WEEK 7 DATING & TIME SCALE Flashcards
Determine a calendar of sequences of events in history of earth
Dating
examples of relative dating (3)
stratigraphy, seriation, fluorine
Estimate whether an object is younger or older than other things found at the site.
relative dating
helps archaeologists create a relative timeline, with older layers at the bottom and younger layers at the top.
stratigraphy
laws of stratigraphy (4)
law of superposition, cross-cutting, initial horizontality, strata continuity
Stratigraphy was proposed by?
Nicolas Steno
This law states that Strata continues until it reaches other solid bodies–usually large bodies of water.
strata continuity
This law states that newer rocks sits on top of Older rocks within rock layers.
Superposition
Artifacts found in these layers are at least as old as the layer they are discovered in.
stratigraphy
It can be deduced through this law that Strata across river valleys and canyons used to be connected until it got eroded away.
Strata continuity
Things that Cross-Cut layers likely postdate them.
cross cutting
This law states that the Strata–layers of rock sediments that are faced perpendicular or inclined to the horizon was at one time parellel to said horizon.
initial horizontality
This law is used to study the sequence of events of the creation of certain types of rocks.
cross-cutting
A technique that analyzes how much of the chemical ________ has been absorbed by bones from the surrounding soils to determine how long the specimen has been underground.
fluorine dating
A technique that was common in the mid 20th century, looks at changes in certain styles of artifacts present at a site.
seriation
Provides more specific origin dates and time ranges, such as an age range in years. How specific these dates can be will depend on what method is used.
absolute
examples of absolute dating (6)
archaeomagnetic dating, k-ar ar-ar, fission track, thermoluminescence, radiocarbon, dendrochronology
One of the most widely known radiometric dating techniques
radiocarbon dating
Useful for determining the age of pottery or ceramics
thermoluminescence
it can be used to date materials containing crystalline minerals to a specific heating event in the past
thermoluminescence
A technique that determines the age of various minerals and glasses based on the trails of damage done by the spontaneous fission of uranium-238, the most abundant isotope of uranium.
fission-track
Measure the ratio of argon gas in igneous volcanic rock to estimate how much time has elapsed since the rock cooled and solidified.
k-ar ar-ar
Magnetic particles in most materials of geological origin, such as rocks and clay, are analyzed to track shifts in the earth’s magnetic fields over time.
archaeomagnetic
It divides up the history of the earth based on life-forms that have existed during specific times since the creation of the planet.
geologic time scale
measures the decay of the radioactive isotope Carbon-14 (C-14) in any organic material found in archaeological deposits, such as wood, plants, textiles, and human or animal remains to determine its age.
radiocarbon decay
Since most trees produce a ring of new wood annually, archaeologists use the variations in cross-sections of wood to produce timelines.
dendrochronology
the largest units of geologic time, spanning hundreds of millions to billions of years and each represents a significant phase in Earth’s history.
eons
Time of prokaryotes & earliest period
Precambrian
Precambrian time (4)
Phanerozoic, proterozoic, hadean, archean
earliest eon in earth’s history
hadean
saw the development of the first multicellular organisms, as well as the first complex ecosystems.
proterozoic
was a time of great diversification of life, with the first animals appearing during this time.
proterozoic
The first single-celled organisms appeared during this eon, as well as the first cyanobacteria, which began to produce oxygen.
archean
It was a time of intense volcanic activity and bombardment by asteroids and comets.
hadean
It was a time of great change on Earth, as the planet cooled and life began to emerge.
archean
This is the eon of visible life, and is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic.
phanerozoic
It is the eon in which we live, and is characterized by the emergence of all major groups of plants and animals.
phanerozoic
first cyanobacteria & began to produce oxygen
archean
Phanerozoic eon is divided into three eras:
paleozoic, mesozoic, cenozoic
subdivisions of eons, span tens to hundreds millions of years
eras
Earth’s continents were combined into a single supercontinent called Pangaea.
periods of paleozoic (6)
carboniferous, permian, devonian, silurian, ordovician, cabrian
is known for the rise of invertebrates, fish, amphibians, reptiles, and the first land plants.
paleozoic
age of invertebrates, trilobites
cambrian
non vascular plants
ordovician
age of fishes
devonian
age of amphibians
carboniferous
age of reptiles
permian
also known as age of dinosaurs
mesozoic era
age of vesicular plants
silurian
diversity in reptiles, ended in mass extinction
triassic
the dinosaurs were the dominant land animals on Earth.
mesozoic era
periods of mesozoic era (3)
triassic, jurassic, cretaceous
age of dinosaurs
jurassic
end of the age of dinosaurs
cretaceous
a time of great diversity among mammals, and is also marked by the rise of human civilization.
cenozoic
the continents have drifted to their present positions, and the mammals have diversified to fill many different niches on Earth.
cenozoic
It is also known as the “age of mammals.”
cenozoic
early humans
neogene
age of mammals
paleogene
evolutions and dispersion of humans
quaternary
