From the Italian for "incline", a cuesta is a landform that develops where the local geology consists of gently tilted (formerly horizontal) layers of sedimentary rock. Sedimentary layers that have been more severely tilted form hogback ridges rather than cuestas.

Multiple beds of sedimentary rock invariably contain layers more resistant to erosion than others; these layers, of course form the high points, and protect the rock underneath. When the layers are more or less gently tilted, the resistant layers support long ridges, each with has a steep escarpment on one side, and a gentle slope on the other. Between the ridges, less-resistant rock erodes away to form broad valleys. A cross-section of a cuesta landscape might look like this:

        _                              {_`-._                                           _ 
       {_`-._                          } `-._`-._                                      {_`-._ 
       } `-._`-._~~~~~~.             ,"      `-._`-._~~~~~.                            } `-._`-._
    .~"      `-._`-._   `~~~~~~_~~~~"-._         `-._`-._  `~~~~~~~.                 ,"`-._  `-._`-._~~~~~~.
~~~"             `-._`-._      `-._     `-._         `-._`-._       `~~~~~~__~~~~~~~"`-._  `-._  `-._`-._   `~~~._

Cuestas are invariably eroded by the antecedent drainage systems in place when the landscape began to be uplifted. As the landscape develops, its underlying geology shapes the drainage into a distinctive trellised drainage form. An aerial view of a cuesta landscape can be seen in the trellised drainage node.

As the landscape develops, and subsequent streams excavate the valleys, consequent and would-be consequent streams carve gaps in the ridges. The cuestas are separated into segments resembling long lines of lemon wedges. As the valleys will continue to be excavated, the resistant layers at the tips of the escarpments are undermined and break off. The tips of the resistant layers migrate across the landscape. As long as there is continued uplift (or sea level drop), the valleys will migrate with them. Eventually, however, the ridges will be worn away into nothing.

Cuestas also form around the fringes of large mountain ranges, where horizontal sedimentary layers have been distorted by a nearby area of tectonic uplift.

Cuestas can be found all over the world. Some examples include:

If I missed your favorite cuesta, let me know.

Cues"ta (?), n. [Sp.]

A sloping plain, esp. one with the upper end at the crest of a cliff; a hill or ridge with one face steep and the opposite face gently sloping. [Southwestern U. S.]


© Webster 1913

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