Karst Landscapes and Features
A karst landscape is an area in which the landscape is largely shaped by the dissolving action of water on carbonate bedrock (primarily limestone and marble but also dolostone, gypsum and halite). This geological process happens mainly below the ground surface and results in a variety of unusual surface and subsurface features of a range of sizes. Small and medium-sized features include fluted and pitted rock surfaces, clints and grikes, pinnacles, holes and depressions (such as sinkholes, dolines, uvala and poljes), stream sinks, and resurgences such as waterfalls and springs. Larger features include karst valleys, hills, karst cones and towers natural bridges, karst lakes, caves and complex underground drainage systems.
Karst landscapes are distinct from non-karst landscapes because of this processes of dissolution, the permeability of the landscape surface, the presence of a well-developed and open subsurface, fewer surface streams, and an overall calcium-rich environment.
(Source: Image from British Columbia Ministry of Forests)
Karst development begins when rain falls through the atmosphere and picks up carbon dioxide, which then dissolves into rain droplets. Once the rain hits and infiltrates the ground, it percolates through the soil and picks up more CO2 and forms a weak solution of carbonic acid. This slightly acidic water then exploits any existing joints or fractures in the bedrock, gradually dissolving the bedrock and creating larger openings or conduits for the water to flow through. Over many thousands of years, this process eventually creates underground drainage systems and caves. Mechanical processes such as stream corrasion (abrasion) also come into play once subsurface conduits are of a significant size.
(Source: Image from British Columbia Ministry of Forests)
Limestone purity is one of the most important factors in karst development - the purer the limestone, the higher its potential for karst development. It is estimated that Karst landscapes encompass some 10-15% of the earth's land mass and millions of people live in or among karsts. They are considered natural hazards in the sense that they present particular challenges in the design and construction of buildings and infrastructure.
The Cardinal Creek Karst
The Cardinal Creek valley formed within the Champlain Sea basin after its retreat from the region, providing a drainage-way to the proto-Ottawa River. The distribution of sedimentary deposits in the area suggest the karst may have formed prior to end of the last glaciation period. After that time, the Cardinal Creek cut through the surficial sediments down to bedrock, opening up the cave entrances to the karst system.
(Source: Image courtesy of the Cardinal Creek Community Association)
Human activities in the area have had a negative impact on the karst. At some time in the past an artesian well was dug and the creek sink point landscaped. More damaging was the construction of Watters Road which cut a wide swatch through the middle portion of the site and was likely responsible for the burial of one of the original springs. Currently, the karst is under intense pressure as a result of the City of Ottawa's Official Plan Amendment 76 and the forthcoming development of 4,800 homes in Cardinal Village. To date, only the southern portion has received any sort of official designation and protection.
Your Mission
Go to the posted co-ordinates and read the information panels. When you are done, follow the path south to another set of panels. There you will find something interesting in a fenced-off area. Using your observations on-site and the information above (including the Related Web Page), answer these questions:
- Describe in detail the karst features you see in the fenced-off area.
- Approximately how long is the cave and how does it rank with other caves in Ontario?
- What special designation did the southern portion of the Cardinal Creek Karst receive in 2009?
- What impacts do you think might result from housing development close to or over the karst area?
E-mail your answers to me. You don't have to wait to log your visit. If your answers are not correct I will let you know. If it's obvious you didn't visit the site or you don't send your answers in a reasonable amount of time, your log will be deleted. No spoiler photos please.
Warning: DO NOT enter the fenced-off area or any other areas posted Private Property. It is illegal and potentially dangerous to do so.