Major Events in Earth's History 1

What division of time was the longest ?

• Paleozoic

• Mesozoic

• Cenozoic

• Precambrian

What era did dinosaurs go extinct ?

• Paleozoic

• Mesozoic

• Cenozoic

What is the geological time scale ?

• A clock

• A calendar

• Something that divides Earths history into groups

When was Earth's land mostly covered in ice ?

• Paleozoic

• Precambrian

Based on the geologic time scale, how old is the Earth?

• 4.5 billion years ago or 4,500 mya
• 3.5 billion years ago or 3,500 mya
• 9 billion years ago or 9,000 mya
• 7 billion years ago or 7,000 mya

A unit of geologic time that subdivides eras

• period
• time span

Scientists chose where units of geologic time began on major changes in ______________ at certain times.

• life forms
• events

What eon are we living in?

• Phanerozoic 
• Precambrian
• Paleozoic
• Triassic

Based on the GTS, when did the first flowering plants appear?

• Cretaceous Period
• Triassic Period
• Cambrian Period
• Devonian Period

What event occurred 3.5 billion years before the present?

• Earth forms

• Human ancestors appear

• Dinosaurs become extinct

• Cyanobacteria fossils appear