This is not your usual type of geocache. For one thing, there is no physical geocache for you to find. Rather, this is a special type of virtual cache known as an EarthCache.

An EarthCache teaches an earth science lesson. The cache page must include logging tasks that help teach the same lesson. Geocachers must complete the tasks before they log the EarthCache as found.

For more information on EarthCaches, see the Geological Society of America's website.

Finding this Earthcache:

In order to get credit for finding the cache, it is not enough to log it below. You also must complete the following seven tasks. Include the first four tasks (photos, date, description, and distance/number of steps) in your log. For the remaining three tasks, send the answers to the Cache Owner in a message or EMAIL. DO NOT place your answers to tasks 5-7 in your log entry!!!

NOTE: The logging tasks require a bit more thought and effort than many Earthcaches, thus justifying the higher D rating. However, perfection is not required. A good faith attempt to fulfill the logging requirements should be sufficient.

Tasks to be Completed and Reported in Your Online Log:

1. The given coordinates take you to the Travel Wisconsin Selfie sign at Peck's Landing. To prove that you were at the Earthcache site, take a selfie of you or a personal item at or using the selfie sign and showing the sandbar (if any). Post that photo with your log.

2. Include the date and time of your visit in your online log.

3. Follow the trail east along the river to the second waypoint (N43 08.796 W90 03.564). There should be a short connector trail from the main trail along the river bank down to the sandbar/river. From that point, look at the opposite side of the river for the break in the trees and number of large white rocks (used for erosion control). If there is an emergent sandbar accessible from the riverbank, walk across it toward those rocks, either counting the number of steps or recording the distance from WP2 until the point where your feet would get wet if you continued walking (you can estimate the last few feet). Record that distance (in steps, feet, or meters). Include that distance and a description of the sandbar (and any additional sandbar(s)) between WP2 and the rocks in your online log. Of course, if the river is high and there is no visible sandbar, or you are unable to get to WP2 due to flooding, simply note that fact in your online log.

4. Include a photo in your online log taken from WP2 and with the white rocks in the background, showing the appearance of the river and any sand bar(s) as they exist on the date and time of your visit.

Email or Message the Answers to the Following Tasks to the CO:

Note:  Do NOT include this information in your online log.

5. Identify any differences in the appearance of the sand bar between that as reported and photographed by the previous finder and that observed by you. What do you think caused any such changes and why do you think so?

6. Based on the information below and your observations, what type(s) of sand bar(s) were present at WP2 at the time of your visit?

7. At the time of your visit, did you see any sand bar(s) on the opposite (South) side of the river? Would you expect to see any there? Why or why not?

Sandbars

Rivers change over time, and the Lower Wisconsin River is no exception. Wisconsin River water flow can change from season to season and even from day to day. See Lower Wisconsin State Riverway Conditions.  The river channel is also constantly evolving, eroding sediment from one bank only to deposit it elsewhere to form a sandbar or an island.  This Earthcache addresses how sandbars like the one usually visible at GZ are created in rivers like the Wisconsin River.

What is a Bar?

A bar in a river is an elevated region of sediment (such as sand or gravel) that has been deposited by the flow. A sandbar is a deposit of sand along the bank of a river or in other areas where the river current slows down.

Erosion and Transportation

River bars are composed of Sediment, solid material that is moved and deposited in a new location. Sediment can consist of rocks and minerals, as well as the remains of plants and animals. It can be as small as a piece of dust or a grain of sand or as large as a boulder.

Rivers generally carry with them a steady quantity of sediment. Sediment moves from one place to another through the process of erosion. Erosion is the removal and transportation of rock or soil. Erosion can move sediment through water, ice, or wind. In a river or stream, sediment can be eroded from either the banks of the waterway or from its bed.

The amount of sediment carried by a particular river or stream turns on a number of factors, including the depth of the waterway and, most importantly here, the speed of the flow. The faster the water in a river channel, the better it is able to pick up greater amounts of sediment and larger pieces of sediment.

As shown in this diagram from the Geological Society of London, flowing water transports different types of sediment in different ways.

• Traction is the rolling or dragging of large grains along a river bed or shore, aided by the push of the smaller grains (below).
• Saltation is the bouncing of sand grains as they are picked up, carried along, and dropped repeatedly by flowing water. 
• Fine particles (silt and clay) are carried in Suspension in the water – they will only settle out if the water is still.
• Soluble salts are carried in Solution in the water – the sea is obviously salty, but rivers contain dissolved salts, too.

Deposition and Creation of River Bars

Deposition takes place when the water flow slows down and no longer has sufficient energy to transport all of the sediment it is carrying. As a result, some of the sediment settles to the bed of the stream or river. Larger, heavier particles like pebbles and sand are deposited first, while the lighter silt and clay only settle if the water is almost still.

The flow and depth of water at a particular location in a river is constantly changing based on the amount of water entering it through rainfall, snow melt, and the like, and water leaving it through evaporation or simply flowing downstream. If more water enters a portion of the river than leaves it or moves on, the water level rises. If the water leaving a location in the river is not fully replaced by new inflows, the water level falls. When the flow of water at a given location is reduced to the point that the deposited sediment is no longer under water, it is called an Emergent Bar.

Erosion and Deposition in Meandering Rivers

A Meandering River has a single channel that winds snakelike through its valley, so that the distance 'as the stream flows' is greater than 'as the crow flies.' As water flows around these curves, the outer edge of water is moving faster than the inner. This creates an erosional surface on the outer edge (a cut bank) and a depostional surface on the inner edge (a point bar).

Meanders change position by eroding sideways and slightly downstream. The sideways movement occurs because the maximum velocity of the stream shifts toward the outside of the bend, causing erosion of the outer bank. At the same time the reduced current at the inside of the meander results in the deposition of coarse sediment, especially sand. Thus by eroding its outer bank and depositing material along its inner bank, a stream moves sideways without changing its channel size.

Source: National Park Service https://www.nps.gov/articles/meandering-stream.htm

Types of River Sandbars

A Point Bar is a crescent shaped area of deposition typically found parallel to the bank on the inside curve of bends in meandering rivers.  As the flow moves around the inside of the bend in the river, the water slows down because of the shallow flow and low shear stresses there reduce the amount of material that can be carried there. The excess material falls out of transport and, over time, forms a point bar.

While a point bar generally abuts the riverbank, a Mid-channel Bar is, as suggested by its name, located away from the bank.  One type of mid-channel bar is a Braid Bar, so called because they are often found in braided river channels. Braided river channels are broad and shallow and found in areas where sediment is easily eroded like at a glacial outwash or at a mountain front with high sediment loads.

Bars can also form mid-channel due to snags or logjams. For example, if a stable log is deposited mid-channel in a stream, this obstructs the flow and creates local flow convergence and divergence. This causes erosion on the upstream side of the obstruction and deposition on the downstream side. The deposition that occurs on the downstream side can create a central bar, and an arcuate bar can be formed as flow diverges upstream of the obstruction. Continuous deposition downstream can build up the central bar to form an island.

A Mouth Bar is an elevated region of sediment typically found at a river delta which is located at the mouth of a river where the river flows out to a lake or the ocean. Sediment is transported by the river and deposited, mid channel, at the mouth of the river. This occurs because, as the river widens at the mouth, the flow slows, and sediment settles out and is deposited

SAFETY

The following information is provided by the Wisconsin Department of Natural Resources.

The Lower Wisconsin River may look lazy and slow, but the many inviting sandbars can be a trap to the visitor who is not aware of the power hidden from view.

Even at its normal flow, the current is strong enough to sweep a grown adult off their feet, and in only a short time the flow can increase to a strength that can overturn a full-sized car. This flow is often not even noticeable to the person standing on the bank or wading in the shallow water at the edge of a sandbar, but is strong enough that even a strong swimmer may not be able to swim against it.

Even more dangerous is the effect this current has on the sandy bottom of the river. Sandbars are constantly moving, and the downstream end is often unstable and will not support a person walking on it. Sometimes, the sand is even undercut and an unsuspecting person can step from a few inches of water into a deep hole.

Many people have tragically drowned in the waters of the Wisconsin River because they did not understand or did not respect its power. A few simple things can keep you and your family and friends safe when using the river.

Dropoffs — The water depth on the downstream side of a sandbar can drop from a few inches to many feet with one step. Water erosion can cause the unexpected collapse of sandbars and shorelines. If you wade in the river, wade in pairs and walk on the upstream end of the sandbars.

Current — Avoid flow through hazardous such as tree branches overhanging the shoreline. Even in slow water, these can sweep you out of your boat or capsize your craft. Do not swim against the current. Float downstream to an area where you can safely get out of the water.

Drownings — Wear a personal flotation device (PFD). Personal flotation devices will keep you on top of the water if you do step into a deep hole. The DNR encourages everyone to always wear a life preserver when in or on the river.

If you are not prepared to swim it, do not canoe or wade it!

Signs have been placed at each point of public access along the Lower Wisconsin State Riverway warning visitors of the current and the drop-offs. Please heed the warnings and be careful when using the river.

Permission

The Geocache Notification Form has been submitted to, and permission granted for this placement by, Jesse Kellogg of the Wisconsin Department of Natural Resources. Geocaches placed on Wisconsin Department of Natural Resource managed lands require permission by means of a notification form. Please print out a paper copy of the notification form, fill in all required information, then submit it to the land manager. The DNR Notification form and land manager information can be obtained at: dnr.wi.gov/files/PDF/forms/2500/2500-118.pdf (visit link)