FOSSILS

UNIT ONE

WARM-UP #1

•How do most fossils form?

ANSWER

•Living things die and their remains are covered by sediments.

WARM-UP #2

•A fossil formed when minerals replace all or part of an organism is called____________.

ANSWER

•Petrified fossil

WARM-UP #3

•Which type of fossil can provide clues about the activities of ancient organisms?

ANSWER

•Trace fossil

VOCABUALRY

•Fossil•Mold & cast•Petrified

VOCABULARY

• Fossil• A trace of an ancient organism that has been preserved in rock• Mold & cast• A fossil formed when an organism buried in sediment dissolves, leaving a hollow area

VOCABULARY

•Petrified•A fossil in which minerals replace all or part of an organism

WARM-UP #4

• The fossil record shows that life on Earth has changed over time. For example, paleontologists have found that older rocks contain fossils of

ANSWER

•organisms that are simpler than those alive today.

WARM-UP #5

•The relative age of a rock is

ANSWER

•its age compared to the ages of other rocks.

WARM-UP #6

•The law of superposition states that, in horizontal layers of sedimentary rock, each layer is

ANSWER

•older than the layer above it and younger than the layer below it.

VOCABUALRY

•Carbon film•Trace•Paleontologist

VOCABUALRY

• Carbon film• A type of fossil consisting of

an extremely thin coating of carbon on rock

• Trace• A type of fossil that provides

evidence 0f the activities of the ancient organism

VOCABUALRY

•Paleontologist•A scientist that studies fossils to learn about organisms that lived a long time ago

WARM-UP #7

•What is the age of an intrusion of igneous rock in relation to the sedimentary rock layers through which it passes?

ANSWER

•always younger

WARM-UP #8

•The fossils of organisms that were widely distributed but only lived during a short period of time are called

ANSWER

•index fossils.

WARM-UP #9

•Why are index fossils useful to geologists?

ANSWER

•They tell the relative age of the rock in which they occur.

VOCABUALRY

•Relative age•Absolute age•Law of superposition

VOCABUALRY

• Relative age• The age of a rock compared to the ages of rock layers• Absolute age• The age of a rock given as the number of years since the rock formed

VOCABULARY

• Law of superposition• The geologic principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it

WARM-UP #10

•The earliest life forms were

ANSWER

•single-celled organisms.

WARM-UP #11

•What is a fossil?

ANSWER

•the preserved remains or traces of an organism

WARM-UP #12

• In which type of fossil might you find the remains of an insect preserved with little or no change?

ANSWER

•fossil in amber

VOCABUALRY

•unconformity•Index fossil

VOCABUALRY

• Unconformity• A place where old, eroded rock surface is in contact with a newer rock layer• Index fossil• Fossils distributed organisms that lived during only one short period

WARM-UP #13

• A type of organism that no longer exists on Earth is said to be __________.

ANSWER

•extinct.

WARM-UP #14

•Fossils usually occur in _____________________ rock.

ANSWER

•sedimentary

WARM-UP #15

•Generally, only the ________ parts of organisms become fossils.

ANSWER

•hard

VOCABUALRY

•Hydrocarbon•Petroleum

VOCABUALRY

• Hydrocarbon• An energy-rich chemical compound that contains carbon and hydrogen atoms• petroleum• Liquid fossil fuel; oil

WARM-UP #16

•Footprints and trails are examples of__________________.

ANSWER

•Trace fossils

WARM-UP #17

•The law of superposition helps geologists determine the________________ age of a rock layer.

ANSWER

•relative

WARM-UP #18

•Rock layers are always _______________ than the faults that cut across them.

ANSWER

•older

VOCABUALRY