Page 14--Landforms and Landscapes, continued
North of the Cherokee Lowlands is the Osage Cuesta (pronounced kwesta) region.
This area was once covered with shallow seas. During the Pennsylvanian and
Permian periods, about 230 to 310 million years ago, these seas would grow and
shrink due to sea-level changes. The changes were caused in part by
fluctuation in the amount of ice in the polar ice caps. When more of the
Earth's water was frozen at the poles, world-wide sea levels in other areas
would drop. Sometimes the Kansas seas completely disappeared. When some of
the ice at the poles melted and water was released, water levels rose again.
Today the sea level is lower than during the Pennsylvanian and Permian periods
and land in the area has been uplifted, or raised, by changes in the Earth.
Lower sea levels and higher land caused the seas to retreat. The rocks
formed from sediment deposited by the seas were then buried several thousand
feet. Uplift and erosion have now exposed these rocks and formed hills,
Cuestas have a steep slope on one side (an escarpment) and gentler slopes on
the other sides. Cuesta is the Spanish word for cliff.
Figure 32. These cuestas are near Pomona. The arrow points
to a steep slope called an escarpment.
The Osage Cuestas are composed of several alternating layers of sandstone,
limestone, and shale. Not all of the hills in the Osage Cuesta region are
cuestas with escarpments. Rolling hills and flat areas also can be found.
Like all regions in the state, the cuesta region has variety.
West of the Osage Cuestas are the Chautauqua Hills, known for their thick
layers of sandstone and usually densely vegetated with oak and other timber.
During the Pennsylvanian and Permian periods, rivers and streams flowed into
the sea in this area. Sand and other sediment collected at the mouths of the
rivers, forming deltas. When the seas dried up, the sediments were buried
and formed rocks. The sands became sandstone and the muds became shale.
Uplift and erosion eventually exposed sandstone and shale outcrops at the
Figure 33. Orso Falls in Chautauqua County is created where
the Caney River runs over a limestone ledge.
Several glaciers, which are huge masses of ice, covered much of the northern
United States hundreds of thousands of years ago. The glaciers grew and
melted as the climate changed. Most of the glaciers did not reach Kansas,
but at least two dipped down into the northeast corner. When the glaciers
retreated, rocks and soil that had been carried into the area from the north
were left behind. The force of the moving ice was so strong, it broke large
quartzite boulders off outcrops in South Dakota, Iowa, and Minnesota and
carried them over 200 miles into Kansas. The boulders can still be seen
scattered throughout the area today.
Figure 34. Boulders, carried into northeast Kansas by
glaciers, were deposited on a hill near Wamego.
The glaciers also left behind a layer of sediment. Finely ground silt, called
loess, was sorted and carried by the wind. Thick layers of loess were
deposited throughout the area. Fertile soils formed from loess are good
for farming because they contain few rocks.
Kansas Geological Survey
Updated March 4, 1996
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URL = http://www.kgs.ku.edu/Publications/primer/primer14.html