Earth Past
False
Earth's climate has stayed the same throughout the past
cast
a fossil copy of an organism made when a mold of the organism is filled with sediment or mineral deposits
correlate
a geologist who needed to _______ two rock formations in different areas could match exposed rock layers
radioactive decay
a process that uses the properties of atoms in rocks and other objects to find their ages
absolute dating, relative dating
a rock's exact age can be determined whereas with ____________, a rock's age is compared to the ages of other rocks
half life
amount of time it takes for one half of the original amount of an isotope to decay
disconformity
an unconformity between two sedimentary layers is classified as a -
missing layer
an unconformity is a __________ of rock
carbon film
are formed when a thin film of carbon is left forming an outline of the original organism
fossil
carbon-14
constant rate
characteristic of radioactive decay makes it useful for determining the absolute age of samples
absolute
dating uses the properties of atoms in rocks and other objects to find their ages
relative dating
determining the order of events and the relative age of rocks by examing the position of rocks in a sequence is called _________
trace fossils
dinosaur footprints are -
petrified wood
example of a fossil with altered hard parts includes ___________
insect in amber
example of a fossil with original preservation includes an ______________
nests
example of a trace fossil includes __________
remove liquids
fish _________ carbon film
carbon film
fossil formed when an outline of the original organism is formed from left-over carbon
remains
fossils are the ___________, imprints, or traces of once-living organisms preserved in rock
index fossils
fossils of species that lived on earth for short periods of time and were abundant and wide spread geographically
C-14
fossils up to 50,000 years old can be dated with _______
unconformities
gaps in rock layers
5,730 years
half life for C-14
quick burial
helps preserve organisms as fossils
lived over short period of time
index fossils are useful to geologist if the fossils
amber
is the hardened tree sap that fossil insects are preserved in
radioactive decay
measured in half lives
remains
missing layer
fossils
molds, casts, tace, and petrified wood are all examples of _________
fossil
most often form when a dead organism is buried in sediments
nonconformities
occur when sedimentary rocks are deposited on top of uplifted and eroded metamorphic or igneous rocks
nonconformity
occurs when sedimentary rock overlies igneous rock
bottom
oldest rock layer in undisturbed rock sequence
trace
preserved animal tracks are called _________
relative age
principle of superposition can be used to determine _____________
index fossil
radio carbon dating is useful for finding -
hard
radioactive decay
uniformities
remains of species that existed on earth for relatively a short period of time
fossils
rock layers are correlated if they both contain the same _________
law that oldest layer is on bottom
states that for undisturbed rocks -
hard
the ______ parts of organisms are most likely to become fossils
mold
the cavity left behind in the rock after an organism's hard part has decayed
radiometric dating
the process of calculating the absolute age of a rock by measuring the amounts of parent and daughter materials in a rock and by knowing the half life of the parent
half life
the time is takes for half of the atoms in an isotope to decay
existed
to be a useful index fossil, a species must have
mold
trace
radiometric dating
used to determine absolute age of rock
fossil
way to tell a palenontologist when, where and how an organism lived
unconformity
when part of the rock record is destroyed the erosional gap that forms is an _________
