Quaternary
What are Fossils?
• Formerly, All minerals were called fossils
• Remains or traces of an organism of a past
geological age, such as a skeleton or leaf
imprint embedded and preserved in the
Earth’s crust
Animal Fossils
Traces
Footprints or a
marking left by the
creature that is
preserved in rocks
Remains
Bones and teeth
that remained
when its skin and
flesh are eaten
away by bacteria
The Importance of Fossils
• Key to unlocking the many mysteries of
the past
• Evidence of the existence of these
ancient magnificent creatures
• Also evidence for theories of how the
Earth looked like millions of years ago
• Skeleton can allow scientists to know
how they look like
• Teeth and droppings allows scientists
to understand the creature’s diet
Ways to Form Fossils
Tar Pit – oil deposits heated by plate
movements becomes a thick, gooey
soup asphalt, which becomes pools of
tar when surfaced. Animals can get
stuck in the tar and dies
Ice and Glaciers – during the last ice
age, some bigger animals, such as
mammoths, wooly rhinoceros, and
bison are trapped in the ice and
frozen.
Ocean Fossils – When an animal dies,
its body decays from bacteria, leaving
behind a shell. The shell sinks into the
sand at the bottom and over time,
sediments covers it and becomes rocks
Land Fossils – When an animal dies, its
remains are left, and over time, sand and
other sediments covers the remains and
form sedimentary rocks, therefore
fossilizing it. Over long periods of time,
the pressure from rocks above causes it to
become compressed
Volcanoes – Some trees near
volcanoes may be preserved since
the acidic environment can kill
the bacteria and also acid seeps
into the piece of wood and causes
it to become crystallized inside
Tree Sap – Ambers are considered
as fossils, even though it is not a
rock. Ambers are formed when
tree sap hardens over time. Many
of them have animals or plants
stuck in them and therefore are
preserved
Examples of Fossils
Petrified Wood
Dried Petrified Wood
Opalized Wood
Petrified Charcoal
Amber
Trilobite
Planorbis
Neptunia
Torritella
Dinosaur Eggs
Dinosaur Dung
Lycoptera
Relative Time and Absolute Time
Chronostratic Time – related to other events taking place
Chronometric Time – time with a number and a
measurement (quantity)
Relative timescale based on
four principles:
Absolute time scale
based on two
• Different types of rocks in
principles:
different locations
• Law of horizontality, law of
• A function of the rate
lateral continuity, law of
of change
superposition
• a quantity that the
• Law of cross cutting
rate function is based on
relation
• Law of faunal succession
Growth Rings on Trees
•Found in the trunk and branches
•One ring is grown yearly
• Rings on branch plus number of
years it took for the years for the
trees to grow the branch equals to
the tree’s age
• Distance between growth rings may
reflect on the environment
Growth Rings on Aquatic Animals
• Holocene shells have growth rings on the
outside and inside of its shell
• Growth rings are extremely crowded on
the outside and marks from severe storms
make dating difficult
• Growth rings on the inside of the
shell are easier to count since they
are made up of dark and light
bands
• Growth rings are also found on
corals and fishes
Varves in Geographic Formation
• 356 layers of stromatolites (found
in fossils) are produced by
cyanobacteria in one year
• Tidal rhythmites are left behind
from tides, caused by lunar
movement
• Stalactites’ length increases at a
constant rate every year
• Bands develop on anhydrites
every season
• Algae remains leave varves on
the lake bottom
The Atom
• All matter is made of tiny building
blocks called subatomic particles
• They include the proton, electron and
neutron, and form atoms
• Different elements have different
amounts of protons, neutrons
and electrons
• Isotopes are elements with
different number of neutrons
Isotopes and Radiation
• Some isotopes are unstable, so unstable
that, at random, protons, neutrons and
electrons separate from the isotope,
called radiation
• Can either shed nucleus of helium atom
(alpha decay), a neutron (beta decay), or
energy (gamma decay)
• Any element that is radioactive can be
used, but those with long half lives work
better
• Carbon 14 is used to date anything from
50,000 years ago, while uranium 238 can
be used to date things in billions of years
Half-Lives
• Individual radioactive atoms shed particles at random, and can’t
be predicted
• But groups of atoms shed particles at steady rate
• As particles continue to radiate out, the atoms turn into lighter
atoms called daughter particles (uranium turns into radon,
radon decays into polonium, etc.)
• The time it takes for half of all of mass of atoms to radiate into
lighter atoms is its half-life
History of Radioactive Dating
• First to discover radiation was Henri Becquerel, in 1896
• He and Ernest Rutherford first used radiation to date rocks in
1907
• The idea was further implemented after WWII, when radiation
was used for nuclear testing
• As measurements of both decay
and half lives improved in the
1950s, measurements became
more accurate
• Became a way to test everything
from rocks to fossils, and let
archeologists and geologists see
into the past
Tools and Processes
• Many radioactive materials exist naturally in
materials: potassium is usually found in lower
sedimentary rocks, while uranium is found in
• Mass spectrometer, Geiger counter are used to
measure the level of radioactivity
• Number of particles being emitted is
compared to half-life curve to determine
how old something is
• Also can tell by number of daughter
atoms, such as seeing how many
uranium atoms have turned into radon
• Another method involves spontaneous
fission and the radioactive tracks it
produces
ERROR
• Unfortunately, all naturally occurring rocks are subject
to contamination, so dating can be inaccurate
• Problems with scientific instruments: as tools get
better, so do results (in 1950, avg. result had 25%
error rate, modern tests have 5% error rate)
• Always strange results, like a Rb-Sr dating
giving 34 billion years
Plate Tectonics
• Alfred Wagener suggest that 200
million years ago, all continents were
together, called Pangaea
• However, his theory was ignored until
the 1960s
Evidence:
• Plant and animals which would not
have survived in the sub zeros found
in Antarctica
• Fossil of dinosaurs found in two
places across the Atlantic Ocean
• Realize Earth’s surface is not one big
piece
• Many smaller pieces called tectonic
or lithospheric plates, moved by the
slow convection currents in the upper
mantle
Rocks in mantle is very hot
Heated rocks tends to rise,
when some cooler rock
moves in to take its place
Forms convection current
Pangaea
• Shores of the continents fit together like
a jigsaw puzzle, as Wegener also did
• Pangaea means “all the Earth” in Greek
• Existed in the late Carboniferous times
• Formed from three smaller continents,
which later became two: Laurasia,and
Gondwana
Pangaea is split into two parts, Northern Pangaea and Southern
Pangaea, called Laurasia and Gondwana respectively
Laurasia = North America + Eurasia
(Europe)
Gondwana = South America + Africa +
Australia + Antarctica + Asia
Mid-Ocean Ridge
• Example: Mid-Atlantic Ridge
• A rift valley runs down middle,
meaning separation
• Along the valley, molten rocks
flows out
• Forms with two plate moves
apart, causing molten rocks to
rise
• Atlantic Ocean is getting bigger
as the sea floor spreads
Trenches
• There are two types of plates, oceanic
and continental
• Oceanic plate is heavier than continental
plate
• Oceanic plate slides under the
continental plate
• Ocean floor is pulled under by the plate
• Forming the lowest parts of the ocean
floor, including the Mariana's Trench
Mountains
• Two continental plates of similar
density collides with each other, one
would not slide under
• Crash into each other, like two cars
running at full speed at each other
• Cause bottom half of the plates
to go down and top half to ruse
up into sharp mountains
• One great example of this is the
Himalayas
Weathering
• Chemicals in rocks are unstable in
damp, oxygen-rich atmosphere
• Used to the hot and high pressure
surroundings
• This reaction is called weathering
• Temperature also cause weathering
• Sun heats up rocks during the day,
and the cold of the night causes the
rocks to crack
Erosion
• Erosion is process where material in
solution and loose rock fragments are
removed from the original location and
transported to another place
Examples of erosions:
• Ice
• Wind
• Water (waves and rain)