A limestone pavement is a natural karst landform consisting of a flat surface of exposed limestone that resembles an artificial pavement.
Conditions for limestone pavements are created when a glacier scrapes and exposes the limestone as it advances and recedes, leaving behind a flat, bare surface. Limestone is slightly soluble in water and soluble in acid, so corrosive drainage along joints and cracks in the rock can produce blocks called clints and deep cracks called grikes. If the grikes are fairly straight and the clints are uniform in size, the landscape looks like it is made of artificial paving stones. Limestone pavements can have more rounded forms as they are eroded over time.
Alvars are globally rare, naturally open habitats with either a thin covering of soil or no soil over a base of carbonate rock, such as limestone or dolostone. The presence of alvars is one reason why Manitoulin is unique. Most of these features on the island likely formed in the last 15,000 years following the last ice age.
An alvar habitat has formed at this location. Juniper bushes, grasses, and sedges are typical of the alvar plant community. There are several classifications of alvar types such as:
- Shoreline alvar: bare limestone and dolomite along the lake shore;
- Open alvar pavement; (Flowering Plants of open alvar pavement, inland from shore alvar);
- Open alvar grassland; <25%tree and shrub cover and >50% herbaceous cover with grasses and grasslike plants;
- Alvar Woodland >25%, but <60% trees;
In order to log this EarthCache as found you have to answer following questions:
- What kind of bedrock is in this area?
- What type of Alvar can you see at this location?
- Measure the size of the deepest grike in this area. How deep, wide, and long is it?
- Do you think it will keep getting bigger in the future?
- Post a picture of yourself with your GPS unit at the posted coordinates with the Alvar landscape at the background. (optional)