Which of the following best defines the term atmosphere?
a. air surrounding the earth
b. life beneath the earth's surface
c. life in the tree roots
d. oceanic life

Explain: plate tectonics and people.

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

Which season has the least amount of rain in the northern latitudes