Rock Across the River EarthCache

At the posted coordinates you will see an outcropping of Niagara Limestone that leads into and across the river.

People have been using the outcropping for 100's of years as a means to get across the river from the Indians that used to inhabit the area up through when the white men displaced them.

Now it will be your chance. :)

Please take some time and look at the rocks that make up this outcropping.

1) Take a look at the micro scale (get up close and personal) and in your email tell me what you see and what you think the rocks might be made of.

2) Look at the rock as a whole. In your email explain why it might of become separated from it's brothers.

3) Step back and look at the outcropping as a whole. In your email tell me how this spot made the river crossing easier and why you think it has lasted this long.

4) Now this is the fun part. :) Stride out into the river on the outcropping and measure the depth of the river as it flows over. Be very careful as the rocks might be slippery and do not attempt this after a heavy rain and if the water flow is too strong.

Please check the water levels at this site

5) This will be fun also! :) Get a picture of you standing on the ford in the river and post it along with your log. (optional)

6) Either continue crossing the river (be careful as it might be deeper towards the other side) or use the bridge just to the north and determine how wide the river is.

Some information for your educational pleasure... :)

Stony Ford

Stony Ford was the oldest Indian Ford in the Chicago Portage region and used by the red men as their principal crossing place from their villages on the Illinois River to the main portion of the Green Bay Trail along the shore of Lake Michigan. Stony Ford is located three-eights of a mile north of Laughton's Ford and one-hundred-fifty feet south of State Highway Number Four or Joliet Road Bridge. Stony Ford is presently marked by a wooden plaque on the east side of the parking lot in Stony Ford Woods. Stony Ford Woods is located directly west of the south side of 66 where the bridge ramp ends. The plaque faces the ford from the west side of the river and reads ---

Once across the Des Plaines the easterly branch of the Green Bay Trail continues southwest for three-fourths of a mile and ends a little ways east of Joliet Road at Forty-Seventh Street where it connects with Portage Road to form the Ottawa Trail.

The Niagara Escarpment

Put simply The Niagara Escarpment is the edge of a large bowl formed by and ancient lake that now contains Lakes Michigan, Huron and Erie. The edge of this bowl is quite prominent in Wisconsin, New York State and Ontario. While mostly covered with glacial till, outcroppings can be seen also in Michigan, Illinois and New York.

The Niagara Escarpment (in red) is a long escarpment, or cuesta, in the United States and Canada that runs westward from New York State, through Ontario, Michigan, Wisconsin and Illinois. It is composed of the Lockport geological formation of Silurian age, and is similar to the Onondaga geological formation, which runs parallel to it and just to the south, through the western portion of New York and southern Ontario. The escarpment is most famous as the cliff over which the Niagara River plunges to form Niagara Falls, for which it is named.

The Niagara Escarpment is the most prominent of several escarpments formed in the bedrock of the Great Lakes. It is traceable from its easternmost point in New York State, starting well east of the Genesee River Valley near Rochester, creating one small and two large waterfalls on the Genesee River in that city, thence running westward to the Niagara River forming a deep gorge north of Niagara Falls, which itself cascades over the escarpment. In Southern Ontario it stretches along the Niagara Peninsula hugging close to the Lake Ontario shore near the cities of St. Catharines, Hamilton and Milton where it takes a sharp turn north in the town of Dundas toward Georgian Bay. It then follows the Georgian Bay shore northwestwards to form the spine of the Bruce Peninsula, Manitoulin, St. Joseph Island and other islands located in northern Lake Huron where it turns westwards into the Upper Peninsula of northern Michigan, south of Sault Ste. Marie. It then extends southwards into Wisconsin following the Door Peninsula and then more inland from the western coast of Lake Michigan nd Milwaukee ending northwest of Chicago near the Wisconsin-Illinois border.

Dolomite (Niagara) Limestone

Dolomite is the name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate CaMg(CO3)2 found in crystals.

Dolomite rock (also dolostone) is composed predominantly of the mineral dolomite. Limestone that is partially replaced by dolomite is referred to as dolomitic limestone, or in old U.S. geologic literature as magnesian limestone. Dolomite was first described in 1791 as the rock by the French naturalist and geologist, Déodat Gratet de Dolomieu (1750–1801) for exposures in the Dolomite Alps of northern Italy.