A mountain range is a chain of mountains borered by lowlands or separated from other mountains by passes or rivers. Individual mountains within the same mountain range do not necessarily have the same geology, though they often do; they may be a mix of different orogeny, for example volcanoes, uplifted mountains or fold mountains and may, therefore, be of different rock. The Andes is the world's longest mountain range. The Himalaya contains the world's highest mountains. The Arctic Cordillera is the world's northernmost mountain system and contains the highest point in eastern North America.