WATERFALLS
Waterfalls most commonly form when a river is very young, usually where water flows over different types of rock, principally from a harder to a softer and more easily eroded rock.
Where the water passes over the harder rock, erosion is slow, but the softer rock is eroded away much more quickly forming a drop, either cascading with the underlying form of the harder rock, or plunging vertically into a bowl-shaped pool below.
If the harder rock forms a layer over the softer rock, then often the softer rock will undercut forming a rock shelter with the water free-falling into the plunge pool.
Streams generally become wider and shallower just above waterfalls due to flowing over the rock shelf, and there is usually a deep area just below the waterfall because of the kinetic energy of the water hitting the bottom.
TYPES OF WATERFALLS
There are 12 generally accepted types of waterfalls, although some waterfalls can fit more than one type.
Block - Water descends from a relatively wide stream or river.
Cascade - Water descends a series of rock steps.
Cataract - A large, powerful waterfall.
Chute - A large quantity of water forced through a narrow, vertical passage.
Fan - Water spreads horizontally as it descends while remaining in contact with bedrock.
Frozen - Any waterfall which has some element of ice.
Horsetail - Descending water maintains some contact with bedrock.
Plunge - Water descends vertically, losing contact with the bedrock surface.
Punchbowl - Water descends in a constricted form and then spreads out in a wider pool.
Segmented - Distinctly separate flows of water form as it descends.
Tiered - Water drops in a series of distinct steps or falls.
Multi-step - A series of waterfalls one after another of roughly the same size each with its own sunken plunge pool.
PAPUA FALLS
Also known as Wigmore Falls, Papua Falls is the only waterfall on the island of Rarotonga. Just above the falls is a water intake so it is important to stay away from the water upstream of the intake (no swimming, washing, etc).
Papua Falls can be reached by a short drive or walk from the main (southern) road, or is a welcome stop on the cross island trek that also passes another earthcache at Te Rua Manga (The Needle).
THIS EARTHCACHE
To log a find on this earthcache you must visit Papua Falls and perform the tasks outlined below:
1 - Describe the type(s) of waterfall this waterfall would be classified as. Justify your answer(s). This answer should be emailed to the cache owner.
2 - Estimate both the height of the waterfall (if possible, use GPS readings at the top and bottom) and the depth of the plunge pool. These answers should be emailed to the cache owner.
3 - Take a close look at the rock in this location - the rock face over which the waterfall cascades, and the walls of the gully carved by the falls. Describe the texture and appearance of this rock.
4 - Why do you think this is the only significant waterfall in the Cook Islands? Think about the other islands and justify your answer. This answer should be emailed to the cache owner.
5 - Take a photo of the falls when you visit to show the amount of water coming over the falls. This task is optional, but can be used to give an ongoing record of the water volume over the falls. This photo, if taken, should be uploaded with your online log.
You can log this cache straight away after you have emailed your answers to the cache owner, no need to wait for confirmation. Please include the name of this earthcache in the email - you'd be surprised how many people forget. Also, when contacting us with answers, if you want a reply, please include your email address. Any problems with your answers we'll be in touch.
Happy Earthcaching!
nzkeko