Rivers, streams, lakes, and reservoirs aren't just scenic parts of our landscape—they're also vital engines for life on Earth ...

The ozone layer is a part of Earth’s atmosphere that captures ... concentration of roughly 2 to 8 parts per million to form the ozone layer. While oxygen molecules don’t absorb UV radiation ...

Chemical composition of ancient rocks Iron sulfide can only exist in rocks that were formed before there was oxygen in the atmosphere. Rocks containing iron oxide can only form if oxygen is present.

Chemical composition of ancient rocks Iron sulfide can only exist in rocks that were formed before there was oxygen in the atmosphere. Rocks containing iron oxide can only form if oxygen is present.