Friday, 30 August 2013

Colonisation of the US

European colonisation of the Americas began as early as the 10th century (Vikings, Norse sailors) 

Extensive European colonisation began in 1492, when a Spanish expedition headed by Christopher Columbus sailed west to find a new trade route to the Far East but inadvertently found the Americas. European conquest, large-scale exploration, and colonization soon followed. 

The next map shows the European claims in America in 1750.

When the United States won its independence from Great Britain at the end of the Revolutionary War, the country nearly doubled in size. 

After 1783, the United States gained new land from European countries, neighboring countries (such as Mexico), and Indian tribes. This was done through purchases (paying for it), wars and treaties, and the forced removal of Indian tribes from the lands they had occupied for thousands of years.

The 13 original British colonies became the country's first states, but they were not the same size and shape as they are today. It took more than 176 years — from 1783 to 1959 — for all 50 states to become part of the United States of America.

Tuesday, 13 August 2013

Exogenetic process

The exogenetic processes are the processes that shape the land by forces coming on or above the Earth's surface (exogenetic forces).

For example: 
  • The Moon causes tides in the Earth's oceans and other big bodies of water (as a result of other bodies in space). 
  • Impacts from comets and meteoroids change the surface of the Earth. When they strike the Earth, they create craters which are holes, which can be very big or small, in the ground (as a result of other bodies in space).
  • Radiation from the Sun can cause aurorae, which are lights that can be seen at night near the poles (as a result of other bodies in space).
  • An example of an exogenetic process that is not as a result of bodies in space is erosion. Erosion happens as a result of wind, water, ice, or people, animals, or plants digging in the earth.

Endogenetic process

The endogenetic processes are the processes that shape the land by forces coming from within the earth (endogenetic forces). Endogenetic process is also called endogenic process. 

There are 3 main endogenetic processes: 

  • folding, 

  • faulting and 

  • volcanism. 

They take place mainly along the plate boundaries, which are the zones that lay on the edges of plates. These zones are weak. Endogenetic processes cause many major landform features.

Monday, 12 August 2013

The Grand Canyon

The Grand Canyon is a famous, steep-sided canyon carved by the Colorado River in the United States in the state of Arizona. The Grand Canyon is considered one of the Seven Natural Wonders of the World. The Grand Canyon became a national monument in 1908, but wasn't designated as a national park until 1919.

The Grand Canyon is 446 km long, up to 29 km wide and attains a depth of over 1,800 meters.
Nearly two billion years of the Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted by tectonic action.

Evidence suggests the Colorado River established its course through the canyon at least 17 million years ago. Since that time, the Colorado River continued to erode and form the canyon to the point we see it at today.

Many people come from around the world to visit the Grand Canyon. People can also take trips floating on the Colorado River in boats and rafts. Some people like to hike in the Grand Canyon.