Download Unit 6 Vocabulary Review

N ame
UNIT
6
Period
REVIEW
Date
Unit 6 Concepts and Vocabulary Review
Use this sheet to help you review the vocabulary and key concepts from unit 6.
O bjective G roup 1: Define fossils; list and identify the five types of fossils;
describe how fossils form.
Key Concepts: Some organisms can turn into fossils, there are five types of fossils, and fossils
form in a variety of ways.
Notes: Fossils, Types of Fossils
Activities: What is a fossil activity, What are the 5 types of fossils, What are the types of
fossils analysis, Fossil ID activity
• Fossil – a well-preserved trace or remain of a once living thing
• M old Fossil – an imprint of an organism showing only the outer parts
• Cast fossil – a 3D cast of a fossil made from the mold fossil
• Trace fossil – a fossil that shows evidence of a once-living thing but is not any part
of that organism.
• Carbon film fossil – a fossil that is a thin layer of carbon that can show the soft
parts of an organism (but usually just its body shape)
• Petrified fossil – a 3D fossil that shows the fine details of an organism; made of
minerals
• O riginal rem ains fossil – a fossil of an entire organism preserved in amber, ice, or
tar
• Petrification – a process that forms a fossil by replacing each cell of an organism
with minerals (petrified fossils form this way)
• Prem ineralization – a process that forms a fossil by filling the gaps between the
organism with minerals. After that, the organism decays away.
• Pressure – a process that forms a carbon film fossil by squeezing out the gasses and
liquids of the organism leaving behind a carbon print
• “Entrapment” – a process that forms an original remain fossil by trapping an
organism in amber, ice, or tar
O bjective G roup 2: Use natural evidence to describe the history of an area.
Key Concepts: Evidence of earth’s past is preserved in fossils, tree rings, rock layers, and ice
cores (all known as natural evidence).
Notes: Natural Evidence
Activities: Tree rings activities 1 and 2, Footprints activities 1 and 2
• N atural evidence – any naturally occurring object that gives clues to earth’s past.
This includes tree rings, fossils, ice cores, rock layers, etc.
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O bjective G roup 3: Define relative age; correctly order rock layers
Key Concepts: Layers of sedimentary rock show relative age. The movement of earth’s plate,
igneous rock formation, and faults and unconformities disturb rock layers.
Notes: Relative Age
Activities: Rules of relative age, Relative Age Activity 1, Finding Clues to Rock Layers
• Relative age – the order of an event or object in relation to another event or object.
• Law of superposition – in undisturbed sedimentary rocks layers, the oldest layer is
found on the bottom, and the youngest layer is found on the top.
• Anticline – an upward bend in rock layers (looks like the letter A)
• Syncline – a downward bend in rock (looks like the letter U, it SINKS down)
• Intrusion – an igneous rock formation forming in/through other layers.
• Inclusion – part of another layer found in an intrustion
• Extrustion – an igneous rock formation formed ON TOP of all layers (it reached the
surface of the earth). It is younger than all layers below it. It is older than any layers
that form on top of it.
• Principle of inclusions – inclusions are always older than the rock they are found
in.
• Principle of cross-cutting relationships – anything that cuts through another
layer is younger than what it cut.
• Fault – break or crack in rock layres
• Unconformity – a location where older layers come in contact with much younger
layers (where it shouldn’t)
• Disconformity – an unconformity where erosion/weathering removes layers.
Indicated by wavy lines between layers.
• Angular unconformity – an unconformity where tilter layers meet non-tilted layers.
O bjective G roup 4: Define absolute age, correctly determ ine the absolute age
of rocks.
Key Concepts: Radioactive decay allows scientists to determine the age of rocks by
measuring the remaining parent atoms and counting half-lives.
Notes: Absolute Age
Activities: Decay Rates, Finding Absolute Age
• Absolute age – the approximate age of a rock
• Radioactive decay – the process in which less stable atoms breakdown into more
stable atoms.
• Parent atom – the less stable atom
• Daughter atom – the more stable atom
• Half life – the amount of time it takes half the atoms of a parent element to decay
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