عنوان مقاله [English]
نویسنده [English]چکیده [English]
The surface of the earth is not completely flat at any point except on the floor of seasonal and temporal lakes that have been dried out due to evaporation of water, such as the small expanses found in the central parts of Iran which are called “Dagh” in the local language. Apart from these very narrow areas we observe that the mountains tall and short, low-lying hills and extensive plains with low or high slopes have covered the surface of the earth. What we see as mountains or hills on the surface of the earth is called “terrace” in geographical terms, and these terraces are divided into two major parts. One is caused by volcanoes, like the conic Mount. Damavand to the northeast of Tehran and thousands of other volcanic peaks that are scattered across the earth. All volcanic peaks of the world have been created in the form of tremendous eruptions due to the penetration of the earth’s internal molten material to the outside. In addition to these peaks, the molten material occasionally flows out of huge gaps and covers a large area that may reach several thousand square kilometers by thick layers of interior materials called basalt. The other ones that have come to existence due to folds have here been inevitably referred to in terms of their mechanism of appearance.