exam 1 Flashcards
radius of the earth
4000 miles
circumference of the earth
2500 miles
revolution
1 year, noncircular elliptical orbit
distance from earth to sun
93 million miles
phase of revolution where the earth is farther away from the sun
aphelion, 93 million miles
phase of revolution where the earth is closer to the sun
perihelion 91 million miles
amount of years it takes for the orbit of revolution to rotate 360 degrees
100,000 years
rotation time and speed
1 day, 1000 mph
earth shape created by the forces of gravity causing expansion at the equator
oblate spheroid
study of the shape of the earth
geodisy
tilt of the earth causing seasons
axial tilt, 22-24.5 degrees
amount of time it takes for the axial tilt to change from one extreme to another and back
40,000 years
wobble of the axis of rotation
precession, full one takes 26,000 years
cycles that map out the occurrence of each of earth’s motion cycles to determine when they will coincide potentially causing weather extremes like the ice age
Milankovitch cycles
created by the earth’s rotation and core rich in iron; acts as a shield protecting the earth from the sun’s harmful rays
magnetic field
prior to 1780, school of thought that the earth was formed by a series of infrequent major events such as volcanos and biblical floods
catastrophism
post 1780, school of thought that the earth was shaped by frequent minor events over a long period of time such as rivers, wind, and tectonic shifts
uniformitarianism
location and person who discovered evidence of uniformitarianism with shifts in the rocks, caused the shift from catastrophism to uniformitarianism
Siccar point Scotland, James Hutton, 1780
location and person who recognized large land ripples similar to that of sand likely caused by catastrophic floods leading to the proposal of neo catastrophism
J Harlan Bretz, Channeled Scablands, Washington state, 1920s
modern school of thought that uniformitarianism and catastrophism work in conjunction to shape the earth
neo-catastrophism
law that states the oldest rocks are found on the bottom and the newest on the top
law of superposition
law that states sediments that became rocks were originally laid down horizontally, some remain that way but some shift
law of original horizontality
size order for sections of the geologic time scale
Eon>Era>period>epoch
now the geologic time scale was Originally made
relative age dating based on floral and faunal succession
recent technology allows for this type of dating using radio active elements discovered in 1960’5 by marie curie
absolute age dating
decay of radioactive isotopes over time allows for this method bused on the energy they emit as a parent decays into the daughter
half like decay
Oldest Object we have dating to 4.3 bya found in Jack hills of western australia
Zircon crystal
Earth begins
4.6 bya
2.5 bya divide proterozoic and archeon marked by this event made obvious by the presence of rust in fossilized rocks
great oxidation event
541 mya paleozoic begins with this event marked by the appearance of fossil hard parts
cambrian explosion
mesozoic begins marked by major reptiles
252 mya
66 mya this event marks the end of the mesozoic
KT extinction
KT boundary is rich in this element indicating an asteroid
iridium
Pleistocene begins with continental glaciation starting the quaternary period
2:6 mya
mup of largest known glaciers 18,000 ybp causing a rapid 400 ft rise in sea level upon melting
glacial max
Pleistocene ends win a full meltdown starting the holocene
10,000 ybp
age of rocks on Ship campus
ordovician ,490 myo
number of naturally occuring elements
88
% of the earth’s crust made of the most abundant 8 elements
98.5 %
most abundant 8 elements
oxygen silicon aluminum iron calcium sodium potassium magnesium
Incredibly inert chemical formula that makes up quartz
silica siO2
chemical formula that makes up the earth’s crust
SiAl silica + Al
mafic
Mg+ Fe
makes up oceanic crust
sima silica + ma fic
number of recognized minerals
5,500
naturally occuring inorgan. solids with a definite chemical structure and a unique set of physical properties
Minerals
most obvious and least Reliable physical property
color
physical property refering to now light is reflected, metalic
luster
measured by the mons scale where diamond is a 10 and talc is a 1
hardness
physical property of the color of a Minerals powder
streak
physical property of now light is transmitted through a mineral
Diaphaneity
melting or crystallizing point range
800 - 1200 C
most reliable and least obvious physical property bused on the number of visible geometric planes when a mineral breaks
Cleavage planes
3 cleavage planes
cubic
4 cleavage planes
pyramidal
how a mineral grows
habit
iron ore metalic gray with red streak I plane of cleavage that can’t be seen
hematite
no cleavage, harder than glass
Quartz
4 cleavage planes softer than glass
fluorite
metalic silver with cubic Cleavage and high density
galena
feldspar with strianons and irridesence
plagiocIase
feldspar without strations
potassium
olive green With no Cleavage planes, melts at 1200 c
Olivine
one plane of cleavage sheet like and transparent
muscovite
softer than a fingernail 0 Cleavage planes
Kaolinite
fool’s gold metallic with 0 planes of Cleavage but Cube habit
pyrite
rhombohedralCubik cleavage reacts with HCI
calcite
Cubic Clearage greasy feeling transparent
halite
60-120 cleavage on 2 planes
Hornblende
