untitled

Geologic Time Scale

Mr. Reece

Speight Middle School

8th Grade Science

Geologic Time Scale

• A record of the major events and diversity of life forms in Earth's history

• Began when Earth was formed and goes on until the present day

• Eons ----> Eras ----> Periods

Multiple Choice

Paleozoic, Mesozoic & Cenozoic are all ________.

• Epochs

• Eras

• Periods

• Eons

Time Scale Events

• At the end of each era, a mass extinction occurred

• Although there were other extinctions going on during each period of geologic time

Multiple Choice

Describe how geologists separate time periods.

• By special events that have happened in that period.

• By looking at the Relative Time of a Fossil

• By counting the years a fossil has been preserved

• By the animals in the time period.

The Fossil Record

• Using the fossil record, paleontologists have created an idea of the different types of common organisms in each geologic period

• Ex: Mammals appear in Mesozoic era ---> Cenozoic era

Precambrian Era

• Earth's first era of time

• Began 4.6 mya: Creation of Earth

• Began with simple life forms such as bacteria and simple algae

• A rise of simple organisms such as jellyfish and sea worms by the end of the era

• Few fossils from era

Era Major Events

• 1. Formation of Sun & light

• 2. Creation of the Earth

• 3. Creation of atmosphere through volcano out-gassing

• 4. Creation of oceans

• 5. Creation of life

Multiple Choice

How old do Paleontologists believe the Earth is?

• 2021 years old

• 4.6 million years old

• 4.6 billion years old

• 3.6 billion years old

Paleozoic Era

• Began with the early invertebrates (trilobites and brachiopods) --> early vertebrate fish --> arachnids and insects ---> first amphibians --> reptiles became dominant near end

• Early land plants included simple mosses, ferns, and then cone-bearing plants

• By the end of the era, seed plants were common

Era Mass Extinction

• The mass extinction that ended the era caused most marine invertebrates as well as amphibians to disappear

Mesozoic Era

• Reptiles were the dominant animals of this era, including dinosaurs

• Small mammals and birds appeared

• Toward the end of the era, flowering plants appeared and the kinds of mammals increased

Era Mass Extinction

• The mass extinction that ended the era caused the dinosaurs to become extinct

Open Ended

What animal group dominated the Mesozoic era?

Cenozoic Era

• New mammals appeared while others became extinct

• The diversity of life forms increased

• Flowering plants became most common

• Humans are also part of the most recent period of this era

Open Ended

What animal group has dominated the Cenozoic era?

Multiple Choice

Name the 4 time frames in order from oldest to youngest.

• Precambrian Time, Paleozoic Era, Mesozoic Era, Cenozoic Era

• Mesozoic Era, Precambrian time, Cenozoic Era, Paleozoic Era

• Paleozoic Era, Mesozoic Era, Precambrian Time, Cenozoic

Multiple Choice

The time span that lasted the longest was the...

• Precambrian

• Mesozoic

• Paleozoic

• Cenozoic

Open Ended

What era are we living in now?

Multiple Choice

Fossils are ______ remains of ancient organisms.

• preserved

• old

Multiple Choice

Catastrophism is the idea that quick,_____ events change the Earth.

• ocean

• violent

Multiple Choice

Examples of a trace fossil are tracks, nests, and __________.

• footprint

• mold

Multiple Choice

Uniformitarianism is the principle that states geological events ( earthquakes,volcanoes ) have occurred in the ____ and will occur in the present and future.

• past

• core

Multiple Choice

In a rock layer, the oldest rocks are at the ____________.

• bottom

• top

Multiple Choice

A fault in a rock layer is younger than the layers it ______ through.

• sets

• cuts.

Multiple Choice

Index fossils are found in _______ layers.

• rock

• soil

Multiple Choice

Index fossils help identify the ________ of rock layers.

• age

• match

Multiple Choice

Geologists study the relative _____ of rock layers.

• look

• age

Multiple Choice

These fossils are found in rock layers and identify the relative age of the layer.

• Index

• Preserved

Multiple Choice

Preserved remains of plants and animals from the remote past are called?

• Sedimentary rocks

• Radioactive dating

• Decayed organisms

• Fossils

Multiple Choice

The Law of Superposition states

• Younger rocks layers are on top of older rock layers

• Fossils are found in sedimentary rocks

• Older rock layers are on top of younger rock layers

• Absolute age dating

Multiple Choice

Use relative age dating to put the rock layers in correct order from oldest to youngest.

• B, D, A, E, C

• C, E, D, A, B

• A, C, E, D, B

• C, E, D, B, A

Multiple Choice

Which is the youngest rock layer?

• Siltstone

• Conglomerate

• Mudstone

• Limestone

Multiple Choice

Which of the fossils is the oldest?

• Dinosaur

• Bird

• Shell

• Ammonite

Multiple Choice

Which period are we currently in?

• Quaternary
• Holocene
• Jurassic
• Tertiary

Multiple Choice

Approximately how old is the Earth?

• 250 million years

• 4 billion years

• 1.5 billion years

• 4.6 billion years

Multiple Choice

The state of no longer existing

• Sedimentary layers

• Fossils

• Diversity

• Extinction

Multiple Choice

An animal has sharp, pointy teeth, what can we infer about this animal?

• The animal lived in the water

• The animal lived near the beach.

• The animal is a carnivore.

• The animal only ate plants.

Multiple Choice

If a scientist found a fish fossil in the desert, what can they infer?

• An animal ate the fish.

• The water covered the area long ago.

• Today's fish looks the same

• The fish is endangered.

Multiple Choice

What are the oldest fossils and why?

• B, C- because they are closest to the top

• A, B- because they are closest to the bottom

• They are all the same age- because they are all found on layer 2

• A, B- because they are found closest to the top

Multiple Choice

_______________ is the long span of time that begins geologic time.

• Precambrian Time
• Cenozoic Time

Multiple Choice

With ________ dating, a rock’s exact age can be determined, whereas with ________ dating, a rock’s age is compared to the ages of other rocks.

• absolute, relative

• relative, absolute

• true, absolute

• relative, approximate

Multiple Choice

Which of the following is least likely to become fossilized?

• bones

• teeth

• skin

• shells

Multiple Choice

What do earthquakes tell scientists about the history of the planet?

• Earth’s climate is constantly changing.

• The continents of Earth are continually moving.

• Dinosaurs became extinct about 65 million years ago.

• The oceans are much deeper today than millions years ago.

Multiple Choice

The diagram shows layers of sedimentary rock. Assuming that this rock formation is undisturbed, What is the relative age of layer C?

• It is the youngest rock layer.

• It is the oldest rock layer.

• It is older than B and younger than D.

• It is younger than B and older than D.

Multiple Choice

How do scientist know when a mass extinction took place?

• They find more fossils of plants.

• They find fossils of animals that died suddenly.

• They find a sudden disappearance of many fossil species.

• They find evidence of changes in Earth’s atmosphere.