What are Gorges?
New River Gorge, USA
Name of Landform: 'Gorge' is the French word for throat or neck. They are often referred to as canyons, ravines, or valleys but these alternate names, however, are not the equivalent landform of a gorge. A gorge is typically any narrow or deep valley between tall slabs of steep rock on either side and has a source of water flowing through the bottom of the valley.
Description: As stated above a gorge is a narrow valley or ravine between two rocky walls that are usually mountains or hills. There is usually a river or some stream of water that flows down the middle at the bottom of the valley. Gorges, valleys, and canyons can be quite similar but their characteristics, composition, the ways in which they are created and where (the regions) make the difference in name. For example gorges are typically smaller in size, far more narrow, and much steeper than canyons. As well, canyons do not always have to have a stream of water moving across the bottom of the ravine as gorges usually do.
Formation: Gorges are the result of erosion and geological uplift over long periods of time. When streams or rivers flow through mountains, they break away and wear down the rock, also tearing away sediments of rock. In other words, moving sources of water are able to erode the rock until it becomes the steep and narrow walls of a gorge. Interestingly, lava flow can also create gorges much like water does! Geological uplift is defined as the vertical elevation of the Earth's crust or surface. This could be the movement of crusts rising over or under each other (forming mountains) or it could be the natural force of fault lines that cause collisions of crusts, resulting in a vertical elevation or uplift of the Earth's surface. This uplifting of land allows for the water to be lifted as well and continue eroding the rock away from a mountain. Moreover, as the water continues to flow over the uplift, it forms a waterfall. With the speed and power of the waterfall breaking down the rock continually and consistently, eventually the softer layers of rock collapse, forming a gorge. A less common method of the formation of gorges is through glaciers and glacier movement. When glaciers scrape across the Earth, they can create deep valleys in the surface and thus forming a narrow and sharp gorge.
Association: Gorges are often found with other sensational landforms around it and are often classified with many similar landforms as well. Gorges usually appear in mountainous areas and they are typically found as a ravine or very steep valley between two mountains. They are also associated with hills because it is not uncommon for gorges to be cut from hills lush with forests. Usually, a river or stream flows down the middle at the bottom of the gorge and it would move downstream. Also, most gorges are made up of granite, sandstone, and limestone in composition. Sometimes, fossils can be found buried in the layers of rock that hold the walls of the gorge. They are also found everywhere on the planet, so long as there are mountain ranges or hills. In addition, they can appear in almost any climate, from areas where volcanoes are active (Werribee River Volcanic Gorge, Australia) to regions where the temperature allows for glaciers to be present all-year round (Glacier Gorge Grindelwald in Switzerland).
Age: The layers of rock inside gorges are estimated to be around 2 million years old, formed during the Cenozoic era. However, the cutting of gorges with rivers and channels of water is estimated to have taken anywhere from 3 million to 320 million years (between the Cenozoic and the Paleozoic era), depending on the gorge and its location. For example the New River Gorge in the United States is estimated to have been formed in the Paleozoic era and the Olduvai Gorge in Tanzania contains rock layers of approximately 2 million years old. Geologists have yet to find a more narrow range numerically to date the varying ages of the gorges created.
Location: Gorges can be found almost anywhere in the world, so long as that region or area contains uplifted land of hills or mountains. Where there are fault lines and movement of the crust, there are mountains or some type of vertical elevation of the Earth's surface. In these places, with the combination of a channel (or bod) of water that is dynamic, there are likely formations of gorges. Across the globe, there are examples of different gorges and their physical locations truly represent the varying places and regions in which they are found! (See 'Touring Gorges' for a virtual, global inventory of different gorges around the world.)
Description: As stated above a gorge is a narrow valley or ravine between two rocky walls that are usually mountains or hills. There is usually a river or some stream of water that flows down the middle at the bottom of the valley. Gorges, valleys, and canyons can be quite similar but their characteristics, composition, the ways in which they are created and where (the regions) make the difference in name. For example gorges are typically smaller in size, far more narrow, and much steeper than canyons. As well, canyons do not always have to have a stream of water moving across the bottom of the ravine as gorges usually do.
Formation: Gorges are the result of erosion and geological uplift over long periods of time. When streams or rivers flow through mountains, they break away and wear down the rock, also tearing away sediments of rock. In other words, moving sources of water are able to erode the rock until it becomes the steep and narrow walls of a gorge. Interestingly, lava flow can also create gorges much like water does! Geological uplift is defined as the vertical elevation of the Earth's crust or surface. This could be the movement of crusts rising over or under each other (forming mountains) or it could be the natural force of fault lines that cause collisions of crusts, resulting in a vertical elevation or uplift of the Earth's surface. This uplifting of land allows for the water to be lifted as well and continue eroding the rock away from a mountain. Moreover, as the water continues to flow over the uplift, it forms a waterfall. With the speed and power of the waterfall breaking down the rock continually and consistently, eventually the softer layers of rock collapse, forming a gorge. A less common method of the formation of gorges is through glaciers and glacier movement. When glaciers scrape across the Earth, they can create deep valleys in the surface and thus forming a narrow and sharp gorge.
Association: Gorges are often found with other sensational landforms around it and are often classified with many similar landforms as well. Gorges usually appear in mountainous areas and they are typically found as a ravine or very steep valley between two mountains. They are also associated with hills because it is not uncommon for gorges to be cut from hills lush with forests. Usually, a river or stream flows down the middle at the bottom of the gorge and it would move downstream. Also, most gorges are made up of granite, sandstone, and limestone in composition. Sometimes, fossils can be found buried in the layers of rock that hold the walls of the gorge. They are also found everywhere on the planet, so long as there are mountain ranges or hills. In addition, they can appear in almost any climate, from areas where volcanoes are active (Werribee River Volcanic Gorge, Australia) to regions where the temperature allows for glaciers to be present all-year round (Glacier Gorge Grindelwald in Switzerland).
Age: The layers of rock inside gorges are estimated to be around 2 million years old, formed during the Cenozoic era. However, the cutting of gorges with rivers and channels of water is estimated to have taken anywhere from 3 million to 320 million years (between the Cenozoic and the Paleozoic era), depending on the gorge and its location. For example the New River Gorge in the United States is estimated to have been formed in the Paleozoic era and the Olduvai Gorge in Tanzania contains rock layers of approximately 2 million years old. Geologists have yet to find a more narrow range numerically to date the varying ages of the gorges created.
Location: Gorges can be found almost anywhere in the world, so long as that region or area contains uplifted land of hills or mountains. Where there are fault lines and movement of the crust, there are mountains or some type of vertical elevation of the Earth's surface. In these places, with the combination of a channel (or bod) of water that is dynamic, there are likely formations of gorges. Across the globe, there are examples of different gorges and their physical locations truly represent the varying places and regions in which they are found! (See 'Touring Gorges' for a virtual, global inventory of different gorges around the world.)