Chapter 6: A Trip Through Geologic Time

When did the oceans and atmosphere form?

Which rock layer is oldest?

An igneous intrusion is ________________ than the rock it cuts through.

Which period do we currently live in?

Fossils of widely distributed organisms that lived during a geologically short period.

Which type of fossil is the?

Which rock layer is youngest?

Term used to refer to a group of related organisms that has died out and has no living members.

The age of a rock given as the number of years since the rock formed.

How old is a rock that contains 12.5% of its original Potassium-40?  half-life 1.3 by

A fossil that is a solid copy of an organism's shape, formed when minerals seep into a mold.

Radioactive dating works best for which type of rock?

Which type of fossil is the?

A type of fossil that provides evidence of the activities of ancient organisms.

A loose collection of ice and dust that orbits the sun, typically in a long narrow orbit.

Process in which the nuclei of radioactive elements break down, releasing energy and particles.

The age of a rock compared to the ages of other rocks.

Which era do we currently live in?

Originally, the geologic time scale placed Earth’s rocks in order by

Which two gases made up Earth's first atmosphere?

The Earth's earliest atmosphere lacked which gas to support life as we know it?

The radioactive element used to determine the age of more recent remains of organisms

A sample has 12.5% of its original radioactive material, how many half lives have passed?

How old is a rock that contains 50% of its original Potassium-40?  half-life 1.3 billion years

A break in Earth's crust along which rocks move.

What had to happen to the Earth for liquid water to form?

Change over time; the process by which modern organisms have descended from ancient organisms.

A scientist who studies fossils to learn about organisms that lived long ago.

An igneous rock layer formed when lava flows onto Earth's surface and hardens.

A record of the geologic events and life forms in Earth's history.

An igneous rock layer formed when magma hardens beneath Earth's surface.

A type of fossil consisting of extremely thin coating of carbon on rock.

One of the units of geologic time into which geologists divide eras.

Between which rock layers is there an unconformity?

A gap in the geologic record that shows where rock layers have been lost due to erosion.

A type of fossil that is a hollow area in sediment in the shape of an organism or part.

The preserved remains or traces of an organism that lived in the past.

The law that says that the older layers or rock are below the younger layers.

One of the three long units of geologic time between the Precambrian and the present.

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

The time it takes for half of the atoms of a radioactive element to decay.