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.
Its location near a plate boundary affects the kind of bedrock it has. Under Mount Rainier, there is igneous rock that formed from lava and magma in the Tertiary period, which was between 65 and 1.8 million years ago, intruded by the granodiorite and quartz mononite of Tatoosh pluton.ount Rainier formed along a convergent tectonic plate boundary, where the denser oceanic crust of the Juan de Fuca plate is subducted under the less dense continental crust of the North American plate.