At the designated coordinates you will find a large quartzite rock with the evidence of the ancient Precambrian sea that covered this area millions of years ago.
The informational sign next to the rock states:
Imagine this area over two billion years ago, covered by the waters of an ancient Precambrian sea. This ocean deposited sand on the sea floor and these ripple marks on the rocks in front of you formed by wave action in the sand.
Over time, the sand grains cemented and transformed into sandstone, and eventually, with more heat and pressure, into quartzite, a very hard rock. This process preserved these ripple marks.
For the next several hundred million years, extensive weathering and erosion reduced the surrounding region to a flat "peneplain." However, Rib Mountain, with its hard, resistant quartzite, projected high above the surface.
Then, about 600 million years ago, expanding oceans covered Wisconsin, depositing thousands of feet of sediment. Slowly, these layers of sediment wore away, once again revealing Rib Mountain and its ancient ripple marks.
Ripples in sedimentary Rocks
Ripples form as wind or water pass over sand and pick up the grains and deposit them further along. As grains pile on top of each other, ridges form perpendicular to direction of the current.
Ripples can indicate the direction of a current because its steep side points in the direction of the flow. When the ripple are all generally parallel, they are termed to be asymmetrical in shape. These are usually formed when the current is traveling in the same general direction. Symmetrical ripples are formed as waves rock back and forth in shallow water and will look like someone tossed a box of toothpicks in the air and they all landed in multiple directions.
Your goal
You will travel to the site and gather information there to answer these three questions. Do not post your answer in your log, even if it is encrypted. Log your visit and then e-mail me your answers.
1) Approximately how far apart are the ripples? (If you are coming unprepared without measurement device, use one of your fingers to measure with and measure your finger later.)
2) On the informational sign is an artist's depiction of the Precambrian sea. In the drawing is a lifeform. What is it?
3) Are the ripples asymmetrical or symmetrical and, if asymmetrical which direction did the current flow? (i.e. left to right, top to bottom, bottom left to top right)
Access to the site
This Earthcache is located in the Rib Mountain State Park. The Entrance to the State Park is located at N 44 54.538 W 89 39.574. If you are into mountain climbing (it's only 800' from the bottom, you could walk up for free. To drive you will need to have or need to purchase a State Park Sticker. Prices vary depending on discounts on whether you are a Wisconsin resident, but it is basically a $7 per day fee. See the Rib Mountain State Park web site for more information.
For those who want to delve deeper into this subject here are a few web sites to check out:
The CSU Long Beach, Department of Geological Studies has an article on Environmental Clues in Sedimentary Rocks
The BIOONE Online Journals show the results of Threshold for Ripple Formation on Artificially Roughened Beds: Wave-Flume Experiments