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20 Cards in this Set

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The _____ hypothesis states that the extinction of the dinosaurs was facilitated by a large _____ hitting Earth.
Alvarez, asteroid
A very accurate way to date living and non-living material using the predicted decary of certain elements is called _____ ______.
radiometric dating
The element _____ is often used for dating very old objects like the Earth, because it has a half-life of over 4.5 billion years.
uranium 238
The _________ is a part of the Earth's history when the planet was constantly bombarded with meteors and the surfce was liquid rock.
magma ocean
The _____ catastrophe occurred when the heavy elements sunk to the core of earth Earth.
iron
The magnetic field of Earth protects us against the _____ ____ which in radiation given off by our sun.
solar wind
The collision between Earth and a Mars sized planetoid created our _____.
moon
Two sources of the water on our planet are likely from _____ and _____
volcanoes, comets
Early life on Earth is hypothesized to be similar to life surrounding _____ in the deep oceans, where energy from hydrogen sulfide is used.
hydrothermal vents
The amount of oxygen in our current atmosphere is a result of billions of years of photosynthesis by _____ _____.
cynanobacteria
Evidence suggests that Earth and the _____ _____ were formed at the same time.
solar system
In radiometric dating scientists determine the amount of time required for _____ of the radiometric element to be converted into product.
1/2
_____ has the 1/2 life of 5703 years, which makes it suitable to date ____ samples.
young
Earth's liquid iron core flows and rotates gave rise to the _____ ____, which protects us from solar winds.
magnetic field
The first life on Earth lived in a very hostile environment, where bacteria survived only deep below the surface by extracting chemical energy from _____ _____.
hydrogen sultide
The cooling of the Earth's crust occurred _____ in the Earth's formation.
early
The atmosphere on Earth reached ____ oxygen about 560 million years ago.
21%
Briefly discuss 3 major events that took place before the development of life on Earth. For each event, give some details about what took place and any ramifications for life.
Iron catastrophe: The surface temperature of the early Earth reached very high temperatures from meteroid and asteroid bombardment and the radioactive decay of rocks. The surface of the Earth was filled with magma, and the heavy elements, such as iron, sank in the magma ocean to form the iron core of the Earth. This liquid iron core flows and rotates to generate the magnetic field that forms the north and south poles. Without this magnetic field, life would not be possible on Earth. This magnetic field acts as a shield to deflect the solar wind, protecting life from large doses of radiation.

Moon formation: The hypothesized formation of the moon states that a collision between a Mars-sized planet and Earth resulted in the formation of our moon. The impact of the collision was so large as to cause the axis of the Earth to tilt, causing the seasons on our planet. This collision is of obvious importance to Earth's climates and seasons and to the diversity of life that exists due to these seasonal variations.

Ocean formation: All the water on the planet formed after the planet cooled. The water came from two likely sources, Earth's volcanoes and comets. Volcanoes produce steam (water vapor) when they erupt. When the Earth was young, it was regularly bombarded by comets. The ice in the comet's tails would have melted upon contact with the Earth and could have contributed significantly to Earth's liquid environment.
Describe where the oxygen came from in our atmosphere and give 2 pieces of evidence for this process. How long did this process take?
By producing oxygen as a byproduct of photosynthesis, early bacteria caused a buildup of oxygen in the atmosphere, which allowed for the evolution of complex plants and animals. The modern day equivalents of these ancient life forms are the blue-green bacteria or cynanobacteria.

The photosynthetic microorganisms coated the surface of rocks in shallow bays, and they secreted a layer of sticky substance to use as protection against ultraviolet radiation. When sediments infiltrted into the layer, the microorganisms migrated to the surface. As this process occurred over hundreds of years, rock-like structures, known as stromatolites, were formed. These stomatolites can be found as fossils, suggesting they were responsible for the oxygenation of the atmosphere.

Iron oxide (or iron ore) which is mined today for steel production, is a byproduct of the oxygenation of the planet. It took about 1.5 billion years of continuing accumulation of atmoshperic oxygen to reach the current atmosphere oxygen concentration of 21%
When the Apollo astronauts brought back moon rock samples they were suprised to find that the composition was very similar to the rock found on Earth. Describe the hypothesis that the scientists come up with to explain how the moon was formed, discuss its importance to the formation of climate and seasons, and discuss why the moon rocks were similar in composition to Earth's.
Hypothesis: Moon was formed by a collision between early Earth and another small planet. This collision destroyed the other planet and removed a significnt proportion of Earth. The debris that was strewn into space eventually coalesced and formed the moon.

The force of the impact caused the Earth's axis to be tilted 23 degrees. This tilt gives rise to the seasons and climate found on Earth.

Since some of the debris were of Earth's origin that is not suprising that the composition of the rocks on the moon are very similar to that of Earth's.