geologic time scale - SharpSchooltmspcs.sharpschool.com/.../Crate/geologic_time_scale.pdfGeologic...
Transcript of geologic time scale - SharpSchooltmspcs.sharpschool.com/.../Crate/geologic_time_scale.pdfGeologic...
Geologic Time Scale and Change Over Time
Module 1.4
Geologic Time Scale
Geologic time—Earth’s history is divided into time units that make up a geologic time scale.
● Time units on the scale are based on the appearance or disappearance of types of organisms (such as trilobites) using index fossils that lived during specific periods of time.
Geologic Time Scale
Major Time Divisions
a. Eons—longest subdivision; based on abundance of fossilsb. Eras—marked by significant worldwide changes in the types of fossils present in rockc. Periods—based on types of life existing worldwide at a particular timed. Epochs—characterized by differences in life-forms, but differences can be regionalrather than global
Fossils
Geologic time can be subdivided only if fossils are present in rock records.*This means that more recent time periods have more division than time periods from longer ago*Why do you think this is?
Color Coding the Time Scale1. Using pg 103 of the text book, color code
your copy of the Geologic Time Scale the same way (lightly color)
2. Draw red lines along the 2 mass extinctions
3. Label the first appearrences of life, trilobites, fish, plants, amphibians, reptiles, birds, flowering plants, mammals, and humans
4. Then draw an arrow along the side showing the oldest time period until today
5. Copy and answer the following on the back:
1. What Era do we live in?
2. When did the dinosaurs become extinct?
3. When did life first appear?
Exit Ticket:Why do you think there are less divisions in Pre- Cambrian time? Please answer in 2-3 sentences.
Homework:● Finish Webquest● Start vocab (quiz
will be next Monday)● Work on Current
Event
Pre-Cambrian Time
● Lasted from 4.5 billion years ag0 until 544 million years ago
● Few Life forms existed at this time○ Single cell organisms, such as CYANOBACTERIA
dominated
● Invertebrates appeared during this time (similar to jellyfish and corals), left trace fossils
● Major geologic events: Earth was cooling● “Cambrian” explosion- rapid spread of inverts
marked the end of the Pre- Cambrian
Paleozoic Era
● 544 million to 248 million years ago● Dominated by invertebrates that lived in oceans
(lots of shelled animals)● First land plants /animals and vertebrates (fish,
reptiles, and amphibians) appear● Several mountain building events, including the
building of the Appalachian Mountains occurred in this era; creation of PANGAEA
● Ended with a mass extinction (cause still debated)
What characteristics of reptiles, allowed them to be the first animals to move away from the water?Protective scaly skin, eggs that could be laid away from water, claws for digging and climbing
Mesozoic Era
● 248- 65 Million years ago● “Age of the Dinosaurs”- dominated by reptiles● Birds, Mammals, and Flowering plants appear
in this era● Major Geologic Events: break- up of Pangaea
and eventual formation of current continents● Ended with a mass extinction, possibly caused
by a comet or meteor striking the Earth
Who survived?
What organisms survived the mass extinction of 65 million years ago?
Cenozoic Era
● 65 million years ago until today● Dominated by mammals● Humans first appear during this time● The Alps, Andes and Himalayan mountains
formed
Speciesa group of organisms that normally reproduces only with other members of their group.
2 members of the same
species – fertile offspring 2 different
species – non fertile offspring
Ex: 2 dogs Ex: a lion and a tiger
Even though 2 organisms look nearly alike, if the
populations they each come from do not interbreed naturally and produce
offspring that can reproduce, the 2 individuals do not belong in the same
species!
Natural Selection
- Charles Darwin – published a book – theory of evolution by natural selection- is a process by which organisms with characteristics that are suited to a certain environment have a better chance of surviving and reproducing than organisms that do not have these characteristics.- organisms compete with each other for resources necessary for life (ex: food, living space)
- differences could hurt or help an organism stay alive(these are called adaptations)
“Survival of the fittest.”
better adapted – live longer, better chance of producing offspringless adapted – shorter life, less chance of producing offspringSo, the better adapted genes are passed on more often.According to Darwin, this cause species to change over time.
Short neck giraffe(rare)
Long neck giraffe(common)
Amount of short neck giraffes has
decreased over time.
Artificial Selection- used by humans to breed animals- carefully choosing individuals with desired characteristics- Can you name three breeds of dog?
Movement of the Continents
Lightly color landmasses these colors on both maps:-North America- Purple- South America- Red-Europe/ Asia- Green- India- Yellow-Africa- Orange- Australia- Brown