The falls are spectacular any time of year (although access is trickier in the winter) and a visit to this location can provide amazing insight into the geological forces that not only shaped this beauty of creation, but also into how those same forces make rare metals and valuable minerals accessible to us for commercial use.Just up-river from Lower Myra Falls is the Nyrstar N.V. owned Myra Falls Mine. This mine extracts zinc, copper, lead, silver and gold from the Earth via underground mining, although originally the mines were open-pit. Access to elements is due to ancient volcanic activity on the seafloor. This activity resulted in what is known as a volcanogenic hosted massive sulfide (VHMS) ore deposit.
The VHMS deposit near Myra is a large bowl-shaped basin, created by super-heated water and mineral combinations (hydrothermal solutions) venting into ancient depressions of the land under the ancient oceans. Most of the rock that makes up Vancouver Island was originally formed by such undersea lava deposits, which then became covered in limestone - built up by countless amounts of sea-life and other calcium deposits that turned into stone over time. The VHMS deposit became accessible for mining due to an exposure created by a fault-bounded uplift. This is where the deposit rose above other geological layers closer to the surface of the Earth due to being pushed up to the surface between faults on either side of it caused by earthquake activity.
The creation of Myra Falls is also the result of faulting. Waterfalls are created by faulting when two rock surfaces have an elevation change between them due to the uplift of one as the result of an earthquake. Water moving from the higher surface then drops to the lower surface and erodes the softer material on the lower surface with the extra energy it gains from the drop.
While standing at ground zero, you are observing a fault-bounded uplift that has resulted in a faulting created waterfall. The softer materials at the upper layers (limestone, etc.) have been eroded away by the power of the waterfall to expose the rock that started from the undersea lava deposits eons ago.
Earthquakes along Buttle Lake have caused several faults – each fault can be observed in dramatic elevation differences in the exposed rock.
Observe the rock faces around the “Lower Falls” area of Myra Falls. This is the area at ground zero, where people often dip their feet (or the truly adventurous swim) into the glacial water, and other nearby spots you can observe from here.
Please remember to be very careful when exploring this area as the rocks can be slippery when they are wet – please also stay out of the water where it moves close to the edges as this can also be dangerous.
To log this cache, please answer the following questions, and email your answers to the cache owner. An optional request is to post a photo of you or your caching group at or near ground zero.
- How many significant “cascades” or sections of the waterfall are observed from this location?
- What does each cascade or section suggest about geological activity along this section of Buttle Lake?
Sources for information include: