Choose a Side EarthCache

To complete this Earthcache, you will be visiting both sides of the Bruce Peninsula – approximately 12km apart. Very short hiking time is required to complete this cache (not counting the 12km between sides :) unless you have time to walk that). First visit the posted-co-ordinates and then the one waypoint co-ordinate answering the questions below. Please supervise children around the cliffs and water at all times.

While on the property of the Spirit Rock Conservation Area (87 acres of the Bruce Peninsula), please take extra care to STAY ON THE TRAILS (posted trail map in parking area) and respect the signage. The Conservation Area connects to the Bruce Trails: http://brucetrail.org/pages/trail

If you have some extra time today, you might want to choose a side on the Bruce Peninsula. What do you like best, swimming or hiking? Would you bring: a bathing suit and towel or hiking poles & hiking shoes?

Thanks to the Grey Sauble Conservation Authority for supporting this Earthcache listing.

Photos of you in the area are always nice to see and add to the interest of the geocache page. Please consider adding some of your own.
Favourite: If you like this Earthcache, please consider giving it a favourite point so others will know you enjoyed the experience. Thanks a bunch for visiting ~ hope you had fun.

Questions:
1) Visit the posted co-ordinates, N44 45.844 W81 07.937, (stay on the provided trail to the lookout) and look east toward Georgian Bay:

a – From where you are standing, can any evidence of recent erosion/weathering be seen on the cliff face

b - Estimate the angle of the cliff face slope

2) Visit the waypoint, N44 43.804 W81 16.910, and look west toward Lake Huron

a - Is this beach formed from constructive or destructive waves and what evidence do you see to support this

b - Estimate the angle of the beach slope

3) The earth’s crust is continuing to rebound and raise the land slowly at different rates in different places causing the tilt of the peninsula. Therefore explain in terms of rock erosion, why there is a beach on the downward tilted side of the peninsula and not a cliff?

Those who send answers will receive a bonus.

What can shape water’s edge?

Erosion: Erosion is happening every day. Over time waves, wind and temperature change the landscape. All changes in landform, from the wearing and moving of soil and rock from erosion and weathering, will result in slopes of various degrees. Two examples of erosion below are beaches and escarpments.

THE NIAGARA ESCARPMENT

- the formation of raised rocky cliff shorelines on Georgian Bay:

The Niagara Escarpment a rock ridge, hundreds of meters tall in some areas, form an edge of the Bruce Peninsula on the northern shores of Lake Huron. The total length of the escarpment in Ontario is 700km and travels from the tip of Tobermory to Niagara Falls.

The Niagara Escarpment was formed during the Silurian Period (438 and 408 million years ago) by tabulate coral known as barrier reef limestone. Over time coral, mud and dead animals built up in layers on the ocean floor until these sediments were hardened into limestone (calcium- carbonate). All this happened when the ancient seas were 10 degrees south of the equator and north now was then pointed east. Eventually, high concentrations of magnesium in the water transformed the limestone rock into the present day dolomite rock (magnesium-calcium-carbonate). Once the ancient seas disappeared, the exposed limestone was exposed to weather and erosion.

As waves and wind pounded against the rocks, softer rocks underneath were eroded away and pieces fell off. A harder dolostone cap remained on top much like shelf-shapes without a bottom support. Eventually this harder dolostone was eroded forming rockslides. The cliff face remained. At the bottom of the cliff face a scree slope of fallen rocks build up called a cliff foot. This erosion process is still happening today. The escarpment’s position has retreated from Sudbury, originally, to where it is today.

Erosion has created the cliffs you are standing on, on the east side of the Bruce Peninsula.

One theory suggests that the earth was under enormous pressure from the large heavy glacier suppressing the surface. When the glacier retreated, the crust rebound when the weight lifted and it slowly raised the land level over time. This is called isostatic uplift. Measurements of the Great Lakes show they are gradually tilting downward toward the south and west – on the east side of Lake Huron.

BEACHES

– the formation of slightly sloped sandy shorelines along Lake Huron:

The continuous action of waves pounding against the dolomite rocks under the water breaks the rocks down into particles of sand. Sand is then picked up by waves and deposited in other areas. Waves can build up a shoreline as well as destroy a shoreline.

When waves travel near and parallel to a shoreline, the flowing current attacks the shoreline at an angle and is known as a long-shore current. This current carries sand along. When the wave returns to the large body of water after reaching and being stopped by hitting the landform, some of that sandy sediment is deposited creating, over time, a slope. This is how beaches are formed.

WAVES

Waves can be constructive or destructive depending on the distance between the wave crests. During constructive waves there is enough time between crests and the deposited of materials from one wave will settle before the arrival of the next wave. These materials compact and are more resistant to erosion. These course sediments allow for better percolation, the backwash is therefore not as strong and the beach is steep as a result. Destructive waves have a short time between crests and the lighter sediments do not have time to settle. There is more surface backwash carrying these lighter materials down the beach forming a gentle slope.

Congratulations to RickOnTheRange for FTF!

CedarNCo have earned (GSA) Geological Society of America's highest earthcache level:

Platimum Earthcache Level is awarded by Geo Society .org for visiting and logging 20 or more EarthCaches in 5 or more states/provinces/countries and have created 3 or more EarthCaches.