describe in detail the importance of any two continents
Answers
Answer:
Explanation:
Zealandia Microcontinent
A map of elevation and ocean depths, or bathymetry, reveals the microcontinent of Zealandia. Zealandia broke away from the continents of Australia and Antarctica millions of years ago. The light blue color depicts a large continental shelf of shallow ocean extending to the southeast of Zealandia's largest land masses, the South and North islands of New Zealand, and northwest towards the islands that make up New Caledonia.
Building the Continents
The Earth formed 4.6 billion years ago from a great, swirling cloud of dust and gas. The continuous smashing of space debris and the pull of gravity made the inside of Earth heat up. As the heat increased, some of Earth’s rocky materials melted and rose to the surface, where they cooled and formed a crust. Heavier material sank toward Earth’s center. Eventually, the earth came to have three main layers: the core, the mantle, and the crust.
Gradually, the igneous rock built up into small volcanic islands above the surface of the ocean. Over time, these islands grew bigger, partly as the result of more lava flows and partly from the buildup of material scraped off descending plates. When plates carrying islands subducted, the islands themselves did not descend into the mantle. Their material fused with that of islands on the neighboring plate. This made even larger landmasses—the first continents.
Wandering Continents
If you could visit Earth as it was millions of years ago, it would look very different. The continents have not always been where they are today. About 480 million years ago, most continents were scattered chunks of land lying along or south of the Equator. Millions of years of continuous tectonic activity changed their positions, and by 240 million years ago, almost all of the world’s land was joined in a single, huge continent. Geologists call this supercontinent Pangaea, which means “all lands” in Greek.
The positions of the continents are always changing. North America and Europe are moving away from each other at the rate of about 2.5 centimeters (one inch) per year. If you could visit the planet in the future, you might find that part of the United States's state of California had separated from North America and become an island. Africa might have split in two along the Great Rift Valley. It is even possible that another supercontinent may form someday.
Continental Features
The surface of the continents has changed many times because of mountain building, weathering, erosion, and build-up of sediment. Continuous, slow movement of tectonic plates also changes surface features.
The Canadian Shield makes up about a quarter of North America. For hundreds of thousands of years, sheets of ice up to 3.2 kilometers (two miles) thick coated the Canadian Shield. The moving ice wore away material on top of ancient rock layers, exposing some of the oldest formations on Earth. When you stand on the oldest part of the Canadian Shield, you stand directly on rocks that formed more than 3.5 billion years ago.
North America
North America, the third-largest continent, extends from the tiny Aleutian Islands in the northwest to the Isthmus of Panama in the south. The continent includes the enormous island of Greenland in the northeast. In the far north, the continent stretches halfway around the world, from Greenland to the Aleutians. But at Panama’s narrowest part, the continent is just 50 kilometers (31 miles) across.
South America
South America is connected to North America by the narrow Isthmus of Panama. These two continents weren’t always connected; they came together only three million years ago. South America is the fourth-largest continent and extends from the sunny beaches of the Caribbean Sea to the frigid waters near the Antarctic Circle.
South American rainforests contain an enormous wealth of animal and plant life. More than 15,000 species of plants and animals are found only in the Amazon River basin. Many Amazonian plant species are sources of food and medicine for the rest of the world. Scientists are trying to find ways to preserve this precious and fragile environment as people move into the Amazon basin and clear land for settlements and agriculture.
Europe
Europe, the sixth-largest continent, contains just seven percent of the world’s land. In total area, the continent of Europe is only slightly larger than the country of Canada. However, the population of Europe is more than twice that of South America. Europe has more than 40 countries and many of the world’s major cities, including London, the United Kingdom; Paris, France; Berlin, Germany; Rome, Italy; Madrid, Spain; and Moscow, Russia.