The Great Wall
Traveling is the most exciting thing to me. By traveling around, I increase my knowledge, and it also makes me healthy and strong. Here I would like to talk about one resort that I like most, it’s called Great Wall.
Why to build up the Great Wall? The construction of the Great Wall started during the Warring States Period on 7th century B.C, more than 2,500 years ago. At that time, it was the Warring States Period in ancient China, Many dukedoms built walls in Central China to protect themselves from each other and from the "barbarians" in Mongolia, the walls were built in the states of Qi, Chu, Yan, Han, Zhao, Wei and Qin. The Great Wall was only a regional project to ward off enemies from the north then. However, the separate walls were joined together and consequently stretched from east to west for about 5000 thousand kilometers in Qin Dynasty. The Wall had been further extended and strengthened the succeeding dynasties. Especially in Ming dynasty, the northern nomadic ethnic groups became very powerful, the emperor ordered to renovate the Wall many times to a full length of 6,700 kilometers.
So marvelous it is, and then you may ask:” what’s the Great Wall made of?” In Qin Dynasty (221BC-206BC) or earlier and later, the Great Wall was basically built by stamping earth because of the weapons like swords and spears at a low technology. Neither fortresses were constructed along the wall, nor bricks were used in the construction of gates at the passes. In this period, the wall was made of layers of rammed earth. The section remaining in Gansu Province today is a typical example. Scientists have found that the foundation comprises a layer of raw earth, over 1.5 meters thick at the bottom, with further loess above, some three meters thick. The wall was built on this foundation from layers of tamped-earth. The tamped-earth process began with a simple wooden frame. Workers filled the frame with loose earth, which was then tamped into a compact layer 4 inches thick. The process was repeated layer upon layer, and the wall slowly rose four inches at a time. So you can imagine how long it will take to build a seven-meter high wall. Detritus was mixed into the wall to make it more solid.