KANSAS RIVER
What makes the Kansas River different from many other rivers?
The Kansas River flows through what is known as the Stable Interior region. Since this region is near the center of the North American Plate, it has not experienced any extensive geologic faulting, folding, or mountain building in recent geologic time. From the confluence at Junction City, the river flows through limestone, shale, mudstone, and occasional sandstone strata that, except for diagenesis, remain largely undisturbed since deposition in shallow Carboniferous and Permian seas. The age of the rock exposed by the river becomes progressively older as the river moves downstream for two main reasons. First, downstream areas experience more erosion from increased flow, and second because the slight uplift of the Ozark dome to the southeast caused the strata in Kansas to dip very slightly to the west. The Smoky Hill River and Republican River tributaries reach far to the west into the Cretaceous deposits of the Western Interior Seaway and the Neogene Period deposits of material from the uplift of the Rocky Mountains, which created the Ogallala Formation.
All of the rocks in the eastern Kansas valley are sedimentary, ranging from Late Pennsylvanian (300 million years ago) through the Permian, with three notable exceptions from the Quaternary Period. The first is river sand and gravel deposits, which have been carried in largely from erosion of the Ogallala and Cretaceous rocks by the western extents of the Kansas River tributaries. Second, the retreat of the Kansan glaciation left behind a combination of ice- and meltwater-deposited sediments known as drifta, a poorly sorted mixture of clay, sand, gravel, and even large boulders that cover parts the Kansas River basin from the Big Blue River and eastward. The third is loess, a fine silt that may have originally been deposited by the melting water of the receding glaciers, then redeposited by the wind. The thickest loess deposits can be found in the northwest and north-central part of the Kansas River basin from southern Nebraska into northwest Kansas, as well as near the river's mouth.
QUESTIONS/TASKS:
1. Based on the required reading, this river is different than most due to not experiencing geologic faulting and remaining largely undisturbed. What else has it not experienced and it is undisturbed due to it flowing through what?
2. Do you see signs of erosion here and if so what indications of erosion do you see?
3. Investigate the river bank around ground zero. What classification of rock do you see?
4. How do you suppose the sediments here came to be here?
5. To prove that you were here, please post a picture of yourself or your GPS with the river in the background. Any other photos of the area are also greatly appreciated.