Throughout the course of this Earthcache you will learn about the coastal erosion processes occurring here that have lead to the formation of this hanging beach. As with all Earthcaches there is no logbook here; rather you will make observations at the posted sets of coordinates and answer the questions located at the bottom of this cache page in order to log your find.
ATENTION: You must reach the posted cordinate to solve and sign this earthcache as found.
Be careful hiking down the cliff. Take some water to avoid getting dehydrated. And above all, take good shoes.
WHAT ABOUT NUSA CLIFFS?
Cliffs are common coastal features. They are formed by a combination of erosion and weathering, weathering work on the top of the cliff and the base of the cliff erosion wearing away. Steep cliffs formed where the ground consists of hard, more resistant, stone, clear their height is determined by the difference between the sea surface and the level of the soil. Hard rock slowly erode and weather, and less fractured rock is, the better it will resist breaking down. Kelingking Beach is a secluded and scenic beach in the village of Bunga Mekar on the southwestern coast of Nusa Penida Island. One of its most popular landmarks is a plant-covered limestone headland, with massive waves crashing against it. Frozen rocks such as granite and basalt forms such as vertical cliffs along the rugged coast of Nusa Penida. Limestone rock is very strong and can withstand constant cliffs pounded by waves of Indonesian Ocean. Soft rock, such as clay, shale and some sandstone erode more easily and can create a more gentle sloping cliffs, although this is not always the case.
WAVE EROSION
Erosion is the process of wearing away any of the rock along the coastline, in this case we are specifically interested in the rock here at the listed coordinates. Destructive waves are responsible for erosion on the coastline and are responsible for slowly destroying the rock you see here.
There are four types of erosion that can occur on a coastline:
1-Hydraulic action - The waves impact a cliff as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart. Over time, the cracks can grow (sometimes forming a cave). The splinters fall to the sea bed where they are subjected to further wave action.
2-Attrition - this is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded. Also collides with the base of the cliff face.
3-Abrasion - Corrasion or otherwise known as abrasion occurs when waves break on cliff faces and slowly erode it. The repeated action of waves breaking on a cliff is enough to remove material from it over time. If sand & shingle are present in the water, it will act like sandpaper and erosion will take place faster.
4-Solution/corrosion - this is when certain types of cliff erode as a result of weak acids in the sea. The dioxide in the atmosphere is dissolved into water turning it into a weak carbonic acid. Several rocks (e.g. this rock, Limestone) are vulnerable to this acidic water and will dissolve into it. The rate of dissolution is affected by the concentration of carbonates & other minerals in the water.
THAT'S A SEA CAVE? (WAYPOINT)
Sea caves are formed from the forces of the sea, waves seething at the rock face of a coastline sometimes produce huge caverns, which are typically not very long. They are as long as the water reaches. The existence of this cave is not dependent on the kind of rock. Of course, it helps if the rock is weaker. The cave may begin as a very narrow crack into which waves can penetrate and exert tremendous force, cracking the rock from within. Sand and rock carried by waves produce additional erosive power on the cave's walls.
QUESTION TIME! :)
Please use the messaging system to send me the answers of the following questions before you log your cache find. Thank you in advance! :)
1-What is the predominant rock the cliff is made of?
2-Looking torwards the sea, along the left cliff wall far from the beach (REFERENCE POINT) there you can see how the rock from above sea level is more erosioned than the rock of the sea level itself, why?
3-(Go WAYPOINT 1) Along the wall, on your right, you can observe the massive scars of the powerfull wave force. Is interesting there how you can see how high and deep could be these impacts. Estimate the highest point of these scars. What type of wave erosion is more common here?
4-(WAYPOINT 1) Estimate the height and width of the opening of the cave. Do you think this cave could be deeper in the next 50 years? Why?
From June 2019, with the new guidelines, photography may be required to show that the site has been visited. If I do not receive the answers or the photo has not been uploaded, the log will be deleted without notice.
Sources The following sources were used to help develop this earthcache: Wak Laba https://waklaba.blogspot.com/?m=1