What Is a Cuesta?


The cuesta landform is unique to this region in Kansas. It represents a steep hill on one side and a gentle slope on the other side. In the example of the Osage Cuestas, the limestone makes up the steep hill that is least resistant to weathering while the easily eroded shale creates the gentle slope. All of the cuestas face east in Kansas, but not always the case in other parts of the mid-west. The shales are easily eroded because they are not well consolidated and very platy. Despite this shortcoming, these shales have been well known for producing oil and gas.
An Example of a Cuesta

The source of this material is the Kansas Geological Survey website at KGS Website. All Rights Reserved.


What Caused the Cuestas?



The Osage Cuestas have shown geomorphic changes since the Pennsyvannian and Permian. Cyclotherms, or alternating stratigraphic sequences of marine and non-marine sediments, are well-perserved in the region showing the movement of the sea, but exogenic and endogenic influences have also shaped the landscape.

Endogenic factors that changed the landscape and created the cuestas include plate movement and mountain building in the west and south. This caused the general shift of the stratigraphy to slope towards the east, which is why no cueastas in the area face the west.

Exogenic factors are more readily seen, affect the landscape today. Weather and climate change flucations affect the steepness of the cuestas, which are much more shallow today than in the past. Wind and water erosion deteriorate the shale and sandstone beds more readily leaving the limestone outcrops as the main rock type.

In certain areas the limestone, shale, and sandstone repeating layers can still be seen; they are a direct represenative of the cyclotherms in the area.

Limestone and shale are the most prominent rock types found in the region. The limestones contain fossils which include horn coral and brachiopods.

The sandstones of this region are interpreted as channel deposits that were established after the formation of the Ouachita Mountains, located on the southeastern border of modern day Oklahoma/western border of Arkansas. During the Pennsylvanian period, this was the geologic high point of the time; rain would erode the rocks on the slopes of these mountains, and the sediments would be washed down the stream channels into Kansas.

IF you wish to know more about this area's weather and how it affects the region, visit The Climate and Geomorphology Page
A cuesta

Drawing by James Whittington


What Else Can You Tell Me?


A cuesta region can also be indicated by its flora. Due to the lack of rain some years, the region consists of tallgrass praire, with a mixture of woodlands in the creek and river valleys.

In the maintainence of the tallgrass prairie, an important factor that cannot be dismissed is fire. Both natural and artifical fire cuts back on woodland growth. Without it, the majority of eastern Kansas would be woodland.

In modern times, the weathered shale is incorporated into the soils, and is used in fostering large amounts of farming. The majority of the area is either pastured for cattle, or tilled and farmed for a variety of crops: everything from corn and wheat, to chickpeas and cotton.
Example of Tallgrass Prairie
Photo from Wikipedia