PLEASE NOTE: this cache is NOT AVAILABLE after a snowfall / when there's been significant snow. You MUST be able to see the waterfall and flow and embankments to complete this cache. THIS IS NOT A NIGHT CACHE.
A first day of winter walk along the easy radial line trail with some nice views. This EC will allow you to view the Mountview Waterfall from (an amazing) bridge along the radial trail. Here, you will explore erosion prevention methods.
To claim this find, be sure to send your complete answers to the CO. Missing or grossly incorrect responses will result in a deleted log. Please be sure to read all the logging requirements. NO group responses - individuals must send their own answers and post their photos with their logs. Thank you.
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Waterfall Formation and Erosion
A waterfall is a feature of erosion found in the youth stage of a river. Waterfalls are found in areas with bands of hard and soft rock (otherwise known as resistant and less resistant rocks). The hard rock takes longer to erode than the soft rock (differential erosion) so the river erodes the land at different rates. Please see the attached photo of waterfall formation. Alternatively, you can access a link to a website here.
The 3 characteristics of waterfalls are:
- Hydraulic action – when the sheer force of the water gets into small cracks and breaks down the rock.
- Corrasion – when the river bed and banks are eroded by the load hitting against them.
- Corrosion – when the river water dissolves minerals from the rocks and washes them away.
There are a number of natural forces that lead to erosion including wind erosion, frost action, soil creep and slumping, but the most common and powerful source is water. A stream's velocity increases as it nears a waterfall, increasing the amount of erosion taking place. The movement of water at the top of a waterfall can erode rocks to be very flat and smooth. Rushing water and sediment topple over the waterfall, eroding the plunge pool at the base. As the water hits the plunge pool it will erode it by both hydraulic action (the force of the water against the bedrock) and by abrasion (where the material carried by the river acts like sandpaper against the riverbed). Eventually, the overhang will collapse due to the erosion of the soft rock beneath it.
Soil Creep: Soil creep defines the slow mass wasting process of soil on a slope, under the influence of gravity.
Slumping: A slump is a form of mass wasting that occurs when a coherent mass of loosely consolidated materials or a rock layer moves a short distance down a slope. Movement is characterized by sliding along a concave-upward or planar surface.
Ice: Cycles of freezing and melting push ice onto the shoreline. Ice can cause significant shoreline damage.
Storm water: Storms remove or displace loose layers of soil causing sheet erosion.
Sheet erosion: Sheet erosion occurs as a shallow 'sheet' of water flowing over the ground surface, resulting in the removal of a uniform layer of soil from the soil surface. Sheet erosion occurs when rainfall intensity is greater than infiltration (sometimes due to crusting). Rarely seen but accounts for large volumes of soil loss.
Erosion Prevention Methods
- Revetments: an engineering technique used on a sloping surface or creating a sloping surface using stone, concrete or other material that creates a slope to absorb the energy of incoming water (see attached image);
- Rock armour/rip rap: large boulders placed in front of a cliff or slope to deflect (wave) energy away and protect the shoreline from erosion (see attached image);
- Gabions: a cage-like structure filled with rocks or concrete (see attached image).
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Questions:
1. At the posted coordinates (on the bridge), take an altitude reading.
2. Look toward Mountview Falls. Based on the cache description, what types of erosion have likely occurred?
3. Look toward Mountview Falls. Based on the cache description, what erosion prevention methods are in place?
4. Describe how effective you believe these methods to be. Provide evidence from your observation of GZ.
5. Post a photo of you/your GPS/your caching name at GZ. Be sure to have both the bridge and Mountview Falls in your photo. NO spoilers, please.
Enjoy! I look forward to reading your responses. IF you are delayed in sending your answers, please post a note until you are able to send me your answers. I reply to all answers sent.