Describe the basic processes and timeline that led to the formation of Earth and its ocean and atmosphere
Earth formed about 4.6 billion years ago through the accretion of particles orbiting in our solar system. Earth was initially molten and layers only formed once planet began to cool. Density stratification allowed the least dense elements to escape to Earth's surface and atmosphere, while the denser elements sunk to form the internal layers of Earth, the mantle and core. The ocean and the atmosphere formed together as the planet cooled sometime between 4.4 and 3.8 billion years ago. The ocean formed as water vapor trapped in Earth's outer layers escaped to the surface via volcanic activity, a process called outgassing. This vapor cooled and condensed to form an ocean.
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A rock composed of fine-grained pyroclastic particles is called:
a) Tuff b) Pumice c) Scoria d) Rhyolite e) Obsidian
Most of the public health impacts from air pollution are the result of
A) acute exposure to a single pollutant. B) acute exposure to many pollutants. C) chronic exposure to a single pollutant. D) chronic exposure to many pollutants.
The poorest regions of China are generally:
A) in the northeast B) in the east C) in the south and west D) around cities on the eastern coast
At sea level, the pressure of the atmosphere is about ________ kg/cm2, or ________ ln/in2
A) 1.0; 14.7 B) 2.6; 9.4 C) 8.2; 3.3 D) 6.7; 19.9