The prehistory of the United States started with the arrival of Native Americans before 15,000 BC. Numerous indigenous cultures formed, and many disappeared before 1500. The arrival of Christopher Columbus in the year 1492 started the European colonization of the Americas. Most colonies were formed after 1600, and the early records and writings of John Winthrop make the United States the first nation whose most distant origins are fully recorded.[1] By the 1760s, the thirteen British colonies contained 2.5 million people along the Atlantic Coast east of the Appalachian Mountains. After defeating France, the British government imposed a series of taxes, including the Stamp Act of 1765, rejecting the colonists' constitutional argument that new taxes needed their approval. Resistance to these taxes, especially the Boston Tea Party in 1773, led to Parliament issuing punitive laws designed to end self-government in Massachusetts. Armed conflict began in 1775. In 1776, in Philadelphia, the Second Continental Congress declared the independence of the colonies as the United States.
The internal structure of Earth is layered in spherical shells: an outer silicate solid crust, a highly viscous asthenosphere and mantle, a liquid outer core that is much less viscous than the mantle, and a solid inner core.
