Crooked River Sinkhole
Geocache Description
The Crooked River Preserve is a 60 acre preserve established to ensure the preservation of a mile of forested wetlands along the Crooked River corridor. The preserve is owned and managed by the Lake County Water Authority. Protection by the LCWA will ensure the environmental quality of Crooked River and the Preserve, as well as provide compatible recreational use for the residents of Lake County.
Park hours are sunrise to sunset. No Night Caching, Please!
The Sink Trail (blue trail) takes visitors to one of two sinkhole lakes on the property. Follow the Orange Trail to the Sinkhole Trail and observe the sinkhole from the two waypoints provided.
Along the trail you may spot local wildlife. I've seen gopher tortoises, sandhill cranes, lots of squirrels and the occasional cute little rat snake. Feel free to mention in your log any wildlife you see.
Sinkholes
A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. ... If there is not enough support for the land above the spaces, then a sudden collapse of the land surface can occur. Sinkholes are usually circular and vary in size both in diameter and depth. Sinkholes may form gradually or suddenly, and are found worldwide.
Karst Topography
Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves.
Sinkholes form when water washes sediment down into cracks and voids in karst bedrock.
Acidic groundwater moves through fractures and spaces within the rock, slowly dissolving and enlarging spaces to create larger openings and connected passages.
Type of Sinkholes
Solution sinkholes
Solution or dissolution sinkholes form where water dissolves limestone under a soil covering. Dissolution enlarges natural openings in the rock such as joints, fractures, and bedding planes. Soil settles down into the enlarged openings forming a small depression at the ground surface.
These sinkholes are the result of there not being much groundcover, like vegetation, over the bedrock. Water slips through pre-existing holes in the bedrock and begins to circulate through. A depression in the ground forms, and if the bedrock layers beneath are sturdy enough or there’s enough debris blocking the flow of water, the sinkhole may stop deepening. This could result in the formation of a pond-like areas and even wetlands.
Cover-subsidence sinkholes
Cover-subsidence sinkholes form where voids in the underlying limestone allow more settling of the soil to create larger surface depressions.
These sinkholes start with something permeable covering the sinkhole. Sediment begins to spill into empty caverns among the bedrock. Over time, a depression in the surface may occur. This sediment can block the caverns and prevent the flow of water. These sorts of sinkholes are never very large since the sediment prevents the water from further eroding the surrounding bedrock.
Cover-collapse sinkholes
Cover-collapse sinkholes or "dropouts" form where so much soil settles down into voids in the limestone that the ground surface collapses. The surface collapses may occur abruptly and cause catastrophic damages. New sinkhole collapses can also form when human activity changes the natural water-drainage patterns in karst areas.
Cover-collapse sinkholes are the most dramatic. The surface area above the bedrock in this instance is mostly clay. But since the clay is sturdy, arches form as its slowly spalls. This arch continues to support the surface ground until it becomes so thin that it collapses into the cavern below, swallowing up everything above it.
Lakes
A lake is an area filled with water, localized in a basin, surrounded by land, and set apart from any river or other outlet. Lakes are typically larger and deeper than ponds, which also lie on land, though there are no official or scientific definitions. Most lakes are fed and drained by rivers and streams.
Information gathered from LCWA, Wikipedia and US Geological Survey
Logging Requirements:
Please email or message the answers to the following questions.
- Observe the sinkhole from one of the two posted coordinates. Based on your observations and the information provided, what type of sinkhole is this?
- From the shape of the pond, you can easily tell this is a sinkhole and not a lake. How?