Geologic Time Scale Flashcards
what do you call the remnants of any ancient plant or animal that are preserved in the earth’s rocks.
fossils
this is a record of the life forms and geological events in Earth’s history.
geologic time scale
scientists have divided the _______ years of Earth’s rich history into different spans time to conveniently indicate a major geological or paleontological event.
4.6 billion
this is the method of measuring the absolute age of an event or object
absolute dating
It states that the present is the key to the past, which is based on the principle that natural laws have remained the same throughout time.
uniformitarianism
_______ serve as guide or indicators of
certain geologic periods.
index fossil
based on the principle of _______, it is known that the new layers can be laid down only on top of pre existing older strata, and therefore, older rocks lie below younger ones
superposition
it is the earliest of the geologic ages, which are marked by different layers of sedimentary rock.
Precambrian era
the earliest living organisms were
microscopic bacteria
considered the age of the dinosaurs
jurassic period
enumerate the three eons of the precambrian era
hadean eon
archean eon
proterozoic eon
this is the eon of visible life.
phanerozoic eon
_______ studies the earth
geologists
_______ studies ancient life
paleontologists
enumerate the three eras of the phanerozoic eon
paleozoic era
mesozoic era
cenozoic era
in what epoch is the present time
holocene epoch
this is characterized by Earth’s initial formation-from the accretion of dust and gases and the frequent collisions of larger planetesimals-and by the stabilization of its core and dust and the development of its atmosphere and oceans.
hadean eon
the period when life first formed on
earth.
archean eon
the first oxygen-dependent animals
ediacara fauna
the _______ lasted for 1.9 billion years, almost half the age of earth
proterozoic eon
considered the chaotic eon
hadean eon
the atmosphere began to have oxygen, eukaryotes diversified, multicellular animals appeared, and the continents began to drift away
proterozoic eon
during _______, animals began to breathe air as amphibians came out of the sea
devonian period
what are the periods of the paleozoic era
cambrian ordovician silurian devonian mississippian pennsylvanian permian
the time of ancient life
cambrian period
a rich variety of marine life flourished in the vast seas and the first primitive plants began to appear on land
ordovician period
it is often known as the “Age of Fishes” although significant events also happened in the evolution of plants, the first insects and other animals.
devonian period
this period is characterized by shallow-water limestone deposits occupying the interiors of continents especially in the Northern Hemisphere.
mississippian period
this is recognized as a time significant advance and retreat by shallows seas. Many nonmarine areas the equator became coal swamps during this period
pennsylvanian period
at the end of this period was the largest mass extinction in history. what period is this and what was the extinction called
permian period , permian extinction
enumerate mesozoic era’s periods
triasssic period
jurassic period
cretaceous period
mesozoic era is derived from the Greek term
for ______
“middle life”
during this era the continents began to move into their present-day configurations.
mesozoic era
during this period, oceans formed as land shifted and broke out of one big supercontinent into smaller ones.
cretaceous period
This period is the longest period of the phanerozoic.
cretaceous period
It was the interval of time during which the continents assumed their modern configuration and geographic positions and during which earth’s flora and fauna evolved toward those of the present.
cenozoic era
cenozoic era is divided into two periods. what are these two
tertiary period
quaternary period
first major worldwide division of rocks and time of the Paleogene Period. The most complete picture of this epoch is the terrestrial life and environments.
paleocene epoch
it is derived from the Greek eon, for “dawn” referring to the appearance and diversification of many modern groups of organisms, especially mammals and mollusks.
eocene epoch
it is derived from Greek and means the “epoch of few recent forms”, referring to the sparseness of the number of modern animals that originated during that time.
oligocene epoch
earliest major worldwide division of the Neogene Period
miocene epoch
second of two worldwide divisions of the Neogene Period
pliocene epoch
this period has been characterized by several periods of glaciation
quaternary period
it is one of the best studied parts of the geologic record.
quaternary period
it is best known as a time during which extensive ice sheets and other glaciers formed repeatedly on the landmasses and has been informally referred to as “Great Ice Age”.
pleistocene epoch
enumerate the major methods of relative dating
Radiometric dating
Amino acid dating
Dendrochronology
Thermoluminescence
This technique solely depends on the traces of radioactive isotopes found in fossils. The rate of decay of these elements helps determine their age, and in turn the age of the rocks.
Radiometric dating
Each tree has growth rings in its trunk. This technique dates the time period during which these rings were formed.
Dendrochronology
Physical structure of living beings depends on the protein content in their bodies. The changes in this content help determine the relative age of these fossils.
Amino acid dating
It determines the period during which certain object was last subjected to heat. It is based on the concept that heated objects absorb light, and emit electrons. The emissions are measured to compute the age.
Thermoluminescence
________ estimate whether an object is younger or older than other things found at the site. this does not offer specific dates, it simply allows to determine if one artifact, fossil, or stratigraphic layer is older than another.
relative dating methods
________ provide 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 dating methods
_______ are atoms of the same element that have similar number of protons but different numbers of neutrons
isotopes
other isotopes are unstable, in that they break down into stable isotopes or other elements. what are they called?
radioactive
the unstable radioactive isotope is called the _______
parent isotope
the stable isotope produced by the radioactive decay is called the _______
daughter isotope
During this time continental landmasses were low and sea levels were rising. This meant rich shallow sea ecosystems with new ecological niches.
silurian period
time when life outside of the oceans began diversify.
triassic period
The term Cenozoic originally spelled _________
cainozoic
