The Shifting Sands of Chantry Dunes EarthCache
Hidden : 6/3/2011
Difficulty:
2 out of 5
Terrain:
2 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:


Lake Huron Dunes

Dunes have formed along the eastern shores of Lake Huron since the subsidence of post -glacial Lake Nipissing 6000 years ago. This physiographic region is known as the Huron Fringe, which streches approximately 320 km along the eastern shore of Lake Huron from Sarnia to Tobermory. Prevailing northwesterly winds have concentrated dune deposits along these eastern shores, influenced by onshore and nearshore topography. There are 5 major dune systems along Lake Huron’s main basin; Pinery- Ipperwash, Point Clark-Lurgan, Inverhuron, Southampton and Sauble Beach. Of these systems, only Pinery-Ipperwash has an active sediment supply, with eroding bluffs and nearshore lakebed, as well as minor contributions from rivers and gullies. The remaining dune systems are relict sand deposits; remnants with no active, viable source of sediment inputs.

What are Dunes?
A dune may be simply defined as a mound or ridge formed by the deposition of sand. These geologic formations develop when an abundance of sand combines with wind, vegetation and geography. Since the compostition of dunes is fine sands, they are vunerable to erosion - from stormwaves and wind.

Beaches and Dunes

Beaches and dunes are a system. Dunes require a beach for their sand supply and beaches need dunes for their sand reserves to maintain its form and function.

Dune Formation

The beaches and dunes at this location were created due to the topography of the coast. Southampton's beaches and dunes have formed in the lee of Chantry Island and its shoals. This protective barrier has allowed sand, originating from the Saugeen River, to be deposited in the shadow of the island.



Sand is continually being eroded and deposited on the shore by waves. Storm waves will erode the beach, taking the sand offshore and forming a sand bar. The sand bar acts as a temporary protective berm, absorbing wave energy the would otherwise reach the shore causing even more erosion. Once the storm subsides, gentle waves will gradually bring the sand from the sand bar back to the shore and re-deposit on the beach. Once onshore, the sand is then moved onto the dune by wind.

Dunes form when sand is carried, by the wind, from the beach towards the land. Wind transports the sand in three ways: suspension, saltation and surface creep

Suspension: the lifting of smaller, lighter sand grains into the air and carrying them for long distances.

Saltation: heavier grains moves by 'jumps' and 'hops' along the beach surface.

Surface Creep: sand particles being rolled along the surface as a result of wind forces or impact of descending saltating particles.



The major forms of sand transport within this dune are saltation and surface creep. Very fine sand able to be carried by suspension are usually carried beyond these dunes.

To Log this Earthcache:

You will need to navigate to each of the 4 way points associated with this Earthcache to answer the following questions. At no time will you need to leave the defined path to get the anwers. Please e-mail the answers, do not post them with your Found log.

QUESTIONS:
1. At waypoint #2, using the information from the cache page and the sign, what method of sand transport do you think is responsible for the sand at this waypoint?

2. At waypoint #3, what significant land form lies directly to the west of this location?

3. At waypoint #4, from the sign, determine what part of the dune you are in.

4. At waypoint #5, you should be standing in a path that connects the two beaches. Take a look around and take note of your surroundings, take pictures if you need to, then using the graphics on the cache page, describe what kind of dune formation you are standing in?

5. Have fun, your Earthcaching!

Additional Hints (No hints available.)



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