Definition of atom. 1  1a : the smallest particle of an element that can exist either alone or in combination an atom of hydrogenb : the atom considered as a source of vast potential constructive or destructive energy â¦ a largely forgotten legacy of this country's conquest of the atom.
The mountain, a part of the Cascade Range, is a volcano that has not erupted for 2,000 years. It is also the highest mountain in the state of Washington. English explorer George Vancouver named Mount Rainier in honor of another navigator, Peter Rainier. Some people, however, prefer to call the mountain by its Indian name, Mount Tacoma.
Much of Mount Rainier is composed of andesite lava flows. Lava flows may accompany explosive eruptive activity, but they occur more often after explosive activity declines.The term andesite refers to the chemical composition of the rock.he only lava flows known to have been erupted from Mount Rainier in the past 10,000 years are those that built the summit cone, which was constructed within the past 5,600 years.