Environment

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What Is Permafrost?

In geology, permafrost refers to ground (rock or soil) that has a temperature of 0 °C (32 °F) or lower for two or more years.

August 1, 2017 18:14

What is a Raptor?

A raptor is a bird that hunts and feeds on other animals.

August 1, 2017 18:14

How Are Rivers Classified?

Rivers are classified on the basis of different factors, including by their physical makeup, speed, and shape.

August 1, 2017 18:14

What Is A Gallery Forest?

Gallery forests exist as a belt along rivers or wetlands and project at the other edge into landscapes that are otherwise only sparsely treed.

August 1, 2017 18:14

US Cities With the Cleanest Air

The following cities were ranked as having the least amount of particle pollution by the American Lung Association.

August 1, 2017 18:14

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