The Grand Tour - The Ledge
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This is a 1 stop Earthcache.
The other stops "DO NOT" have to be visited. They are only posted for you to visit and enjoy if you so wish. I highly recommend making the "other" stops part of your tour.
At each of the two (2) entry points listed (#1 - N44 38.219 W87 48.099 and #2 - N44 38.241 W87 47.918) are stairways with handrails bringing you down to a Cliffside walkway. Follow this walkway from one entry point to the other. Along this walk you will encounter a small cave, joints, a large erratic (Gneiss?) nestled within one of the joints (very near the coordinates), scree/talus, cherty layers, vugs and so much more. See if you can locate all of these things as you travel along the walkway.
Once at the coordinates, look for 2 large sections of Limestone that have broken away from the Escarpment, slid downhill and tilted. Once located, you will have to use your GPS or compass to get the answer to #4.
1. List 2 factors you believe helped in these 2 sections breaking away from the Cuesta.
2. What is the process of downhill slippage of large rock sections called? (found somewhere within the write-up)
Proof of visitation:
3. The smaller section has tilted more than the larger section. As you face these sections, which side of the smallest section is lower? The right side, or the left side?
Email your answers to the questions, to me, using the link in my profile only. If your answers are not recieved by me, your log will be deleted. Photos are accepted and appreciated as long as the answers are not pictured. You do not have to wait for confirmation from me before logging this cache as completed. Most of all……learn……and enjoy the view.
Other interesting sites
Red Banks Alvar
An Alvar is a horizontal exposure of Limestone or Dolomite bedrock, with a thin, to nonexistent soil layer. As a result of this thin soil layer, vegetation is sparse, with trees and bushes being absent or at least undersized. In many aspects, this landscape resembles a dry oak Savanna. This Alvar, a former lake bottom, was exposed by glacial erosion over 10,000 years ago. It is kept open by a variety of environmental factors including wind, rain, fire, and water runoff. Alvar communities are extremely rare worldwide and even rarer within Wisconsin, with more extensive Alvars located in New York, Michigan, and Ontario, Canada. Within the entire Great Lakes area, there are only about 120 Alvars, which compromise only 0.2% of the total land area.
Only a few specially adapted plant species have the ability to survive on such a hostile terrain as this. White cedar trees, some found to be 1800 years old, still grow here. Plants occupying this area include northern Bog Violet, Balsam Squaw-Weed, Cream Gentian, Juniper Sedge, Crawe’s Sedge, Kalm's Lobelia, Pringle's Aster and Lakeside Daisy. A diverse collection of Lichen, Algae and Mosses can also be found thriving here. This area provides habitat for a variety of bird species such as Bobolinks, Loggerhead Shrikes, Upland Sandpipers, Eastern Towhees, Brown Thrashers, Eastern Meadowlarks and at least 20 different species of butterfly. The Red Banks Alvar lies on the top of, and near, the edge of the Niagara Escarpment.
The Niagara Escarpment
The bedrock of the Red Banks Alvar is composed of 400 million year old Dolomitic Limestone. This bedrock is part of a 650-mile long, arc shaped ridge, called the Niagara Escarpment. Also called a Cuesta, this ridge rises 200 feet above the Lake Michigan water levels that we see today. This ridge formed from the effects of erosion and not from any faultline or tectonic disturbance. The locals lovingly refer to this ridge as "The Ledge".
These Dolomitic cliffs provide habitat to a varied collection of rare plant and animal species. One of the most diverse snail communities ever found in the Midwest, thrives in this area. At least nine snail species, all thought to have gone extinct at the end of the last Ice Age, have been found living on these cliffs and rocky slopes. Plant life, including the Canadian Yew Shrub, Walking Fern, Leaf Cup, and rare Rock Cress, grow above, on, and below this Cuesta. This area is also the home of the second oldest native forest found in North America.
Karst Topography
Rain, on its journey to becoming groundwater, passes through the atmosphere and picks up CO2. CO2 dissolves in water forming a weak carbonic acid solution. When groundwater flows through the fissures and bedding planes of limestone, a process called dissolution (dissolving) occurs. Limestone, having high calcium carbonate content, dissolves easily in these acids forming what is called Karst topography. This acid eaten topography can include impressive caves, labyrinths, passages, aquifers and sinkholes (dolines). Groundwater seepage through the fissures and bedding planes can be seen on the vertical faces of this porous landscape.
Because of its sedimentary nature, the Dolomitic Limestone rock layers (bedding planes) of the Niagara Escarpment fracture horizontally and vertically, creating fissures and crevasses called Joints. These Joints fill with topsoil, collect moisture, and support conditions for better plant growth. These joints appear through the thin soil layer as lines of, often taller, larger and healthier plant life.
Beneath the buff colored Limestone layers of the Cuesta lies a soft impermeable layer of blue-gray colored Shale. Approximately 500 million years ago, particles from the erosion of the Appalachian Mountains were transported westward by winds and water currents and deposited in a shallow intercontinental sea. The process of Lithification alters these erosional deposits, changing them into Maquoketa Shale. The exposures of Shale located at this site are the oldest rock exposures found Northeast of Green Bay.
Shale, being softer than the overlying Limestone, erodes quicker than the limestone once exposed. Erosion of this softer Stratum creates unsupported outcroppings in the overlying Limestone. Gravity, along with plant root growth and ice wedging, aid in the expansion of joints causing large blocks of the Limestone bedrock to break away from the face of the Escarpment.
A Glacial Erratic is a rock usually referred to simply as a field stone, a boulder, intercoursite or a leaverite (as in "leave-er-right" there) by the layman. These leave-er-rights are caused primarily by the processes of abrasion and plucking. Plucking occurs when sub-glacial waters penetrate fractures in bedrock, freeze and expand, causing large sections to break away. A process called ice wedging. The abrasion process occurs when a glacier surges forward and entrapped rocks within, act like sandpaper eroding the bedrock below. Both of these processes lift and separate various sized rocks, entrap them and carry them along with the advancing glacial ice. Scars, carved in the bedrock by this moving rock flow, are called glacial striations and are used by researchers in mapping the path of glacial movement. When the glacial ice melts and retreats, the rocks entrapped within are stranded in a landscape foreign to their parent bedrock. Geologists define this orphaned rock as a Glacial Erratic.
Bringing It All Together
The most recent advance of the Laurentide Ice Sheet to cover parts of the upper Midwest was called the Wisconsin Glacial Episode. It began some 30,000 years ago, reached its greatest advance 18,000 years ago and ended around 10,000 years ago. This Wisconsin Glaciation advanced in six separate and distinct lobes (fingers of ice) covering most of the state. Of importance in Northeast Wisconsin are the Lake Michigan Lobe and the Green Bay Lobe. The Lake Michigan Lobe advanced down the Lake Michigan lowlands reaching as far south as central Indiana and Illinois. The Green Bay Lobe advanced down the Bay of Green Bay lowlands reaching the Baraboo Hills and Janesville areas. The separation of these lobes was caused by the highly resistant Dolomite caprock of the Niagara Escarpment. The Green Bay Lobe was perhaps several hundred feet high at its edges, thousands of feet thick at its center and littered with rock debris. Advancement and subsequent retreat of the Wisconsin Glacial Episode drastically altered the topography of Wisconsin. Kettles, Moraines, Drumlins, Eskers, Erratics and Glacial Striations (etc.) are all evidence of its awesome power. All of the geologic formations listed above were acted upon or affected in one way or another by the Green Bay lobe of the Wisconsin Glacial Episode.
Only the coordinates listed at the top of the cache page must be visited to complete this EarthCache. The other coordinates will take you to other sites and geologic wonders in the area that I find interesting. If you decide to visit all of the sites listed, it is less than a 7 mile drive from start to finish.
At the Red Banks Alvar coordinates, look to the North of the road. Here you will see White Cedar trees estimated to be 1200 to 1800 years old. This can be done without leaving your car. Millions of people have passed this way not knowing that they are in the middle of an Alvar, much less knowing what an Alvar actually is. N44° 36.875 W87° 49.765
At the Limestone Joint coordinates, face East and scan the open field for lines of taller vegetation. You will not have to leave your car to observe this either. At various times throughout the entire year, I have been able to distinguish these lines, and at other times, sad to say, I was not. I hope you are lucky enough to observe these wonders. N44° 38.038 W 87° 48.260
At the Niagara Escarpment coordinates a house sized mass of Limestone (slumpblock) has broken from the Cuesta and moved. This process of movement is called Slumping. The large mass seen here has remained intact because of "slow" downslope movement, unlike that of a landslide, which occurs much more quickly. This slow movement allows for most shear scars to erode and weather away before the block finally comes to rest. This slumpblock can also be seen without leaving your car. Another nice little roadside wonder I find interesting. N44° 36.671 W87° 50.758
At the Maquoketa Shale coordinates you will have the pleasure of observing a waterfall in addition to the Maquoketa Shale layers. This can be done without leaving your car also, but to get a full view of the falls and Shale, visit the observation deck located there. The Shale layers, being a different color than the overlying Limestone, will be easy to pick out. This is one of the few sites Northeast of Green Bay that these Shale layers can be observed. N44° 34.119 W87° 52.767
The Geocache Notification Form has been submitted to Doug Hartman, Brown County Facility and Park Management Department of the Wisconsin DNR. 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 and then submit it to the land manager. The DNR Notification form and land manager information can be obtained at: http://www.wi-geocaching.com/modules.php?name=Wiki&pagename=Hiding%20A%20Cache
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