Special thanks to Plasma Boy for helping me with this earthcache.
To log this earthcache, don’t worry about answering all questions perfectly correct. Simply send your best attempts at answers for the questions in a private message to me, (the cache owner), and then go ahead and log it as found.
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- [REQUIRED] Please post a photo in your log of yourself or a personal item that shows beautiful Grand Pré in the background to prove you visited the site.
- At the area surrounding the cache coordinates, what is the level of the land as compared to sea level?
- If the dykes were all removed, what do you think would happen to the land at Grand Pré?
The Grand Pré area has a long and rich environmental history. In July 2012, UNESCO recognized the Landscape of Grand Pré as a World Heritage Site.
Grand Pré was an Acadian settlement from 1682 to 1755. Much of the low lying agricultural lands visible from the look-off owe their origins to the Acadian settlement. Originally salt marshes, the Acadians claimed these fertile agricultural lands from the Bay of Fundy and its highest tides in the world by a series of dykes and aboiteaus. These lands have essentially been continuously farmed and augmented by generations of New England, Loyalist, and Dutch farmers. Grand Pré National Historic Site of Canada, operated by Parks Canada, commemorates the historical settlement, the deportation of the Acadians between 1755 and 1762, and the role of this site as the heart of Acadie.
For much of the 4000 years that the Minas Basin has been tidal, salt marshes have been present, building up continuously to keep pace with sea level rise. This vertical increase results from the trapping of sediments, together with absorbed nutrients, by salt marsh plants as the tide rises twice each day. Thus a Fundy salt marsh represents thousands of years of biological production: the plant roots, sediments and nutrients have been stored in the marsh over a geological timespan, producing an accumulation of fertile soil. With the coming of the Acadians, and the dyking of some of these marshes, that fertility became available for agriculture. Indeed, topsoil is on average four and a half metres deep. Although the low permeability of the sediment makes it difficult for salt to be washed out of the soil, farmers were still able to grow shallow-rooted crops. Prior to the Acadian settlement, human use of the Bay of Fundy was mainly through the capture of animal life – shellfish, fish, birds and mammals.
They created farmland by transforming marshland rather than by clearing woodland. Over time, they cleared land from the uplands to make way for the buildings, roads, and paths, as well as to create some farmland and allow access to the woodlots. From these lots they extracted the building material for their houses, barns, aboiteaux, and dykes. From the 1680s onwards, three generations of Acadians gradually enclosed and converted the marsh (la grand pré). The resulting agricultural abundance brought prosperity to the local community and allowed it, along with other similar Acadian communities, to enjoy a remarkable population growth.
- They were the only pioneer settlers in that era to farm so extensively below sea level.
- The great fertility of the dyked marsh was an important key to the region's success.
- The extreme tides at Grand Pré make mechanized draining unnecessary, because the low tide is well below the level of the dykelands
The technology that the Acadians used to transform wetlands and marshes could not have been simpler: special spades, pitchforks, axes, and hollowed-out tree trunks. Much more important than the tools was the ingenuity of the people to read the natural drainage systems of the marshes and then to build dykes that channelled the flow of those creeks in only one direction, discharging into the sea. One element of the Acadians’ success was to use sod cut from the original wetlands in their earthen dykes. In a process similar to peat extraction in western Europe, special spades were used to cut bricks of sod in specific sizes and shapes that were then assembled to form the dyke. The grasses and rushes in the sod could withstand being covered by salt water for many hours each day. They also had deep and densely matted root systems that anchored them when the sea water swirled over them, protecting the exposed sides of the dykes at high tide. Cutting the sod and assembling the dykes were a communal undertaking because of the skills, efficiency and speed the work required.
Illustration of a cross-section of the dykelands at Grand Pré, including the tidal range, salt marsh, aboiteau system and fields. Note the aboiteau refers to the section of the dyke surrounding the sluice; this cannot be accurately represented in a cross-section, but can be seen. Additionally, the tidal zone at Grand Pré includes mudflats that extend for hundreds of metres. In order to illustrate the mean tidal range, this diagram considerably reduces the mudflats.
Along with using the strong, dense plant growth in the sod, the Acadians took advantage of the natural drainage patterns of the marsh by building aboiteaux in the small creek beds that drained the marshes at low tide. The aboiteau, a term used in Acadie, refers to the section of the dyke surrounding the sluice, as well as to the completed dyking project. The sluices each had a clapet (clapper), a wooden valve that allowed fresh water out of the sluice and into the river or bay at low tide but did not allow sea water back in during high tide.
Once a section of marsh was enclosed, the fresh water from rain and snow melting gradually washed the salt out of the top layers of the soil. The desalination process generally took two to three years for each plot of dyked land. The aboiteau approach used by the Acadians was imaginative and ingenious, an adaptation of techniques used in Europe and elsewhere for centuries before French colonists arrived in North America.
The Acadians would go on, until 1755, transforming many marshes of different sizes along tidal rivers and various coves and bays around the Bay of Fundy, in many parts of today's Nova Scotia and New Brunswick. Acadians came to be known as défricheurs d’eau (water pioneers), to distinguish them from other colonists in North America who created farmland by clearing the forest.
Though the Acadians used marsh enclosures to give themselves agricultural land in many different areas, the high tidal range at Grand Pré presented exceptional challenges. Along the Annapolis Basin, where the first Acadian dykes were erected, the tidal range varies from 4 metres to a maximum of 8.5 metres. Within the Minas Basin at Grand Pré, the mean tidal range is 11.61 metres, and the highest tides in the basin reach more than 16 metres. To the Acadian dyke builders, countering this churning volume of sea water required toughness and ingenuity. They had to devise a building technique that would not wash away as the dyke was being built, dexterity to assemble the different parts of the dyke effectively, collective coordination to transform large tracts of lands quickly, and great labour to build large dykes that could withstand the pressure of such formidable amounts of water
Information for this earth cache is in part from the website The landscape of Grand Pré. http://www.landscapeofgrandpre.ca/home.html
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