History of Life on Earth Geological Time Scale and Fossils

It distinguishes Earth's

history based on life-forms that existed at certain

times since the planet's formation.

Geologic time scale

Without these, geologists might not have

established that the world has a past that

predates humanity.

Fossils

Fill in the Blank: The concept of a Geologic Time Scale is

that a "_____" is a basic unit of

geological time during which a specific

kind of rock system is produced.

Period

Fill in the Blank: When "periods" are compacted together

according to their characteristics, this

geologic division will comprise the so-

called "_____"

Era

Some "periods" have their own

subdivision; what are these geologic subdivisions

are called?

Epoch

When "eras" are grouped together, this

will create the longest geologic

subdivision, these are called?

Eon

Which of the following are one of the four major Eras of the GTS?

Precambrian Era

Which of the following are one of the four major Eras of the GTS?

Mesozoic Era

Which of the following are one of the four major Eras of the GTS?

Paleozoic Era

Which of the following are one of the four major Eras of the GTS?

Cenozoic Era

Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian are all periods under which era?

Paleozoic era

Triassic, Jurassic, and Cretaceous are all periods under which era?

Mesozoic era

Tertiary and Quaternary are all periods under which era?

Cenozoic era

When did the Cambrian explosion occur?

About 545 million years ago

Which of the following best describes the Cambrian explosion?

Sudden increase in diversity of life forms

Most major animal groups

appeared during this time.

The Cambrian Explosion

How long did the formation of complex, multicellular organisms appear?

Took place over 5–10 million years

This marked the beginning

of complex animal life

The Cambrian Explosion

Set the foundation for

modern ecosystems and explains rapid

diversification seen in

the fossil record.

The Cambrian Explosion

Preserved remains or traces of ancient organisms usually found in sedimentary rocks.

Fossils

These provide evidence of

past life and environments.

Fossils

Molds, casts, petrified fossils, original remains, carbon film, and trace are all types of?

Fossils

Impression made in a substrate.

Molds

Negative image of an organism.

Molds

Formed when a mold is filled

with minerals

Casts

Examples can be; shells

bones and teeth.

Casts

Shell impressions are examples of?

Molds

Organic material converted into stone

Petrified

Petrified trees, Coal balls (fossilized plant tissues) are all exampls of which type of fossil?

Petrified

Entire organism preserved.

Can be frozen, trapped in tar,

dried, or encased in amber

Original Remains

Woolly mammoth

Insects in amber (Baltic Sea

region) are all examples of?

Original Remains

Thin carbon layer left in

sedimentary rock

Carbon Film

Leaf impressions is an example of?

Carbon Film

Records activities or behaviors

of organisms

Trace Fossils

Trackways

Burrows and nests

Coprolites (fossilized dung)

are all examples of?

Trace Fossils

What way of fossilization is when an organism trapped in amber or hardened plant sap, Little to no change in original material.

Unaltered preservation-

What way of fossilization is when Organic material is

replaced by minerals. Common in bones and wood.

Permineralization / Petrification

What way of fossilization is when the original hard parts are dissolved and replaced with minerals like calcite or silica.

Replacement

What way of fossilization is when other elements

removed, Only carbon remains.

Carbonization / Coalification

What way of fossilization is when minerals rearrange into more stable forms, small crystals turn into larger crystals.

Recrystallization

What way of fossilization is when molds and casts form

after organism is dissolved.

Authigenic preservation (Molds and casts)

Why Do We Date Fossils?

To determine their age

Why Do We

Date Fossils?

To place them in the

Geological Time Scale

Why Do We

Date Fossils?

To understand

relationships between

fossils

Based on rock layers

Does not give exact age

Compares fossils as older or younger. Identify which of the two ways of ddating fossils is this.

Relative Dating

Determines actual age of fossils.

Uses radioactive isotopes. Identify which of the two ways of ddating fossils is this.

Absolute Dating

Sedimentary layers are deposited in a specific time- youngest rocks on top, oldest rocks at the bottom. State which of the following law of how relative age is determined it this.

Law of superposition

Deposition of rocks happen horizontally- tilting, folding or breaking happened recently. State which of the following law of how relative age is determined it this.

Law of original horizontality

State which law is this: If an

igneous intrusion or a fault cuts through existing rocks,

the intrusion/fault is YOUNGER than the rock it cuts

through.

Law of cross-cutting

(guide fossils/ indicator fossils/ zone

fossils): fossils from short-lived organisms that lived in

many places; used to define and identify geologic periods.

Index Fossils