After World War II, the map of Europe was almost completely redrawn. Political boundaries change over time through wars, treaties, and trade. Sometimes, political boundaries follow physical boundaries, but most of the time you can’t see them. These lines, more often called borders, are created by people to separate areas governed by different groups. Political boundaries are the dividing lines between countries, states, provinces, counties, and cities. state of California prone to earthquakes. The transform fault between the Pacific and North American plates makes the U.S. The convergent boundary between the Pacific and Australian plates makes the island nation New Zealand a very active volcanic region. The divergent boundary between the Cocos and Nazca plates creates the Galapagos Ridge, off the coast of South America. This tectonically active area is called the Ring of Fire. The movement between the massive Pacific plate and the plates that border it creates all three types of boundaries. This is called a transform fault or transform boundary. Sometimes the plates grind past each other, creating earthquake fault lines. This is called a convergent plate boundary. Sometimes one plate slides underneath the other, creating volcanoes and earthquakes. Sometimes, the plates spread apart from each other, creating ocean trenches and, eventually, continents. Interaction between tectonic plates creates activity on their boundaries. There are seven major tectonic plates and many smaller ones. Earth’s shell, or crust, is made of thick slabs of rock called tectonic plates. The Mississippi River is the defining boundary between many of the states it winds through, including Iowa and Illinois, Arkansas and Tennessee, and Louisiana and Mississippi.Īnother type of physical boundary lies below Earth’s surface. The Rio Grande forms a large part of the boundary between Mexico and the United States. Rivers are common boundaries between nations, states, and smaller political units such as counties. This narrow waterway between the Atlantic Ocean and the Mediterranean Sea is an important political, economic, and social boundary between the continents. The Strait of Gibraltar is the boundary between southwestern Europe and northwestern Africa. For example, the boundary between France and Spain follows the peaks of the Pyrenees Mountains, while the Alps separate France from Italy. Many times, political boundaries between countries or states form along physical boundaries.
Rivers, mountain ranges, oceans, and deserts can all serve as physical boundaries. A physical boundary is a naturally occurring barrier between two areas. The most obvious type of boundary is a physical boundary.
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