How Terrains Evolve

Sep. 15, 2016

In the previous article on “When age matters”, I discuss how older GIS data is often sufficient for many uses because most terrain changes gradually over time. In this article, we will look at the major causes of those changes.

Sept._15_blog.jpgGeologic Phenomena: The earth’s crust is always in flux and changing. Plate tectonics describes the movement of the earth’s lithosphere (plates) over time slowly changing the earth’s continents and oceans. Volcanoes are areas where molten rock from the earth’s mantle surface as lava. Most volcanoes occur at plate boundaries. Earthquakes are also associated with tectonic plate boundaries. As the plates move, their edges stick and slip causing an earthquake. Most of these phenomena are slow processes but both earthquakes and volcanos can cause rapid change to a terrain.

Weather & Natural Disasters: Weather conditions such as rain, wind, tornados, and hurricanes cause changes to the topography. Some alterations are due to slow processes such as erosion and weathering while others cause more rapid change such as floods, hurricanes, fires, and tornados. Floods can create new lakes and change the course of rivers and streams. Flooding can also create landslides causing dramatic changes in the elevation of an area. Large wild fires and drought can make an area prone to rapid erosion and landslides when rain and flooding returns.

Man Made Changes: Humans are one of the few species on Earth that can change the environment (terrain) to meet its needs and desires rather than having to adapt to the environment. That is why ocean and space colonization are very real future possibilities. The current annual world growth rate is around 1.13%, which is below the peak rate of 2% during the 1960s. With that said, it is still around 80 million additional people per year we need to make room for. In more populous areas where land is limited, this means building taller buildings and in other areas this means expanding away from the city. All of which requires changes to the land. More people mean more resources from mining, farming, and energy. Man made changes to the Earth are one of the major reasons for rapid terrain changes.

Any type of evolution typically involves time as is the case with terrain changes. But there are certain forces that can cause that evolution to accelerate such as with human intervention, weather, and natural disasters. Understanding the causes of terrain changers helps us as humans better predict and be prepared for those changes. Can you think of other forces that can cause dramatic changes to the Earth’s surface? Add your thoughts and ideas below.

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