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rock and fossil record
Vocabulary
30
Science
7th Grade
01/09/2007

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Term
uniformitarianism
Definition
a principle that states that geologic processes that occurred in the past can be explained by current geologic processes
Term
catastrophism
Definition
a principle that states that geologic change occurs suddenly
Term
paleontology
Definition
the scientific study of fossils
Term
give one example of catastrophic global change
Definition
a global climate change caused by an asteroid striking Earth
Term
describe the work of 3 types of paleontologists
Definition
vertibrate paleontologists-study fossils of animals that have backbones
invertibrate paleontologists-study fossils of animals that do not have backbones
paleobotanists study plant fossils
Term
which came first---uniformitarianism or catastrophism
Definition
catastrophism came first
Term
relative dating
Definition
any method of determining whether an event or object is older or younger than other events or objects
Term
superposition
Definition
a principle that states that younger rocks lie above older rocks if the layers have not been disturbed
Term
geologic column
Definition
an arrangement of rock layers in which the oldest rocks are at the bottom
Term
unconformity
Definition
a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time
Term
disconformity
Definition
exists where part of a sequence of parallel rock layers is missing
Term
nonconformity
Definition
exists where sedimentary rock layers lie on top of an eroded surface of nonlayered igneous or metamorphic rock
Term
angular conformity
Definition
exists between horizontal rock layers and rock layers that are tilted or folded
Term
list 2 events and 2 features that can disturb rock-layer sequences
Definition
events-folding and tilting

features-faults and intrusions
Term
how are physical features used to determine relative ages
Definition
the way physical features form determines the order in which events occurred thereby determining relative ages
Term
absolute dating
Definition
any method of measuring the age of an event or object in years
Term
isotope
Definition
an atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons
Term
radioactive decay
Definition
the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element
Term
radioactive dating
Definition
a method of determining the age of an object by estimating the relative percentages of a radioactive (parent) isotope and a stable (daughter) isotope
Term
half-life
Definition
the time needed for half of a sample of a radioactive substance to undergo radioactive decay
Term
list four types of radiometric dating
Definition
potassium-argon
uranium-lead
strontium-rubidium
carbon-14
Term
Rubidium-87 has a half-life of?
Definition
49 billion years
Term
fossil
Definition
the trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock
Term
trace fossil
Definition
a fossilized mark that is formed in soft sediment by the movement of an animal
Term
mold
Definition
a mark or cavity made in a sedimentary surface by a shell or other body
Term
cast
Definition
a type of fossil that forms when sediments fill in the cavity left by a decomposed organism
Term
index fossil
Definition
a fossil that is found in the rock layers of only one geologic age and that is used to establish the age of the rock layers
Term
fossils are most often preserved in?
Definition
rock
Term
describe 3 types of trace fossils
Definition
tracks
burrows
coprolites
Term
why is the fossil record an incomplete record of the history of life on Earth?
Definition
because most organisms, such as organisms that have soft body parts, did not become fossils, and many fossils have yet to be discovered
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