Study Guide for Birth of the Earth, Half-life, and Earth History (Excluding 7.1-7.3 Book reading and Powerpoint in class.)

A large cloud of gas and dust.

In the earliest history of the Earth, what was its structure?

Molecular Clouds

What do scientists call clouds of dust and gas?

No, they’re bigger than Earth.

Are they [Molecular clouds] similar to clouds on Earth? Why or why not so?

Gravity

What force in space causes dust and gas to coalesce (contract and solidify)?

Salt

When the scientist does the series of experiments in zero gravity, what was the last material he put in the bag that helped him realize what was happening?

They trade off and they clump up.

What happens to electrons when you have two different materials rubbing together?

4.5 Billion years ago

How long ago did the Earth form?

20 Planets

How many planets were there originally in our solar system?

They collided and combined

What happened to the other 13 planets (since there are only 7 of them left today)?

Deadly particles and solar wind (radiation)

What is so concerning about a giant particle cloud coming from the Sun in the early days of the Earth? (why would it have ended life?)

The Core of the Earth

What feature of the Earth forms the basis for the magnetic field?

Magnetosphere

What do scientists call the magnetic field?

Another Planet

What did early Earth collide with?

It became the moon.

What did the extra material from the collision become?

The tilt on the axis of the Earth.

What about Earth gives us seasons?

Water came from the outer asteroid belt, from comets.

Where did water come from according to the current hypothesis?

It hit into a comet called Temple 1.

What did the Deep Impactor hit?

It confirmed that comets had water.

What did it confirm?

The outer asteroid belt.

Where did the earliest asteroid come from?

Zircon

What mineral was found that also confirmed the presence of water?

Nitrogen, CO₂, and methane.

What 3 gases were present in the atmosphere at this time?

Primitive structures that are living.

What are stromatolites?

Photosynthesis and oxygen.

What metabolic process do they use and what do they produce from that process?

Green

What color were the early oceans?

The stromatolites absorbed most of the oxygen. Then the iron collected in the rocks and oxygen increased.

What happened to all the oxygen at first? (What did that oxygen get tied up into that is still their today?)

Carbon dating or Relative age

Two ways to determine age of fossils?

Relative age

Deals with the placement of a fossil within layers of rocks. When a fossil is found, geologists and paleontologists compare that to fossils found nearby. Older fossils are deeper in the Earth than newer fossils.

Carbon dating (Isotope decay)

Deals with amount of C-14 found in the fossil.

Half-life

How long it takes for 50% of C-14 to decay and turn into boron. (5600 to 5730 years.)

Fossils

Any remains or trace of an ancient organism.

Body Fossils

“The remains of an ancient organism. Examples include shells, bones, teeth, and leaves.”

Trace Fossils

“Evidence of the activity of an ancient organism. Examples include tracks, trails, burrows, tubes, boreholes, and bite marks.”

Fossilization

The process of a once living organism becoming a fossil.

Fossil Fuel

A fuel that was formed from the remains of ancient organisms. Examples include coal, oil, and natural gas.

Preserved remains (Amber), permineralization, molds and casts, replacement, and compression.

5 ways fossils are preserved

Preserved Remains

The rarest form of fossilization is the preservation of original skeletal material and even soft tissue. Ex: Amber

Amber

Fossilized tree sap

Permineralization

A type of fossilization in which minerals are deposited into the pores of the original hard parts of an organism. Most common type of mineralization.

Molds

An impression made in sediments by the hard parts of an organism.In some cases, the original bone or shell dissolves away, leaving behind an empty space in the shape of the shell or bone.

Cast

A structure that forms when sediments fill a mold and harden, forming a replica of the original structure.

Replacement

In some cases, the original shell or bone dissolves away and is replaced by a different mineral. Ex: Dolomite or quartz.

Compression

Some fossils form when their remains are compressed by high pressure. This can leave behind a dark imprint of the fossil. Ex: Leaves and Fern fossils

Index fossils

A fossil that identifies and shows the relative age of the rocks in which it is found. Index fossils come from species that were widespread but existed for a relatively brief period of time. Ex: Ammonites, trilobites, and graptolites.

Microfossils

A fossil that must be studied with the aid of a microscope.

Living Fossils

A modern species or genus that has existed on Earth for millions of years without changing very much. Ex: Lingulata

Marine

Of or belonging to the sea.

Terrestrial

Of or belonging to the land.

Mass extinction

A period of time when an unusually high number of species became extinct.

Absolute Dating

Methods used to determine how long ago something happened.

Extinction

When an organism completely dies out.

Fossils

The remains of past life, such as bones, shells, or other hard parts; may also include evidence of past life such as footprints or leaf impressions.

Geologic Time Scale

A timeline that illustrates Earth’s past.

Relative Dating Methods

Used to determine the order of geologic events in Earth’s history.

Adaptation

A trait that an organism inherits that helps it survive in its natural environment.

Evolution

The change in an organism’s traits over time such that a new species is often the result.

Glaciers

Large sheets of flowing ice.

Paleontologist

A scientist who studies Earth’s past life forms.

Tropical

A climate that is warm and humid.

Variation

Having many differences.