Limestone cliffs and caves line the coast of Niue and cliff-encircled chasm pools are popular destinations with tourists and locals.
This place, closed by the village of Hikutavake, reputed to be the exclusive bathing pool of Niuean royality in times gone by. Maximum water depth is approx 6 meters.
At Matapa Chasm fresh water flowing into the sea mixes with salt water from the sea. This process is also visible. Sometimes you will notice a slight flickering in the water, called a thermocline. This is because fresh water is lighter and essentially floats on top of the salt water until it mixes.
What’s the difference between a Chasm and a Gorge?
As nouns the difference between chasm and cavern is that chasm is a deep, steep-sided rift, gap or fissure; a gorge or abyss while a cavern is a large cave.
Very often a Chasm is rhomboid in shape (diamond-shaped), that forms deep in the crust through transverse faulting of two blocks.
A Gap should be referred to as a Water Gap, by definition a Water Gap is a gap that flowing water has carved through a mountain range or mountain ridge.
So what is a Gorge?
The term "gorge" comes from the french word gorge, which means throat or neck.
By geological definition a gorge is a deep, narrow valley with very steep sides, usually where a river passes through mountains or an area of hard rock. Very often a gorge is created by erosion of the sturdy limestone cliffs:
- by wind erosion: wind can either blow away small particles and thus remove material - or erode rocks through carried particles (sand, dust) or
- by river erosion: flowing water (e.g. rivers) creates depressions in the surface.
A gorge is often smaller than a canyon, although both words are used to describe deep, narrow valleys with steep sides, rocky walls located between hills or mountains with a stream or river running along their bottom.
It’s a place usually where a river passes through mountains or an area of hard rock.
In summary one could say, a gorge is is a deep narrow passage with steep rocky sides; a ravine.
So what's a ravine?
It's very simple: a ravine is a deep, narrow gorge with steep sides.
And what’s an abyss?
That’s easy: An abyss is a deep or seemingly bottomless chasm.
It's still easy so far, right? But let's explain it in order
A cavern is just one type of cave. It‘s a type of cave that grows "speleothems." Speleothems grow because stuff keeps getting added to make special formations.
But for heaven's sake...what’s a den?
The den is a small cavern or hollow place on the side of a hill, or among rocks; especially, a cave used by a wild animal for shelter or concealment while the cave is a large, naturally-occurring cavity formed underground, or in the face of a cliff or a hillside
The process of Erosion
Erosion is a transformation in soil and rocks, or rather, the process of erosion, transport and sedimentation of soil and rocks. It occurs naturally but can be intensified and even provoked by human action.
The classification of erosions is conditioned by factors such as the type of erosive agent (water, winds and living beings), the relief, the geological structure of the eroded terrain and the previous processes to which it was subjected.
Here are some of the main types of erosion:
• Rain erosion
It is the type of erosion caused by rainwater. In fact, precipitation water is the major responsible for 7 processes. Rain causes the natural erosion of the rocks and aggravates the process of erosion of soil degraded by human action. The proportion of erosion, therefore, depends not only on the intensity and volume of rainwater, but especially on the type of treatment given to the terrain.
• River erosion
It is caused by the water action of the rivers and streams and deepens the valleys in relation to the surrounding lands. River erosion is aggravated when the riparian forest is removed, because the banks are worn by the force of the waters, which intensifies the silting processes of the rivers.
• Marine erosion
Caused by the action of the waters of the seas and oceans, marine erosion causes the erosion of coastal rocks and soils, contributing to the formation of beaches and coastal landscapes, such as the cliffs.
• Wind erosion
It is caused by the action of the winds, which, little by little, are displacing particles from rocks and soil and acting in the transport of sediments. This type of erosion is much slower than that caused by water and is more noticeable in places where the climate has low averages of precipitation and humidity.
• Glacial erosion
In regions where there are negative temperatures, there is freezing of the water contained in the surface and in the underground. When the water freezes, its volume increases - it expands -, and this expansion generates the movement in blocks, which causes the material to move. In addition, the water particles contained in the soils when frozen also move, contributing to the erosive processes in these places.
• Gravitational erosion
As its name suggests, this type of erosion occurs on terrain with high slopes, such as in mountain ranges. Materials from the upper areas, by virtue of gravity, "fall" into the lower areas. Depending on the protection of soil or rock and the type of material, this process can be gradual or move large blocks of rock.
Source references:
https://wikidiff.com/chasm/gorge
https://mapcarta.com/20418160
https://www.getamap.net/maps/niue_[_new_zealand_]/niue_(general)/_matapachasm/
Now you have learned something about the different geological terms and how to distinguish between them.
To log this EarthCache please wander around and look at the area and what is available to you visually, consider the information given and perhaps if you need to do some research of your own, then message me with the following answers to the best of your ability
After all: The question of all questions is why do they call this place Matapa Chasm?
Tasks:
1. Do you think Matapa Chasm is correctly named as a Chasm? Please explain in your own words why or why not.
2. Look at the rocks on the left and right. Do you see deep grooves? What process is believed to have created Matapa Chasm?
3. Please explain in your own words how a thermocline is formed
4. A picture of your team, your mascot or GPS at Matapa Chasm is mandatory.
You are welcome to log your answers straight away but please message or Email me with your answers. I'll let you know if anything is unclear. Please don't forget: the answers must be received within 10-14 days or the log may be deleted.
There is an information sign, but it is not needed to answer the questions.
Caution: It is not necessary to go or swimm into the Chasm to answer the questions, even if it is worth. As the track can at times become quite slippery caution is advised especially when entering the pool.
Enjoy your stay