May 16th, 2012
An incised meander on the Colorado River, Utah.
Wait, what is an incised meander I hear you say? It’s a landform of river rejuvenation. River rejuvenation occurs when either the global sea levels fall (Eustatic fall), or the local land level rises (Isostatic uplift) - either way meaning that the river has now risen above the base level even in the lower course. With its renewed potential erosive energy, the river cuts down into the rock beneath it, attempting to reach the base level once more. The river adjusts to its new base level first in the lower reaches, then progressively inland.
As the river erodes vertically, it creates new landforms, namely knick points, incised meanders and river terraces. A knick point is simply the point at which the rivers old profile meets with the new - usually in the form of a waterfall. One of the best examples of this is Skógafoss in Iceland. River terraces are remnants of former flood plains which have been left high and dry as the river eroded down to the new base level, the Grand Canyon is one. Incised meanders follow the same principle - deepened meanders due to the river cutting downward. There are two types however, ingrown and entrenched. The first, as attractive as it sounds, is the product of a combination of both vertical and lateral erosion whilst entrenched meanders are born from pure vertical power. Obviously, the Colorado river pictured above has some, but closer to home, the River Wear in Durham sports several.

An incised meander on the Colorado River, Utah.

Wait, what is an incised meander I hear you say? It’s a landform of river rejuvenation. River rejuvenation occurs when either the global sea levels fall (Eustatic fall), or the local land level rises (Isostatic uplift) - either way meaning that the river has now risen above the base level even in the lower course. With its renewed potential erosive energy, the river cuts down into the rock beneath it, attempting to reach the base level once more. The river adjusts to its new base level first in the lower reaches, then progressively inland.

As the river erodes vertically, it creates new landforms, namely knick points, incised meanders and river terraces. A knick point is simply the point at which the rivers old profile meets with the new - usually in the form of a waterfall. One of the best examples of this is Skógafoss in Iceland. River terraces are remnants of former flood plains which have been left high and dry as the river eroded down to the new base level, the Grand Canyon is one. Incised meanders follow the same principle - deepened meanders due to the river cutting downward. There are two types however, ingrown and entrenched. The first, as attractive as it sounds, is the product of a combination of both vertical and lateral erosion whilst entrenched meanders are born from pure vertical power. Obviously, the Colorado river pictured above has some, but closer to home, the River Wear in Durham sports several.