A Powerful Stream

This cache was brought to you with the help of the geoslider that likes rocks, fossils, and everything geological. It is in the small Ashford Glen Preserve, nestled between the roads of a development and property that is owned by the Latham Water District. Please respect the area as the stewards of this preserve have had to deal with vandals in the past. Stay on the trails as long as you can and do your best not to create any herd paths.

For this Earthcache you will need to read the information below an, using your own skills of interpretation, find the correct areas, do a couple of calculations and offer your best educated guess at some questions. There are no signs to find for the answers – just read, learn and do. Part 2 involves some significant terrain that must be done carefully, hence the terrain rating.

Please note that there are two parts to this Earthcache. To claim this cache you will need to do all five parts.

Most of us are familiar with how stream erosion works. We know that the scale can be small or amazingly large, such as Grand Canyon. This Earthcache will show you two stages of stream erosion.

In a stream, water flows the fastest at the outside bends and the slowest on the interior bends. As it flows along the outside bend it erodes away soil, small rocks and other particles. Over time, the outside bend is eroded into a “river cliff” which is visible at this locale. Also, over time the river deposits material along the inside bends – this is also evident at this locale.

As the river continues to erode its outer banks and deposit along its inner banks, it begins to “meander”. Meandering is the classic snake like river shape commonly seen in many river environments. The erosion and deposition continue and new areas of bank are formed while the outside bend is eroded to the point where only a small neck of land is left separating the two channels.

Eventually, typically during a flood event, the small strip of land is broken through and an island area is created. You can see this process at work at this locale as well – the neck is still present and you can see where the island will be.

The last stage is where the oxbow has finally formed. Now that the river has a straight path to follow (path of least resistance) it no longer flows through the curved portions of the river. As it flows through the straight channel it deposits soil and debris along the banks. This deposition eventually cuts off the old meandering portion of the river and forms an Oxbow Lake. Oxbow Lakes often fill in over time and are only seen with water during flood events.

Here is a picture demonstrating the steps described above:

So, now you have some background – how do you earn a smiley? Answer the following three questions for the first part and the two questions for the second part.

1. Locate a river cliff section (more of a stream cliff here), take a picture of it and upload the picture with your log
2. Locate an area of deposition, take a picture of it and upload it with your log
3. Determine how long it may take for the stream to cut through and form an oxbow. To simplify this calculation, we will assume that the flow of the river erodes the banks at a rate of 6 cm per year. Use this to determine how long it will take (measure the current width/6cm)

Stream/Rivers go through typical life cycles just like the rest of us. For a stream, the cycle happens over and over again throughout time. Although Geologists argue about certain portions of the life cycle, the general stages are:

Stage 1: In the beginning a stream has a sharp, deepening V-shaped valley, there may be waterfalls and/or rapids and floodplains have not developed (deposition on interior bends forming new land).

Stage 2: As the stream begins to age floodplains begin to form, the valley widens, sand bars begin to form and the down cutting (deepening) of the stream lessens.

Stage 3: In the next stage the valley has widened, a narrow floodplain is evident and continues to develop and the river begins to meander.

Stage 4: In the final stage, overall relief of the area is generally flat, the river meanders significantly and oxbow lakes may have formed. The river straightens out, and the cycle begins again.

Using the information above go to N 42 46.108 W 073 50.007. At this location:

1. Measure the depth the stream has eroded down, take a measurement at the bottom of the hill (near the stream bed) and the top of the hill (trail-highest point) – email the difference. This may be done more easily by walking along the stream bed to the right point and then walking back along the bed to the trail and taking the trail back up to the top.
2. Email which stage of development you believe this portion of the stream is at and WHY.

Here is a picture from Oxbow, ND. I wonder why they named it Oxbow?

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• No Fault of Your Own
• Tory Rock Glacial Erratic
• Folding and Moving Time
• Henry G. Reist Wildlife Sanctuary
• Margaret Burke WMA Earthcache

I am a proud

Disclaimer: You, and all members of your party must read and agree to the www.geocaching.com disclaimer. In addition, you all must agree to hold the cache owner, www.geocaching.com, and the landowners harmless from any and all causes for action. You and all other members of your party must individually and collectively determine your/their physical fitness and outdoors/hiking skill levels, decide whether or not to visit the various cache locations, and whether or not it is safe and prudent to do so under the conditions that will be encountered. Cache seekers assume all risks involved in seeking these cache locations.

People that do not wish to do a cache because of any danger they might perceive to be present is certainly within their right to not proceed. However you do not have the right to try to ruin the enjoyment of others in attempting a find that is beyond your capabilities, but not beyond theirs. This goes for almost every caching event there is. After all one might run into spiders, snakes, poisonous plants, trips and falls and the list goes on.

Safety First! .......Take a friend, Look out for others, take a cell phone if possible, watch where you're stepping, NEVER UNCOVER ANY CACHE WITH YOUR HANDS OR FEET, USE A STICK! If you feel uncomfortable in doing a cache, for any reason, just walk away!!!