1. Geological time, Fossils, & Dinosaurs
Mrs. Green 

2. Bell Work What type of rock is fossils made of?
Take out your activity to finish.

3. Fossils
Fossils = preserved remains or traces of living things and are formed when living things die and are buried by sediment.
Where are fossils found?
Mold – hollow area in the sediment which shows the shape of an organism or part of an organism.
Cast – solid copy of the shape of an organism.
Petrified fossils – fossils in which minerals replace all or part of an organism.
Carbon film – extremely thin coating on rock.
Trace fossils – these provide evidence of the activities of ancient organism

4. Who is a paleontologist?
Paleontologist = a scientist who studies, collects, and classifies fossils.
Information that is gathered by Paleontologist is called Fossil records, which provides evidence of the following:
History of life on Earth
Groups of organism changing over long periods of time
Earth’s past climate
Past environments and changes in Earth’s surface
The Fossil Records also provide evidence to support the theory of Evolution. (we will further discuss this topic later in the school year)

5. Fossil Lab

6. Bell work 12/11/17 1. What is the definition of Geological time?
2. What are 3 types of fossils that we have learned in class? 
3. What is the Law of Superposition?

7. Geological time scale
Earth’s history is divided into units of time that make up a geological time scale which is divided into four major subdivisions:
Eons  the longest subdivisions based on abundance of fossils
Eras  marked by significant worldwide changes in the types of fossils present in rock
Periods  based in types of existing life globally at a particular time
Epochs  divided periods of time characterized by differences in life forms
Scientist hypothesize that Earth formed roughly 4.6 billion years ago.

8. Earth’s Eras
The Phanerozoic Eon is characterized by three eras: (we live in this eon)
The Paleozoic era  the oldest era divided into 6 periods
The Mesozoic era  the middle era divided into 3 periods
The Cenozoic era  the youngest era divided into 2 periods (we are here*)

9. Paleozoic Era  544 – 245 million years ago
Early Paleozoic era consist of the Cambrian and Ordovician periods:
Often called the Age of Invertebrates
Continents were covered by large, shallow inland seas
Middle Paleozoic era consists of the Silurian and Devonian periods:
Often called the Age of Fishes
Some invertebrates lived on land (cockroaches & dragonflies)
The continents start colliding to form mountain ranges
Late Paleozoic era consists of the Carboniferous and Permian periods:
Often called the Age of Amphibians (reptiles evolved from amphibians)
The continental collisions let to the formation of Pangea
A large mass extinction occurred, scientist debate about how and why

10. Mesozoic Era  245 – 65 million years ago
This time period is often called the Age of the Reptiles
This time ear contained the Triassic, Jurassic, and Cretaceous periods.
During those time periods dinosaurs dominated the earth, small mammals and birds also appeared.
Flowering plants appeared as well.
Pangea started to separate into continents, oceans began to form, and dinosaurs could no longer walk across from continent to continent.
At the end of this era a mass extinction occurred from a large meteorite impacting earth.

11. Cenozoic Era  65 million years ago to present
Early in the Tertiary period continents continued to move and collide with one another causing the Himalayas and Alp Mountains.
New grasses and flowering plants dominated the land
Mammals continue to evolve and grow
Homo sapiens, or Humans appear about 400,000 years ago
We live in the Quaternary period of time

12. Determining age of rocks
One way to determine the age of a fossil is by finding the age of the rock it was found in.
Two ways to classify a rocks age:
Relative age – age compared with the age of other rocks
Absolute age – the number of years since the rock formed
Law of Superposition = in horizontal sedimentary rock layers the oldest layer is at the bottom, each higher layer is younger than the layer below it

13. Determining age of rocks
To determine relative age of rocks, geologists also study the following:
Extrusions – is lava that hardens (igneous rocks) on the surface
Intrusions – magma that cools and hardens into a mass of igneous rocks beneath the surface
Fault – a break in Earth’s crust which is always younger than the rock it cuts through
Unconformity – a gap in the geological record where some rock layers have been lost because of erosion

14. Determining age of rocks
Geologist use radioactive dating to determine the absolute ages of rocks, by first determining the amount of a radioactive element in a rock.
Radioactive decay = the process by which one unstable element breaks down into another element that is stable
Half life – the time required for half of the unstable element to decay.

15. Bell work 1. Do rocks age like humans do?
2. When we find fossils in the earth we know immediately that they have to be really old. However, do we know how old they actually