Sediments of Clark Creek

This section illustrates the common types of sediments and sedimentary particles found in the Clark Creek area. The continuous tone photos were obtained with a scanning electron microscope. This instument allows us to magify a sample many times so that we can actually see particles that are smaller than 0.004 mm.

Table of Contents

I. Types of Sedimentary Particles

II. Changes Sediments Undergo


Sand-sized Sediments


This sample shows sand particles in a sediment from the bed of Clark Creek. Sand-sized sedimentary particles have diameters between 2.0 and 0.0625 mm.



In this photograph from Clark Creek, the sand deposits occur in the stream itself. They were deposited when the speed at which the stream was flowing became too slow to retain sand-sized particles in motion. A few coarser particles of gravel are also seen in the upper left area of the photo. Sand in the bottom of the stream is also being reworked by a burrowing organism creating the meandering trails seen throughout this section of the stream.


Silt-sized Sediments

In this sediment sample, the grains are a little smaller than in the sand photos above. They only look bigger due to magnification. Silt-sized sedimentary particles have diameters between 0.0625 and 0.004 mm.


Silt-sized particles are the main components of the Peoria loess that caps the hills in the area.


Clay-sized Sediments

In this sample, the flakey nature of clay-sized sediments is very evident. Clay is the last of the sediments to be deposited by a stream due to its small grain size. Clays have diameters that are smaller than 0.004 mm.


Clays form an easy to recognize layer dissected by erosion in some segments of Clark Creek. These blue sediments are part of the unit called the Pascagoula Clay.



Sedimentary particles are often glued together by cements composed of silica, iron oxides, or carbonates.

Cemented sediments in the Clark Creek area form the erosion resistant layers that are responsible for the waterfalls.




The breakdown of minerals by weathering often forms new minerals such as the hematite shown here.

In the field, hematite often appears as red splotches defining an ancient soil horizon


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