1. what was unusually abundant in the earth's atmosphere during the
carboniferous period?
what effect did that have on insects?
what was responsible for this abundance?

What major factors play a role in global warming? 1. human activity and normal climate conditions 2. natural factors and human activity 3. normal climate conditions and abnormal human activities 4. abnormal human activities and natural factors

Which of the following describes what rocks usually are composed of ,

How can minerals crystallize from materials dissolved in water? check all that apply.