Lecture 9 Planet Earth 2

How is the existence of Earth's unique atmosphere explained?

the oxygen in Earth's atmosphere is a result of early life on Earth

Which major atmospheric component is chiefly a product of life processes?

oxygen

Why does the Earth have abundant liquid water at its surface whereas Mars and Venus have none?

Venus is too close to the Sun so is too hot for liquid water, and Earth is in the habitat zone where liquid water is stable

What two major geologic processes work in opposition to each other to build up and wear down the landscape on the Earth?

Tectonic processes and erosional processes

Which geologic activities are influenced by plate tectonics?

Earthquakes, Mountain formation, and Volcano formation.

New continental crust is formed on the Earth:

in places where the mantle is down-welling and melting occurs creating new crust at subduction zones

New ocean crust is formed on the Earth:

in places where the mantle is upwelling and melting occurs creating new crust at mid-ocean ridges

True or False: Subduction of higher density oceanic plates under the continents not only creates deep trenches but also chains of volcanoes.

True

The earthquakes that occur in California generally occur along a:

transform fault

The extremely deep ocean Marianas Trench is a result of:

subduction

The slowly increasing distance between South America and Africa is due to:

seafloor spreading

True or false: Trenches are areas where the denser oceanic plates are subducted beneath the leading edges of lighter continental ones.

True

What drives the movement of tectonic plates on Earth?

Convection currents in the mantle

True or False: In the geologic past (approximately 250 million years ago), most of the landmass on Earth was concentrated in a single, large continent.

True

True or False: The energy for plate tectonics comes primarily from radioactive decay in the Earth's interior.

True

Rocks are age dated by geologists by measuring:

the products of radioactive decay in them

The Earth is estimated by astronomers to have formed:

between 4.5 and 4.6 billion years ago

The oldest minerals found on the Earth are age dated at:

4.4 billion years old

The formation and early geological history of the Earth can be broken into four stages.  What are these in order from first to last?

accretion, differentiation, condensation of water, continued differentiation from plate tectonic processes.