Cranberry Marsh is a coastal wetland on the north shore of Lake Ontario in Whitby. Under the protection of Central Lake Ontario Conservation Authority (CLOCA), this wetland plays a vital role in the protection of fish, bird and animal habitat along the Lynde Creek watershed.
Logging Requirements:
To log this earthcache you need to answer the following questions and send the answers to my profile. Please include the names and number of people in your geocaching group. Once the answers have been submitted by your group, you are free to post your found log. Logs submitted without answers within 5 days risk being deleted. If you are travelling, please indicate that in your log and when you plan to submit the answers.
1. Based on the information contained in the narrative determine if this wetland is protected by a Barrier Beach or Ridge and Swale complex? Explain your answer?
2. Is there free flowing water moving between the marsh and the lake or is the flow of water going in one direction and if so is water flowing from the marsh to the lake, or the lake to the marsh.
3. Is there evidence of a system modifier and if so, what type?
4. How was this wetland created?
Great Lakes coastal wetlands can be divided into three specific systems, based on their hydrologic source and connectivity to the lake. These are Lacustrine system wetlands, Riverine system wetlands and Barrier-Protected wetlands.
Cranberry Marsh is a Barrier-protected wetland that has become separated from Lake Ontario by a barrier beach or other barrier feature. Barrier beaches are formed when sand deposits are pushed up onto the shore from wind and wave action, cutting off a shallow lagoon or wetland.
Barrier-Protected wetlands can be further broken into two categories:
Barrier Beach lagoons are wetlands that form behind a sand barrier. Due to the barrier, mixing of Great Lake waters and coastal erosion is reduced as the barrier protects the wetland from storm surges, wind and wave action. Multiple lagoons are not uncommon depending on the drainage coming from one or more streams that empty into the lagoon. These wetlands can be found at the east end of Lake Ontario and on the Bayfield Peninsula in western Lake Ontario.
Swale Complexes occur between recurved fingers of sand spits that can occur between beach ridges. They are known as sand-spit swales and ridge and sand swale complexes and are common with some of the larger sand spits of the Great Lakes. Within these sand spit formations, embayments can remain attached to the Great Lakes.
Ridge and swale complexes are a series of barrier beaches which are separated by narrow swales. They are common in embayments where sediments form in response to periodic fluctuations in lake levels. Some examples include Ipperwash on southern Lake Huron, Manistique and Thompson embayments on Northern Lake Michigan, and Tahquamenon and Batchewanna embayments on Lake Superior.
A rare type of swale complex is a tombolo which has been known to form in some areas of the Great Lakes. A tombolo is defined as an island(s) attached to the mainland by barrier beaches made of sand and gravel, sometimes consisting of one or more lagoons with deep organic soils. Sometimes this feature can be classified in the swale complex category depending on the dominant geomorphological features. A good example of a tombolo in Lake Ontario is Presqu’ile near Brighton.
System Modifiers of naturally occurring wetlands are sometimes used where hydrology and geomorphology have been impacted by human activities. The impact on the wetland by man has altered the watershed and the wetland has suffered as a result. Man has intervened to restore the wetland back to health by restoring the natural balance between the wetland and the Great Lakes. Some examples of system modifiers include:
a) Dikes which are man-made barriers that are designed to obstruct the inflow or outflow of water, and protect the wetland from lake surges or the effects of wind and high waves. The wetland hydrology is manipulated via water control structures and or pumps
b) Dredging and the construction of Jetties are used to maintain a constant connection with the lake, typically used to allow safe passage of recreational or commercial boating.
***IMPORTANT INFORMATION***
1. This cache meets the CLOCA geocaching guidelines. There is a trail from the parking coordinates which will take you down to the beach. You do not have to leave the beach to find the answers for the questions.
2. Please do not approach the cache from the very end of Halls Rd. You will have to cross private property as there is a house at the end of the road. The trail from the parking coordinates is well maintained and will save you having to bushwhack to the beach or trespass.
3. CLOCA asks for a $ 2.00 donation to visit the marsh. There is an "on your honour" drop box to leave a toonie.
References
1. Summary of Great Lakes Coastal Wetlands Classifications, November 21, 2001 - Research Paper www.glc.org/wetlands/docs/wetlands-class-scheme.doc
2. Cranberry Marsh Restoration Project - Central Lake Ontario Conservation Authority
