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Often we only see solutional sinkholes when they do damage such as apparently eating a swimming pool, some roadway, and buildings. But this earthcache will help you better understand, not only, how they are formed but why they are important.
This area of New Brunswick has bedrock that is a high quality gypsum/limestone and has allowed the formation of this post-glacial sinkhole. Solutional sinkhole that is known regionally as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the surface topography caused by the removal of soil or bedrock, often both, by water. Sinkholes may vary in size from less than a meter to several hundred meters both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. They may be formed gradually or suddenly, and are found worldwide.
The mechanisms of formation in this area is the gradual removal of slightly soluble bedrock by percolating water, the collapse of a cave roof, or a lowering of the water table. On the surface, sinkholes may develop progressively as subtle, bowl-shaped depressions, or collapse suddenly into steeply sided, water-filled craters. The shape of the sinkhole, and the speed that it forms, depend on the size of the subsurface cavity and the thickness of the overburden (sediments or organic matter that rest on the bedrock). If the overburden is thin or absent, often the case in this area, the surface of the bedrock is broken down by erosion from surface water. This wilderness bowl-shaped depression formed naturally slowly and continuously as chemical and physical processes erode the rock.
Sinkholes originate beneath the surface when groundwater moves through the bedrock and erodes large voids, or cavities. When water fills a cavity, it supports the walls and ceiling, but then the water-table dropped, the cavity was exposed to further erosional processes from the surface that eventually result in the collapse of the cavity, causing a surface indenture, or sinkhole. The sinkhole becomes a primary site of recharge, where surface water can enter the aquifer and replenish the groundwater supply. Sinkholes have been used for centuries as disposal sites for various forms of waste. These sinkholes were formed by groundwater therefore are a direct connection to the water table below. A consequence of materials entering these sinkhole with the water becomes the pollution of groundwater resources, with serious health implications in such areas.
At the posted coordinates you will find yourself at the end of a long line of sinkhole starting about 2 miles to west, you can follow the line to the west visiting several other sinks. To log this Earthcache: You must visit the area and answer an earth science question. There is no container or logbook for you to sign just a unique natural feature to observe. As you look at the sinkhole think about what it must have been like to be in this location when the collapse took place. Using my profile email me the size of the sinkhole (length, width and depth) and what you think the sinkhole has been used for in the past. Please include the name of the earthcache and the number of people in your group in your email. In your log please take the time to describe what you find special about this beautiful wilderness forest location. You may also want to include a photo so others have something to look forward to when they visit..
Imagine if you will on Feb. 23, 2007 a 100 meter deep sinkhole formed in Guatemala City, Guatemale killing two people as it swallowed about a dozen homes in the early morning. On May 9, 1981, a large sinkhole collapsed in Winter Park, Florida, swallowing a house, five Porsches at a luxury car dealership, and half of an Olympic-sized swimming pool. In Cape Breton, Nova Scotia a team of horses fell into a sinkhole as it collapsed, while it did not kill the animals it did cause an issue when they had to be removed.
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