Precambrian Earth Study Guide

The oldest rocks on Earth are_______________.

• 1.6 million years old
• 3.5 million years old
• 1-2 billion years old
• 3.8 to 3.96 billion years old

Minerals with low densities crystallize from magma at _____________ denser minerals do.

• always 10 degrees less than
• cooler temperatures than
• hotter temperatures than
• the same temperature as

What was the original composition of earth's atmosphere?

• ammonia
• nitrogen
• water vapor
• hydrogen and helium

Which type of cell existed first?

• Prokaryote
• Eukaryote

What process is primarily responsible for the formation of Earth's oceans?

• sea-floor spreading
• evolution
• outgassing
• plate tectonics

Why don't Archean and proterozoic rocks have iron oxides?

• too much iron around
• no iron existed
• stromatolites were taking over the world
• no free oxygen

How were asteriods and meteorites a heat source for Precambrian earth?

• gravitational contraction by them generated cooling
• their radioactive decay of isotopes made energy
• their impact on Earth generated energy
• they sank to the core

What was the composition of Earth's first crust?

• feldspar, quartz and mica
• feldspar
• iron and quartz
• iron and magnesium rich minerals

What continent existed around 1.8 billion years ago that now forms the core of modern North America?

• Pangaea
• Laurentia
• Rodinia
• North America

What did organisms of earth's first 4 billion years have in common?

• multi-celled
• single-celled
• mammals
• breathed oxygen