Good Morning! 1. Complete your warm-up: What happens at a convergent boundary? Be specific. 2. Have out your Venn Diagram. You may have it pasted in your notebook, I am coming around to check for completion. 3. Copy tonight’s HW: Matching half sheet 4. Read silently.

10 minutes to finish your chart.

A Trip Through Geologic Time NOTE: Under “Kinds Of Fossils” you need to ADD Trace Fossil.

Fossils Fossils are traces or remains of ancient life. Fossils show how life has changed over time. Scientists who study fossils are paleontologists.

Fossils Fossils are usually found in sedimentary rocks.

Kinds of Fossils Petrified Wood: stone fossil of a tree.

Kinds of Fossils Molds and Casts Mold: is a hollow area in the shape of an organism. Cast: is a copy of the shape of an organism.

Kinds of Fossils Carbon Films: an extremely thin coating of carbon on rock; shows the soft parts of the organism. Trace Fossils: evidence of the activities of ancient life. Ex: footprints, animal trails, feces, or animal burrows.

Kinds of Fossils Original Remains actual body parts of an organism. May form in ice (best preserver), amber (sap), or tar.

Why Study Fossils? 1. To learn what past life forms were like. 2. To classify organisms in the order in which they lived. 3. All the fossils found on earth make up the fossil record.

Fossil Record Provides evidence about the history of life on Earth. Shows how different groups of organisms have changed or evolved; while others became extinct.

Remember! The fossil record is incomplete; most organisms do not become fossils.

Other evidence show change in life and the environment Tree Rings- show weather patterns Ice Cores- show how the atmosphere has changed over time

Finding the Age of Rocks Through Rock Dating

ROCKROCK DATINGDATING

Ages of Rocks The relative age of a rock is its age compared to other rocks. Use words like: “older or younger” The absolute age of a rock is the number of years since the rock was formed. Ex: mya

Rock Joke!! What does a rock want to be when it grows up? A Rock Star!!

The Position of Rock Layers It can be difficult to determine a rocks absolute age. So… scientists use the law of superposition. According to the law of superposition, in horizontal sedimentary rock layers the oldest layer is at the bottom. Each higher layer is younger than the layers below it.

Rock Joke!! How do rocks wash their clothes? The Rock Cycle!!

Other Clues to Relative Age Clues From Igneous Rock Lava that cools at the surface is called an extrusion. Rock below an extrusion is always older. Magma that cools beneath the surface is called an intrusion. An intrusion is always younger than the rock layers around and beneath it.

Other Clues to Relative Age Faults (a break in the rock) are always younger than the rock it cuts through! Unconformities: An unconformity is a gap in the geological record. New rock forms on top of eroded rock

Using Fossils to Date Rocks! Scientists use index fossils to match rock layers. An index fossil must be widely distributed and represent a type of organism that existed only briefly. They tell us relative age of the rocks

The Trilobite One example of an index fossil is a trilobite. Trilobites were a group of hard-shelled animals whose bodies had three distinct parts. They evolved in shallow seas more than 500 million years ago.

Fossil Study Guide