unit 2 1-63 test 64-68 weekly quiz 3 69-73 weekly quiz 4 Flashcards
what is the concept of deep time
the concept is that earth has had a multi-billion year history
what sets the study of geology apart from all other sciences except astronomy?
applying vast amounts of time (billions of years) to scientific principles set geology apart from all other sciences except astronomy.
compare absolute age dating to relative age dating.
absolute age dating specific dates or specific units of time.
relative age dating placing events in sequential order (which came first, second, ect.)
what type of time indicator are fossils - relative time or absolute time?
fossils are relative time indicators
what are the three characteristics of a guide fossil?
easy to identify, were geographically widespread but existed only for a relatively short time period (quick appearance and quick extinction).
which two geologic principles were used to create the first maps of the earths history?
the principle of superposition and the principle of fossil succession and logic
what is the main difference between time units and time stratigraphic units
time unit is an interval of relative time based on specific fossil assemblages.
time stratigraphic units is units of rocks (layers of rocks) that were deposited during specific relative time intervals (according to the fossil record)
place the following in order from the longest to shortest time intervals: eons, eras, periods, epochs, and ages.
eon, era, period, epoch, and age.
sort the names in correct order, from oldest to youngest, for the four eons
hadean eon (4.56-4.0 billion years), archean eon (4.0-2.5 billion years), proterozoic eon (2.5-0.542 billion years), and phanerozoic eon (542 million years to today)
how are the eras generally separated or classified?
generally separated by catastrophic life extinctions boundaries
list the names in correct order, from oldest to youngest, the three eras of the phanerozoic eon.
paleozoic era (paleo=older)(542-251 million years) mesozoic era (meso=middle)(251-65 million years) cenozoic era (ceno=younger)(65 million years to today)
eras are subdivided into multiple time units called __?
periods
what are the three modifiers used to divide a time unit?
late(last), middle, early(first)
what defines a time stratigraphic unit?
units of rocks (layers of rocks) that were deposited during a specific time interval (jurassic, etc.)
which of the following pairs are equivalent to one another; period, epoch, system, series?
epoch and period are time units based on life and age
series and system are time stratigraphic units based on life and rocks stage - ignore.
compare the informal modifiers of time units with modifiers of time stratigraphic units.
informal time modifiers late (last), middle, early(first) are based on life and extinctions.
time stratigraphic units upper, middle, and lower are based on units of rocks (layers of rocks) that were deposited during a specific time interval.
define a rock stratigraphic unit.
rocks defined by the physical attributes and characteristics of the described rocks (time is ignored)
give a simple definition for a geologic formation?
a mappable rock unit with distinctive upper and lower boundaries
in general, how are formations named?
formations have a two-part name
first part= geographic location (type section locality)
second part= rock type of the formation
what is a stratigraphic unit?
any sequence of rock units found in a given region.
what is a type section?
a rock unit (stratigraphic section) at a location that is most representative for comparison purposes
about what year did bishop james ussher assign to the earths creation?
6,000 years ago on october 26, 4004 bc
what was the heat source that buffon and kevin missed while they were trying to calculate earths age
the radioactive decay that is heating the earth
what fact did joly not take into account while trying to calculate earths age using salinity?
the huge deposits of salt from evaporated seawater; these deposits occur throughout geologic time. ocean salts other than NaCl give a totally different time.
what is dendrochronology?
tree ring dating
how far in time is dendrochronology useful?
can extend time back to 12,000 years
what are varves?
thin layers of sediments that are added during the various seasons.
what rock type was used in counting the evaporate lake varves of west texas for age dating?
permian-aged casteel gypsum formation
what is the ice coring program in greenland and antarctica can possibly explain about the earth?
reenland can stretch back 250,000 years and antarctca backto 740,000 years.
trpped gases can give us a record of pas greenhouse gases on earth.
scientific study of ice cores can reveal ancient climates going back 250,000 years.