During the last Ice Age, a time period spanning from 2.588 million to 12,000 years ago, many glaciers advanced and retreated. As the last glacier melted and retreated across Vancouver Island it left huge chunks of ice. These pieces of melting ice left large indentations in the landscape called kettle holes. A kettle (or kettle hole) is a melt water landform that occurs as a result of blocks of ice calving from the front of a receding glacier and becoming partially to wholly buried by glacial outwash.
Turner’s Bog is a glacial kettle, a formation of a glacial drift. When an ice block melts, a steep-sided depression is left in the earth. This glacial kettle has become a bog. This bog is located north of Kettle Lake Drive, west of the West Shore Parkway, and south of the Sysco Food Warehouse. You can only view it from West Shore Parkway from the the posted coordinates.
Permission to use aerial photo granted from J. Parks, Parks Manager, City of Langford
How Bogs Develop
Bogs are more common in cooler northern parts of the world that receive lots of rain and snow. Glaciers covered this area and as they melted and receded left shallow depressions that filled with water. Sphagnum moss colonized some of these infertile lakes. Everywhere it grows Sphagnum moss changes the environment by acidifying the water. Most plants cannot tolerate this growing condition, but a few can.
Sphagnum moss spreads slowly, old layers sink under the weight of new growth. The cold acidic water is a hostile environment for bacteria and halts them from decomposing dead plant and animal materials. As these layers build, they compress into peat. It takes about 41 years for one inch of peat to accumulate. A shallow moat often forms around the edge of the bog as the peat slowly fills the area in.
Eventually the layers of dead peat and living sphagnum will fill in the lake. Trees grow very slowly due to the lack of nutrients and acidic water. With little soil for anchoring, their trunks become gnarled as they tip in different directions. Trees stretch their roots into the peat looking for firmer, richer mineral soil beneath. You can tell Turners Bog is an old bog by the trees in the center. The moat around the bog is still filling in as the bog ages. Eventually as wetland shrubs, sedges and rushes colonize the edges of the bog, more trees will grow.
Photo taken from West Shore Park Way in September of 2010.
Some 60% of the planet’s total wetlands are peat bogs, which cover an estimated 3 to 4 percent of the world’s land mass. Canada accounts for some of the largest wetlands regions on earth. Peat is an accumulation of partially decayed vegetation matter. Peat forms in wetlands or peatlands, variously called bogs, moors, muskegs, pocosins, mires, and peat swamp forests.
Formation of a Bog
A bog is a habitat where development is influenced by a humid substrate and where litter accumulates more quickly than it can decompose. This is an ecosystem where water circulates little or not at all and in which the litter accumulation rate significantly exceeds decomposition (and humification) rates. In most ecosystems, plants generally produce a certain amount of leaves, stems, and debris. Each year, parts of the plant dies, falls to the ground and litters the floor. During the same year, other organisms, generally bacteria, decompose part of this litter by converting organic plant and animal residue into mineral matter. In a bog environment, water saturation creates a lack of oxygen that reduces the decomposing activity. The annual organic matter that accumulates on the ground exceeds the amount that converts into humus.
To log this Earthcache
E-mail me the answers through my geocaching.com account and post all photos with you log. Once you've sent the email, go ahead and log your find without waiting for a reply from me. I will contact you if there are any problems with your log entry. Please do not give away any answers in your log or your photos!
1) Take and post a picture of your GPS and the bog, at the listed coordinates and answer the following questions.
a) Is there a way you can tell that this is an old bog? Please explain your answer.
b) What color was the water in the moat during your visit?
c) What the length and average width of this moat?
I hope you have fun doing this earth cache!
Congratulations To hopsnbarley and sole seeker
A Shared FTF on September 22, 2010!
This next part is on a peat bogs and I found it fascinating and have included it for your learning enjoyment only.
Peat Bog
In peat bogs, plants often grow under conditions the lack oxygen (anoxic) because of the high water table, but primarily due to the extreme lack of minerals and nutrients characteristic of peat bogs, These conditions explain the frail tree structures that are present. Despite advanced age, these trees are short and small in stature and they develop sparse foliage and produce fewer cones. Sphagnums are the most abundant and widespread bryophyte on the planet and are one of the key elements of a peat ecosystem. Bryophytes are all land plants that are non vascular. They have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They don't have flowers or produce seeds, and reproduce via spores. The term bryophyte comes from Greek bryon, "tree-moss, oyster-green" + fyton "plant".
Mosses, liverworts and hornworts fall into this category.
Peat layer growth and the degree of decomposition (or humidification) depends principally on its composition and on the degree of water logging. Peat formed in very wet conditions will grow considerably faster, and be less decomposed, than that in drier places. This allows climatologists to use peat as an indicator of climatic change. The composition of peat can also be used to reconstruct ancient ecologies by examining the types and quantities of its organic elements.
Under the right conditions, peat is the earliest stage in the formation of lignite coal. Most modern peat bogs formed in high latitudes after the retreat of the glaciers at the end of the last ice age some 9000 years ago. They usually grow slowly, at the rate of about a millimeter per year.
The peat in the world’s peatlands has been forming for 360 million years and contains 550 Gt of carbon.
Types of Peat Material
Peat material is either fibric, hemic, or sapric. Fibric peats are the least decomposed, and comprise intact fiber. Hemic peats are somewhat decomposed, and sapric are the most decomposed. Phragmites peat is one composed of reed grass (Phragmites australis) and other grasses, and is denser than many other types of peat.
Types of Peatland
Six principal types of peatlands are widely recognized. These are:
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Blanket mires: Rain-fed peatlands generally 1 to 3 m deep. They generally develop in cool climates with small seasonal temperature fluctuations and over 1 m of rainfall and over 160 rain days each year (Ireland & UK);
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Raised mires: Rain-fed, potentially deep peatlands occurring principally in lowland areas (Northern Europe, USSR & North America);
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String mires: Flat or concave peatlands with a string-like pattern of hummocks (northern Scandinavia, western USSR & North America);
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Tundra mires: Peatlands with a shallow peat layer (500 mm thick), dominated by sedges and grasses; they form in permafrost areas (Alaska, Canada & USSR);
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Palsa mires: Peatland typified by characteristic high mounds, each with a permanently frozen core, with wet depressions between the mounds. These develop where the ground surface is only frozen for part of the year (USSR, Canada & Scandinavia);
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Peat swamps: Forested peatlands including both rain- and groundwater-fed types, commonly recorded in tropical regions with high rainfall (southeast Asia & Florida)
Characteristics and Uses
Peat bogs were once erroneously considered diseases, unproductive and dangerous. As an ecosystem, peat bogs offer a variety of ecological goods and services and contribute to mankind and the quality of the environment. The annual biomass production they generate represents a vast carbon reserve.
Peat is soft and easily compressed. Under pressure, water in the peat is forced out. Upon drying, peat can be used as a fuel, having industrial importance in some countries, such as Ireland, Scotland and Finland. In many countries where trees are often scarce, peat is traditionally used for cooking and domestic heating. (When dry, peat can be a major fire hazard, as peat fires can burn almost indefinitely (months, years, even centuries, or at least until the fuel is exhausted), even underground, provided there is a source of oxygen. Recent burning of peat bogs in Indonesia, with their large and deep growths containing more than 50 billion tons of carbon, has contributed to increases in world carbon dioxide levels. In 1997, these fires released the equivalent to 13-40% of the amount released by global fossil fuel burning, and greater than the carbon uptake of the world’s biosphere.
Peat is also dug into soil to increase the soil’s capacity to retain moisture and add nutrients. This makes it important agriculturally for farmers and gardeners, and as a natural means of flood mitigation. Peat swamps serve like a natural form of water catchment whereby any overflow will be absorbed by the peat.
Peat softens water by acting as an ion exchanger, it contains substances good for plants and for the reproductive health of fishes, and can even prevent algae growth and kill microorganisms. Peat often stains the water yellow or brown due to the leaching of tannins.
Peat bogs also contain reserves of fresh water, the buffering capacity of which partially regulates peak flow rates during heavy rainfall. Sphagnum bogs are also renowned for their tremendous filtration capacity. Peat bogs can be important for drinking water quality, decontamination of some heavy metals or immobilizing airborne pollutants.