lecture 04: lithosphere and earth's history up to the quaternary period Flashcards
when did the big bang happen
~13.8 billion years before present (YBP)
when did our solar system and sun form?
~5 Ga (~9 Ga after the big bang)
how long ago did earth form
4.5 Ga
theia impact
theorized, mars sized object impaction forms the moon 4.5 Ga
lithosphere
solid outer part of earth including the crust and the upper part of the mantle
what periods are in the paleozoic era
cambrian, ordovician, silurian, devonian, carboniferous, permian
what periods are in the mesozoic era
triassic, jurassic, cretaceous
what are the eras
precambrian, paleozoic, mesozoic, cenozoic
what period are we in now
quaternary
what epoch are we in now
holocene
when did the earths continents start forming
~3 Ga
what is the canadian shield
large exposed area of igneous and metamorphic rock
how did the continents form
planet was hot and convection was vigorous in the mantle. rocks rose to the surface forming the lithosphere
cratons
floating pieces of the lithosphere that stopped growing around 2 Ga as earth was cooling
modern ear of plate tectonics
added new margins to the original cratons, expanding the continents
north american cratons
superior, slave, churchill, wyoming
mesozoic era
252-66 Ma
middle-life
began at the permian-triassic extinctino event 252 Ma and was the earth’s most severe extinction event
triassic period
252-201 Ma
recovery of extinction period, breakup of pangea, expansion of dinosaurs and gymnosperms
jurassic period
201-145 Ma
more tropical and humid, expansion of seas, dinosaurs begin to dominate, first true mammals evolve
cretaceous period
145-66 Ma
more expansion of seas, more seasonality, birds developing, volcanic eruptions affecting atmosphere, much of alberta’s bedrock deposits
sedimentary basin
thick area of the earth where the crust is underlain by a thick sequence of sedimentary rocks
what are the layers of rocks called
beds
what are the boundaries separating beds of rocks called
contacts
k-t boundary
point between creatceous and tertiary periods where large dinosaurs disappeared and the boundary in rock sediments had high concentrations of iridium
luis and walter alvarez
studied the boundary and determined the impactor based on iridium amounts spanned at least 10km in diameter
canadian rockies
formed mostly from sedimentary rock in the late paleozoic era and uplifted 185 Ma to 55 Ma
what do u-shaped valleys indicate on mountains
that they were shaped by glaciers
what percentage do mountains make up the earths surface
30%
