Unit 1 Exam Flashcards
Scientific Basics, Geologic Dating and Time Scale, Earths Structure, Plate Tectonics
Hypothesis
(Scientific basics)
possible explanations for our observations
theory
(Scientific basics)
well tested and widely accepted view that the scientific community generally agrees upon
scientific methods
(Scientific basics)
careful observation, construct hypothesis, test hypothesis
basic assumptions
(Scientific basics)
-the world is understandable
-scientific ideas are subject to change
-scientific knowledge is durable
-science cannot provide complete answers to all questions
original horizontally
(relative dating)
rock layers typically form a nearly horizontal position
superposition
(relative dating)
rock layers become younger from bottom to top
lateral continuity
(relative dating)
rock layers are assumed to have originally extended laterally in all direction unless they are observed to pinch out or terminate
cross cutting relationship
(relative dating)
any geologic feature that cuts across another the younger of the two layers(faults)
inclusion
(relative dating)
where fragments of one rock type is contained within rocks of another type, rock included is older
oldest to youngest
(relative dating)
EGLCHMDJANKBF
numeric dating
geologic clock, occurs at a constant rate, radioactive decay
radioactive decay
(numeric dating)
measuring the quantity of unstable atoms left in a rock and compare into the quantity of stable daughter atoms in the rock
phanerozoic
(geologic time scale)
-eon
-visible life
-hard bodied fossils
cenozoic
(geologic time scale)
-era
-recent life
-mammals
mesozoic
(geologic time scale)
-era
-middle life
-reptiles and dinosaurs
paleozoic
(geologic time scale)
-era
-ancient life
-intervertebral, fish, amphibians
Jurassic
(geologic time scale)
-period
-Mesozoic era
Cambrian
(geologic time scale)
-period
-Paleozoic era
how do we know what is inside the earth
(earths structure)
ultrasonography
-we measure earthquake waves, which have a low frequency but a lot of energy
inner core
(earths structure)
composed of iron
high density
high pressure
outer core
(earths structure)
high density
high pressure
liquid
mantle
(earths structure)
composed of iron rich silicate rocks
solid but able to flow over long timescales
astheosphere
(earths structure)
relatively weak and plastic zone
upper mantle
flows with time
lithosphere
(earths structure)
cool and rigid outer surface of the earth
uppermost mantle and crust
crust
(earths structure)
oceanic and continental
oceanic
(earths structure)
thinner, basaltic, more dense, relatively young
continental
(earths structure)
thicker, granite, less dense, can be very old
igneous rock
(rock cycle)
rock formed by the cooling and solidifying of liquid rock(magma) often formed by layer deposits
intrusive
(rock cycle)
form when magma cools slowly before it reaches the earths surface
eg granite
extrusive
(rock cycle)
forms when magma cools rapidly after it reaches the earths surface
eg basalt
sedimentary
(rock cycle)
formed by compactions and cementation of sediment typically form well layered deposits
eg limestone and sandstone
metamorphic
(rock cycle)
form from the alteration of preexisting rocks caused by increases in temp and pressure
eg gneiss
evidence of continental drift
-glacial ice
petrified wood
-glossopteris
-mesosaur
-boundaries of continents
-ancient climate patterns
-plant and animal ranges work
-ancient environments at right altitude
-similar rock types
-mountain belt ranges
mid ocean ridges
(sea floor spreading)
discovered in1872
an interconnect system of mostly underwater mountains on the seafloor, areas of recent or active volcanism
paleomagnetism
(sea floor spreading)
earths magnetic flow is produced by the flow of iron in the outer core, when igneous rock cools, some minerals pressure a signature of the original magnetic orientation at the time formed, can be read by sensors
study of earths sock shows that the earths magnetic field changes and reverses itself, takes thousands of years
tectonic plates
(plate motion)
a section of lithosphere (solid rock) commonly composed of both oceanic and continental crust, something is either being created or destroyed
relative motion
(plate motion)
measured relative to another tectonic plate (which is also moving)
absolute motion
(plate motion)
measured relative to a fixed reference point measured relative to a gps, relative to mantle hotspot
divergent
(plate motion)
plates moving apart from one another
convergent
(plate motion)
subduction, destructive, trench, volcanic activity
ocean ocean-marinas trench
ocean continent-Cascadia subduction zone
continent continent-mountains mount Everest
transform
(plate motion)
plates slide past each other
-creates earthquakes
-San Andrea’s fault
Wilson cycle
the cycle opening and closing of ocean basins as result of plate tectonics, results in the formation of super continents like Pangea about every 250 million years
mantle convection
(why plates move)
the mantle undergoes convection.
Convection is the movement of a substance according to the temperature of it. There are convection currents that carry heat from interior to the surface. The mantle is solid, but it can slowly move
slab pull
slab pull results from the sinking of a cold, dense slab of oceanic lithosphere and is the major driving force of plate motion
ridge push
ridge push is a gravity driven force that results from the elevated position of the ridge
