3/8 & 3/9 - 7th Grade Agenda Learning Objective: Discuss how the earth was created. Collect HW: Conducting Scientific Investigation Collect HW: Signed Grade Printout Change Job Video: Walking w/ Monsters before Dinosaurs Text Book Reading: 274 – 282 HW: Reading & Notetaking p. 139 -142 Reminder: Last day to take back the Science Fair Board is 3/8 & 3/9

Reflection Prompt: What is an index fossil? How can it help scientists determine age of fossils?

New Jobs

What is an index fossil? Index fossils help geologists match rock layer To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that existed only briefly.

Which fossils are index fossils ? Trilobite Ammonite

These rocks are some of the oldest fossils in the world These rocks are some of the oldest fossils in the world. How old are they? Stromatolites: Remains of ocean reefs created by bacteria more than 3 billion years ago.

What is Radioactive Decay? Radioactive Decay: over time, unstable elements break down or decay by releasing particles and energy.

What is half-life? The half-life of a radioactive element is the time it takes for half of the radioactive atoms to decay.

If Geologic time went by in a single day, when did humans first appear? Humans first appear one second before midnight

Geological Time Scale Paleozoic: Paleo means ancient or early Mesozoic: Meso means middle Cenozoic: Ceno means recent

When was the earth created? Earth was formed about 4.6 billion years ago

When did life began on earth? Earliest forms of life began about 3.5 billion years ago. They were single celled organism similar to bacteria

Development of Atmosphere

What happened during Paleozoic Era 544 – 245 Million Years ago? Cambrian Explosion: At the beginning of the Paleozoic Era, a great number of different kinds of organisms evolved.

Cambrian Period – Explosion of Life in the sea (544 Million Years ago)

Devonian Period – Animals invade the land (408 Million Years Ago)

Permian Period (286 Million Years Ago)

End of the Permian Period, there was a mass extinction – (245 Million years ago) 95% of life in the oceans disappeared What do you think might have cause the mass extinction?