Science/Wasson/ Plate tectonics. Fossils part 1.

What is a fossil?

• any dead organism

• a perfect copy of a rock

• the preserved remains or traces of an organism

• an unusual type of rock

How do most fossils form?

• The hard parts of an organism dry out in the air.

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

• The soft parts of an organism change to stone

• Freezing preserves the remains of an organism.

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

• organisms that are more complex than those alive today.

• both simple and complex organisms

• only organisms that are alive today

• organisms that are simpler than those alive today

The process by which all the different kinds of living things have changed over long periods of time is called

• sedimentation

• replacement.

• deposition

• evolution

A fossil formed when minerals replace all or part of an organism is called a

• mold

• petrified fossil

• cast

• trace fossil

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

• trace fossils

• remains preserved in amber

• carbon films

• molds and casts

The relative age of a rock is

• its age compared to the ages of other rocks

• less than the age of the fossils the rock contains

• the number of years since the rock formed.

• its age based on how much carbon-14 the rock contains

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

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

  it.

• neither older nor younger than the other layers.

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

• always older than any vertical layers

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

• trace fossils

• petrified fossils

• index fossils

• carbon film fossils

Radioactive dating enables geologists to determine

• the age of the atoms in a rock

• the half-life of a fossil organism.

• the relative ages of rocks

• the absolute ages of rocks.