CAVE POINT COUNTY PARK

This site offers a spectacular view of Lake Michigan and the eastern shore of the Door Peninsula.  Here the water currents on Lake Michigan have carved out caves in the dolomite rocks that form the Peninsula. 

Estimates of the extent of karst features are that they occupy approximately 10% of the landscape, and the aquifers found in karst terrains supply 25% of the population with water (U.S. Global Change Research Information Office website, 2002).  Karst is a limestone terrain where surface drainage is limited and soil cover is thin (Summerfield, 1991).  Karst has well developed underground drainage systems that result in landforms like sinkholes, disappearing streams, caves, and springs (U.S.Global Change Research Information Office website, 2002).  Karst features are associated with the solubility of limestone. Processes like dissolution and precipitation, sedimentation and subsidence, contribute to the development of karst terrains (U.S. Global Change Research Information website, 2002).  Karst topography is a product of weathering associated with groundwater flow and precipitation.  Karst regions are best developed in limestone, dolomite, and other carbonate rocks as well as evaporites such as gypsum and anhydrite.  Fractures along bedding planes contribute to the development of enlarged spaces that can become cavities beneath the surface (U.S. Global Change Research Information Office website, 2002).  These well-developed groundwater flow systems lead to pollution issues discussed on the Ellison Bay page.

Dolomite rocks, such at those that compose the Door Peninsula, are best formed in warm, moist climates where chemical weathering processes are very active (U.S. Global Change Research Office website, 2002).  When water reacts with CO₂ (carbon dioxide) in the atmosphere, a weak acid, called carbonic acid, is produced.  This weak acid is what is commonly known as “acid rain.”  Carbonic acid then reacts with the calcite (calcium carbonate) in dolomite rocks, resulting in slow dissolution of the dolomite.  Thus, acid rain is a primary factor in the development of karst features in dolomite (Western Kentucky University website, 2002).  Other problems associated with regions characterized by karst development include bedrock collapse and groundwater pollution.  Such situations can lead to extensive damage to roads, the necessity for expensive water treatment, and soil instability (U.S. Global Change Research Information Office website, 2002).  Because karst features are protected from surface weathering, environmental changes tend to be preserved within them, making them truly unique features (U.S. Global Change Research Information Office website, 2002).  Karst features respond to small changes in climate so they provide good data for temperature, and rainfall, vegetation, and groundwater flow patterns where they are found (U.S. Research Information Office website, 2002). 

Karst development in the Door Peninsula region is less active than in warmer regions.  Some caves which formed as the result of dissolution of Silurian dolomite can be seen along the Lake Michigan shoreline of the Door Peninsula at Cave Point County Park (Paull & Paull, 1988).   Other karst features found at other locations on the Door Peninsula are sinkholes, springs, and disappearing streams.   As you can see here, karst features can be dramatic and eye-catching.    

Photo by Alexa Teipel, 2002.  Figure from White, 1988. Click on the figure for a larger version.