This is an EarthCache located in the North of Scotland.
If you visit the posted coordinates you will have visited an impressive waterfall known as the Wailing Widow's Fall or more formally as Loch na Gainmhich Waterfall.
The small loch of Loch na Gainmhich lies just south of Loch Glencoul and Kylesku, off the A896 road from Loch Assynt. The outflow from the loch tumbles almost straight down the waterfall to a narrow gully that is almost completely hidden from view.
There are two sets of parking locations, one to visit the waterfall from above and one to visit it from below, you will need to visit both locations to answer the questions required to log this EarthCache.
As this is an EarthCache you will need to send me your answers via email or the message centre to claim a find.
The Geology Lesson
The main theme of this Earthcache is understanding the nature of Metamorphic rocks, there are some supplementary questions about the waterfall to attempt.
Waterfalls are classified into different types depending on the way they descend.
Thanks to Greg (Meltdiceberg) for permission to use this image.
By visiting both waypoints you will be able to gather the information required to answer this EarthCache.
The rock that you are observing.
The rock that the waterfalls cut through is quartzite.
Quartzite is a hard metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red.
The grainy, sandpaper-like surface becomes glassy in appearance. Quartzite is very resistant to chemical weathering and often forms ridges and resistant hilltops. The nearly pure silica content of the rock provides little material for soil; therefore, the quartzite ridges are often bare or covered only with a very thin layer of soil and little vegetation.
Metamorphic rocks
Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors. Conditions like these are found deep within the Earth or where tectonic plates meet.
Process of Metamorphism:
The process of metamorphism does not melt the rocks, but instead transforms them into denser, more compact rocks. New minerals are created either by rearrangement of mineral components or by reactions with fluids that enter the rocks. Pressure or temperature can even change previously metamorphosed rocks into new types. Metamorphic rocks are often squished, smeared out, and folded. Despite these uncomfortable conditions, metamorphic rocks do not get hot enough to melt, or they would become igneous rocks!
Common Metamorphic Rocks:
Common metamorphic rocks include phyllite, schist, gneiss, quartzite and marble.
Foliated Metamorphic Rocks:
Some kinds of metamorphic rocks -- granite gneiss and biotite schist are two examples -- are strongly banded or foliated. (Foliated means the parallel arrangement of certain mineral grains that gives the rock a striped appearance.) Foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that pressure was applied.
Non-Foliated Metamorphic Rocks:
Non-foliated metamorphic rocks do not have a platy or sheet-like structure. There are several ways that non-foliated rocks can be produced. Some rocks, such as limestone are made of minerals that are not flat or elongate. No matter how much pressure you apply, the grains will not align! Another type of metamorphism, contact metamorphism, occurs when hot igneous rock intrudes into some pre-existing rock. The pre-existing rock is essentially baked by the heat, changing the mineral structure of the rock without addition of pressure.
The questions
Q1. Visit the top of the waterfall, from your observation of the rocks at this location, do you think the Quartzite is foliated or non-foliated ? Explain why ?
Q2: Using the information in the listing about Quartzite and via your own observations, can you describe the rock at the base of the waterfall. Please describe the hardness, texture and colour ?
Q3: Describe the key differences between the wet rock in close proximity to the waterfall and the dry crags to the side where the water has not been in contact?
Q4: From the information given about waterfalls and using your observations, can you identify the type of waterfall you are visiting ?
Q5: Using your GPS take an elevation reading at the top of the falls and at the bottom. What is the elevation at the top of the falls and at the bottom ? How far do the falls drop between these points ?
Q5 (optional): Include a photograph of yourself or your GPS with the waterfall behind you and another near to the top of the falls. Please only do this if you feel safe and confident at the locations.