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Earth and its Wonders
Transcript of Earth and its Wonders
Earth's Early Formation
one hundred billion years ago
entire solar system
including the Earth and the Sun were nothing but a big cloud of freezing fragments. Then each fragment started to get attracted to each other and soon were
forming a huge spinning like disk
. As it was spinning the disks started to become into rings and because of the speed the rings were going, it made them fiery white-hot. The
center of the disk became the sun
, and the fragments in the outer rings turned into huge balls of fiery gas and molten-liquid that cooled and condensed to take a solid form.
Four or five billion years ago
turned into the planets that we now know today
as Earth, Mars, Venus, and the other outer planets.
The first period in time for Earth was known as the "Hadean" period, it was named after the greek god Hades, god of the underworld. The reason it was named this was because it referred to the condition of Earth at this certain time. During this time, Earth was being hit continuously by meteorites. Volcanoes were erupting constantly due to the large heat flow and geothermal gradient. The Primordial Atmosphere was produced by the out gassing and volcanic activity.
How the Moon was Formed
The theory that is the most widely accepted is that a
Mars-sized object collided with earth
, billions of years ago. This impact
reversed Earth's evolution and turned it back into a ball of molten rock and also ejected material into orbit.
Most of the material crashed back into the Earth, but
some collected together from mutual gravity to form the Moon we have today.
The first present-day idea about the formation of the Moon was called the "fission theory" and it was discovered by George Darwin, son of Charles Darwin. His theory was that the moon must of broken off from Earth when the Earth was still a rapidly rotating ball of molten rock. His theory lasted from the 1800s right up until the space age.
What is the K-T boundary?
"K" is the traditional abbreviation for the Cretaceous period
"T" is the abbreviation for the Tertiary period.
So the K-T boundary is the point in between the Cretaceous and Tertiary periods.
The K-T Boundary is a thin dark line found in layers of sediment around the world; evidence that something disastrous must've happened to the planet 65 million years ago.
Geologists believed that this took place about 65.5 million years ago. Physicists Luis Alvarez and geologist Walter Alvarez studied the K-T Boundary around the world and found that iridium was in higher amounts around the K-T Boundary than anywhere else. It was between 30-130 times the amount of iridium you would expect. When they compared the concentrations of iridium in the K-T boundary, they found it matched the same amount found in meteorites. The researchers were able to estimate the exact kind of asteroid that caused the impact to throw up such a consistent layer of debris around the entire planet.
Vredefort Crater - The largest and oldest know impact crater.
It is approximately 250 kilometers in diameter and is thought to to be about two billion years old and it's located in South Africa.
Manicouagan Crater - fifth largest known impact crater
and created about 212 million years ago. Now, it's an ice-covered lake about 70 km across. The rock reveals clear signs of having been melted and altered by a violent collision. The original rim of the crater, but is now thinned out, is thought to have had a diameter of about 100 km.
Chicxulub Crater - Third largest
and lies mostly underwater and buried underneath the Yucatán Peninsula in Mexico. 170km (105 miles) in diameter. It most likely caused the
extinction of dinosaurs
because of the impact it had on the entire world basically causing a domino effect with tsunamis, earthquakes and volcanic eruptions, and the inability of green life to grow.
Sea Floor Spreading
In 1915, Alfred Wegener, German geologist and meteorologist, proposed the first theory of continental drift.
His theory stated that there was once a huge supercontinent, named Pangaea. 'Pan' - all
'Gaea' - earth.
Wegener suggested Earth's crust slowly drifted above a liquid core. The findings of fossils on the coasts of continents supports and gives credence to the theories of continental drift and plate tectonics.
Seafloor spreading happens when the
magma from the mantle makes its way upward to the surface
. As the magma works its way to the sea floor the
heat melts away the old sea floor and then it cools forming the new seafloor
Plate Tectonics are huge chunks of rock that is made up of both continental and oceanic crust. They are always moving and shifting, and cause earthquakes and volcanic eruptions.
The Earth's crust is not joined but is broken into what is called Plate tectonics.
The plates "float" on top of the mantle.
Magnetic reversals happen when the earth's magnetic field is reversed.
The North and South pole switch, and compasses instead of always pointing north would always point south.
It usually happenes every 1 million years.
This is a cause of the aurora lights.
A Divergent Boundary is when two plates move away from each other. They cause ridges and volcanic islands such as the Red Sea Lift.
Volcanic islands are created when molten lava can seep up through the crack to form.
The same formation is made with mid-oceanic ridges. Except they are underwater and create mountains.