Maumee River Alvar EarthCache

This Earthcache will be a nice visit to what, globally, is rarely found. We are fortunate in the great lakes region to have about 120 alvars. Now that may sound like a lot but realize that encompasses all the great lakes and many of these alvars are in Canada. Another thing to remember as you visit this alvar, many of the 120 or so alvars are covered with vegetation and are not visible for this reason. The Maumee River Alvar is very exposed which makes it a fantastic example. The other nice thing about this particular area is that it is a very large section of exposed alvar.

What is an alvar and how did it come to be?
Alvars can take on several forms but is always comprised of sedimentary rock. The sedimentary rock here is dolomite, we know it as limestone. This dolomite dates back some 350 million years and contains sea fossils. The earth’s sea covered this area and with the hot earths crust changing, minerals were settling in the seas. Limestone consists largely of the mineral calcite (calcium carbonate) it also contains varying amounts of silica, clay, sand and silt. Alvars can be broken fragments of limestone; this kind makes up many of the areas of the Maumee River banks. They can also be large block-like chunks of limestone with deep grooves, making them look like they are separated. Then you have alvars like you have here: large slabs of limestone that look like pavement. The different types of alvars are, for the most part, in their form because of glaciers. As the ice sheets of the glaciers retreated, this area was scraped which gave this alvar a “pavement” look. The rise and fall of the Maumee River also helps smooth the rock.

Many alvars have fallen victim to human destruction. Many alvars have been mined out for the limestone while others have just been built over. This alvar is fortunate to be protected by the park system's ownership. With so much urban sprawl in this area this is a great find and a great place to visit. When you are here for a visit please remember there is a lot of loose rock in the area. Be careful where and how you approach this alvar. Please keep in mind at any alvar that many plants in the area are found only in the areas of an alvar; be sure to use paths of exposed rocks.

Part of your visit is to discover other aspects of this alvar. So to get credit for this cache you will be required to complete the following tasks. Photos other than signs should be posted with your log entry. All answers to the following questions will have to be e-mailed to me and not written in your log.

1. Go to the posted co-ords. At this point there are 2 very clear and interesting aspects to this alvar. One is right at your feet the other is the look of the alvar as you look towards the bank. E-mail me a detailed explanation of these features.
2. Take a photo of yourself at the alvar with the Maumee River in the background. Post this picture with your log.
3. As you leave the alvar you will find a sign directly at the road from the alvar. That sign describes what the alvar is doing to the river. Include in your e-mail what the alvar is responsible for.

This cache is placed with the permission of the Metroparks Toledo Area.