GCBXT03 Loess on the Loose! (Earthcache) in Nebraska, United States created by Ocean5000

GCBXT03 ▼

A cache by Ocean5000 Message this owner

Hidden : 9/9/2026

Difficulty:

Terrain:

Size: Size: other (other)

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Geocache Description:

To claim your find for this EarthCache, please complete the following logging tasks and send your answers to me through Message Center. The goal is to observe and learn from the geology around you, so have fun exploring and answer each question to the best of your ability! You may log the EarthCache immediately after sending your answers; there’s no need to wait for a response from me. If I have any concerns or questions about your answers, I’ll reach out to you

Logging Tasks:

Visit Waypoints 1 and 2. You will observe two different types of mass wasting. Identify the type at each waypoint.
Compare and contrast the mass wasting that occurs at each waypoint.
Walk down to the bank of the stream and take a golf ball-sized amount of soil (or about 25 g) from the stream's edge. Perform the Soil Texture Test as seen in the flow chart above. What type of soil is found in and near the Elmwood Park Creek?
Based on the type of soil that you’ve identified and what you’ve learned in the description, what does this tell you about future erosion occurring at the GZ?
As of June 2019, earthcaches contain required photo logging tasks. Please provide a photo of yourself, your GPSr, or a personal item that proves that you have visited this site. Please post this in your log.

Peoria Loess:

Much of the upland landscape surrounding Omaha is covered by Peoria Loess, a thick deposit of wind-blown sediment. Loess is composed predominantly of silt-sized particles, which are finer than sand but coarser than clay. Rather than being deposited by a river or creek, wind carried this sediment, and it gradually accumulated across the landscape.

Peoria Loess is the younger of the two major loess deposits mapped in the Omaha area and covers much of the land between stream valleys. Beneath it, the older Loveland Loess is exposed in a few locations. Streams have subsequently cut valleys through these deposits, exposing the sediment along slopes and creek banks. Peoria Loess is predominantly composed of fine sediment. Studies of Peoria Loess across Nebraska show that its particle size changes geographically, generally becoming finer from northwest to southeast across the state. Because Omaha lies in eastern Nebraska, the loess found in this region is relatively fine-grained compared with deposits farther west.

Why Does Soil Texture Matter?

Not all soil reacts to flowing water in the same way. Sand, silt, and clay differ in particle size and therefore behave differently when exposed to water. This is why examining the texture of soil along Elmwood Park creek can tell us something about how the creek bank may change in the future.

Sandy soil consists of relatively large particles and generally feels gritty. Silt consists of smaller particles and typically feels smooth or flour-like when dry. Clay contains extremely small particles and becomes sticky and plastic when wet. Most natural soils contain some combination of sand, silt, and clay, which is why terms such as silt loam, loam, sandy loam, and silty clay loam describe soil texture. Of these three particle types, silt is generally the most susceptible to erosion by water. Sand grains are relatively large and heavy, meaning flowing water requires more energy to detach and transport them. Clay particles are much smaller and individually easy to transport once suspended, but the strong cohesive forces between clay particles make them more difficult to detach from an intact soil surface. Silt occupies an erosional middle ground: its particles are small and light enough to detach and be transported by water, but they lack the strong cohesion found in clay-rich soils. As a result, soils containing large amounts of silt can be particularly vulnerable to erosion when exposed to rainfall, runoff, or flowing stream water. This is especially important around Omaha because Peoria Loess is composed predominantly of wind-deposited silt.

At the GZ, you can investigate the soil yourself using the soil texture test shown in the flow chart below. By moistening a small sample and observing whether it forms a ball or ribbon, and whether it feels gritty, smooth, or sticky, you can estimate its texture.

What is Mass Wasting?

Mass wasting is the downslope movement of soil, rock, or debris primarily under the influence of gravity. Although erosion and mass wasting are related, they are not exactly the same process. Flowing creek water can erode and transport sediment, while gravity causes unstable bank material to move downward through mass wasting. There are four main types of mass wasting that can occur: rock falls, landslides, mud slides, and slumping.