Why has Earth experienced ice age cycles over the past several million years? How do changes to ocean nutrients cause CO2 concentration in the atmosphere to naturally change over the course of an ice age cycle?

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

Gemstones are commonly found in pegmatites, which are igneous rocks that are a. exceptionally mafic b. exceptionally coarse grained c. exceptionally fine grained d. extrusive, forming from lava

People make choices about how to use resources.