Exam 1 Flashcards
geologic record is divided into 3 eons
The Archaean, The Proterozoic and the Phanerozoic
How long ago was earth formed
4.5 bya
Terrestrial planets (inner planets) Mercury, Venus, Earth and Mars
metallic cores (iron and nickel, surrounded by rock), High density, Little atmosphere
Jovian planets (outer planets) Jupiter, Saturn, Neptune, Uranus and Pluto)
Metallic cores (iron and nickel, surrounded by liquid helium), low density, lots of atmosphere, most have rings and numerous satellites
what information is used to calculate the age of the earth?
age of meteorites (should be the same age as planets)
why are meteorites used to calculate the age of the earth?
they are materials left over from formation of inner rocky planets when solar system formed
what chemicals are in the inner core
iron (94%) Nickel (6%)
what chemicals are in outer core
iron (85%), oxygen (5%), Sulfur (5%), Nickel (5%)
what chemicals are in the mantle
oxygen (44%), calcium (2.5%), magnesium (22.8%), silicon (21%), aluminum (2.4%), iron (6.3%)
Do s-waves pass through the core?
No, that’s how they know the core is liquid
Do p-waves pass through the core?
yes
premordial helium
there is no processes on earth capable of creating 3H. we find 3h in rocks and fluids thats how we know earth is still degassing. primordial helium emanates from the ground at sites of lava plumes like those found in hawaii
topography
defining form and shape
geomorphology
focuses on the evolution of topographic and bathymetric features
continental crust
20 to 60 km thick, made of granite, less dense, most is above sea level, light color, coarse
oceanic crust
only about 10 km thick, made of basalt, very dense, below sea level, dark color, fine texture
emergent coasts
where tectonic forces are pushing upwards (usually active continental margins). sea cliffs and marine terraces
submergent coasts
where sea level is rising faster than land and/or coastal areas are sinking
what type of coast are estuaries associated with
submergent coastlines formed when sea level rises and flood existing river valleys
continental margins
the submerged edge of continents they include: continental shelf, slope, rise and submarine canyons
they are influenced by tectonic uplift and subsidence.
they are areas of high sediment deposition from continents
what do active continental margins have
narrower shelf, deep sea trench, tend to be narrower (like west coast), may have high sediment accumulations but sediments go into deep trench
what do passive continental margins have
thick accumulations of sediments, wider shelf, a continental rise, tend to be wider (like east coast)
where are active margins location
around the pacific
where are passive margins located
around the Atlantic and parts of the Indian ocean