Sand, Beach, Dunes And LSD EarthCache
Sand, Beach, Dunes And LSD
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Composition
The most common type of shoreline in the Great Lakes area is the sand beach. Sand consists of rocks, crystals, shells, and the skeletal remains of organisms, eroded over time by wind, water, and ice. Sand composition can differ greatly from one area of the world to another. In the south Pacific, black sand beaches are composed mainly of volcanic ash, while the white sands of New Mexico are composed mainly of gypsum. Beaches around the Great Lakes area are composed of sediments from erosion of Limestone (Calcium Carbonate), Sandstone (Quartz/Feldspar) and Granite (Quartz/Feldspar). The mineral Quartz, being abundant, chemically resistant and durable, is the major ingredient of beach sand. Generally speaking, beach sand found around the Great Lakes is buff in color and will contain small particles of Magnetite. Magnetite is also chemically resistant, durable and resists abrasion. This makes Magnetite normally the major non Quartz mineral found in beach sand.
Ancient Beaches
Common in certain regions of the Great Lakes area are formations called beach ridges. These ancient ridges were once the sandy shores of Lake Michigan. 3,000 to 4,000 years ago, water levels in Lake Michigan were almost 40 feet higher and extended a mile farther inland than what we see today. As the water receded, these ridges remained, marking the ancient shorelines of the lake at that time. Each of these ridges took an average of 30 to 50 years to form. The Ridges Sanctuary in Baileys Harbor contains 30 such beach ridge formations. Point Beach Ridges, located within Point Beach State Forest in Manitowoc contains 11 of these ancient ridges. More can also be seen in Whitefish Dunes State Park just south of Jacksonport.
Formation
Creation of sand beaches is due in the most part to wave action. Waves, washing onshore are called Swash, and move in the same direction as the prevailing winds. These waves collect sand from the bottom, wash in, and deposit some of these particles on the beach before retreating. The retreating (offshore) backwash, due to gravity, always flow perpendicular to the shoreline. As this backwash loses energy, it drops more of these sand particles during its retreat. The next wave again picks up these particles and moves them slightly further down the beach. This zigzagging of wave action causes a continual lateral movement of sand along the shoreline in one direction. This process of sand movement is called long shore drift (LSD) and can be observed on all beaches. LSD is the reason for long strips of coastline to be covered in sand, not just the areas around river mouths, which are the main source of beach sand.
The wind is yet another aid in the creation of beaches. As wind hits the shoreline, it picks up grains of sand and carries them inland, widening and lengthening the beach. Pioneer Beach grasses, such as marram grass, wheat grass and sand reed grass, slow the winds, forcing them to drop their load of sand. This accumulation of windblown sand marks the beginning of sand dunes.
These dune grasses also act as stabilizers, enabling the root systems of shrubs to establish and strengthen the dunes. Eventually trees such as juniper, northern red oak, eastern white pine, and paper birch take over. For a dune to evolve into a full grown forest, it will take approximately one thousand years.
Importance
Beaches and dunes are home to many animal and plant species. Houghton's Goldenrod, pitcher's thistle, American Bugseed, Crinkled Hair Grass, and Dwarf Lake Iris are all examples of plant species found in these areas. Algae, Beetles, Spiders, and other micro fauna living in driftwood and debris make for a rich feeding ground for many migratory birds. Shorebirds such as Sanderlings, Golden Plovers, Sandpipers, and Ruddy Turnstones use the grasses, shrubs, and trees near the dunes as a nesting habitat. This area then attracts other mammals such as Fox, Deer, Squirrels, Rabbits, raccoons, and more.
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.
1. Using you best guess, what is the direction and speed of the long shore drift at this location?
2. Using you best guess, what is the speed and direction of the wind at this location?
3. Put a few grains of sand in your hand and add a few drops of Vinegar. Does any bubbling occur and if so, how much? This will show proof of a calcium rich (bubbling occurs) or a calcium deficient (bubbling does not occur) beach sand.
4. Drop a magnet into an area of “dry” sand and then remove it. Tell me what you see and what you think could be the cause?
5. Were sand dunes being formed or destroyed at the time of your visit? Explain how you came about this answer.
Go to the link below and click “stop animation”. Click on “time and date”. Set it to the time and date that you visited the location. Use the area just north of Kewaunee to find the “actual” direction and speed of the water currents.
Water .
6. Were your estimates close to the actual measurements listed?
Go to the link below for “actual” wind speed/direction readings and a webcam view of Cresent Beach.
Wind.
7. Were your estimates close to the actual measurements listed?
The listed coordinates will bring you to the Algoma Visitor Center located on Crescent Beach. Here you will find a wheelchair accessible, half mile long, lighted Boardwalk with plaques providing information on the history of the lakefront and vegetation growing nearby. Take a stroll on the beach or continue following the boardwalk and visit the Algoma Marina, a century old red lighthouse, a memorial to a fallen police officer and Christmas Tree Ship Point (another memorial). Along the way are stationed benches, picnic tables and a park with a playground.
At times you will have to go back and reclick on the water current direction and speed link to get it to work for some unknown reason.
Permission granted by Terry Qualman Parks & Recreation Director for the placement of this EarthCache.
Additional Hints
(No hints available.)