Thursday, February 28, 2013

Pangaea Puzzle

Have you ever been looking at a globe or a map of the earth and noticed how much the coastlines of the continents resemble each other? Wegener's hypothesis described a process where all the continents were once joined into one large piece of land, and over millions of years, were separated into the continents we have today. The hypothesis described a process called continental drift.

In 1912 a German meteorologist named Alfred Wegener (1880-1931) hypothesized a single proto-supercontinent that divided up into the continents we now know because of continental drift and plate tectonics. This hypothesis is called Pangaea because the Greek word "pan" means "all" and Gaea or Gaia (or Ge) was the Greek name of the divine personification of the Earth. Pangaea, therefore, means "all the Earth."

The idea of Panthalassa (all the sea) also given, around the single protocontinent or Pangaea, there single ocean. More than 2,000,000 years ago, in the late Triassic Period, Pangaea broke apart. After noting that the shapes of the continents almost seemed to fit together like a puzzle, Wegener suggested it must have been connected into one landmass. Then he proposed that the enormous, single continent divided into smaller chunks and spread apart due to drifts. Although Pangaea is an hypothesis, the idea that all the continents once formed a single supercontinent makes sense when you look at the shapes of the continents and how well they essentially fit together.

Scientists have studied this idea over many decades, and have found evidence to support Wegener's hypothesis. For instance, fossils of the same plant and animal species found on the east coast of South America have been found on the west coast of Africa. The same types and formations of rocks on the coastline of one continent often match up with the rocks on a continent across the ocean.

According to the theory of plate tectonics, Pangaea later broke up into Laurasia and Gondwanaland, which eventually broke up into the continents we know today. Gondwanaland and Laurasia separated from Pangaea  at the end of the Paleozoic Era and broke up into the current continents in the middle of the Mesozoic Era. Gondwanaland incorporated present-day South America, Africa, Arabia, Madagascar, India, Australia, and Antarctica. Laurasia mass the Northern Hemisphere that included North America, Europe, and Asia (except India).

When you look at the coastlines of Africa and South America, they look as if they fit together, like puzzle pieces! The evidence scientists have found indicates it may be more than a coincidence. The concept of one single continent called a 'supercontinent'. Pangaea was not the first supercontinent believed to have existed. Five million years before Pangea existed, there was another supercontinent they call Rodinia. Rodinia hypothesis is still in observation phase.

Why was the Pangaea hypothesis rejected?

1. They rejected it because from the calculated strength of the rocks, it did not seem possible for the crust to move in this way.

2. Because it obviously had no proof and the same results were not achieved when the experiment was repeated several times by different scientists.

1 comment:

  1. interesting post Mugdha.. We read little bit about this in school book but not in detail like here you have written with wonderful images and examples.