Boundaries between the continents of Earth Boundaries between the continents of Earth The boundaries between the continents of Earth are generally a matter of geographical convention. Several slightly different conventions are in use. The number of continents is most commonly considered seven but may range as low as four when the Americas and Afro-Eurasia are each considered a single continent. According to the definition of a continent in the strict sense, an island cannot be part of any continent, but by convention and in practice most major islands are associated with a continent. There are three overland boundaries subject to definition: While the isthmus between Asia
Middle-earth primeval epoch. The Valar left Middle-earth and went to the newly formed continent of Aman in the west, where they created their home called Valinor. To discourage Melkor from assailing Aman, they thrust the continent of Middle-earth to the east, thus widening Belegaer at its middle and raising five major mountain ranges in Middle-earth which adopted a relatively symmetrical distribution, namely the Blue, Red, Grey, Yellow Mountains and the Mountains of the Wind. This act, however, ruined the symmetry of the shape of the continents and their intervening seas. Many centuries after Valinor was established, Melkor raised the Misty Mountains