Wied il-Mielaħ Window EarthCache
-
Difficulty:
-
-
Terrain:
-
Size: 
(other)
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
Now that the Azure Window on the West coast of Gozo is sadly gone, another beautiful spot with a natural rock arch hopefully can fill the empty space for cachers.
Natural arches, natural bridges or rock arches are natural rock formations. The opening of the arch is completely surrounded by rock. The thickness of the rock formation generally resembles its height and width. There are great differences in size, starting from a few centimeters up to 100 meters and more. The largest natural arch is the Xianren Bridge in China, with a span of approx. 122 meters (400 ft).
Natural arches commonly form where inland cliffs, coastal cliffs, fins or stacks are subject to erosion from the sea, rivers or weathering. Most natural arches are formed in sandstone or limestone with steep, often vertical, cliff faces.
Natural arches only form under certain circumstances. Primarily, the rock or rocks involved, the form of the rock in which erosion takes place and the different erosional mechanisms are relevant. Erosional forces include: water, changes in temperature, tectonic and gravitational forces. Wind normally doesn't play a major role but can be a factor in shaping the arch later. One example can be the abrasive effect of sand which is transported by wind and grinds the rock.
Amongst others, the following mechanisms can promote formation of rock arches:
- Tectonic activity can lift rock and thus lead to cracks and fissures in the rock which are then widened by water cutting further into the ground. This can especially lead to formation of rock arches if water flows along bedding planes in layered rock.
- Glacial activity can result in steep rock faces; deglaciation then promotes erosion by large quantities of water. - Meandering rivers can lead to a convergence of river loops and later to a cut-through between neighbouring meanders.
- Subterranean rivers can form by karst formation, formation of caves and inkasion of the latter, thus also forming arches.
- Volcanic activities can result in formation of lava tubes; collapses again lead to formation of rock arches.
- Erosion by breaking of waves, which is enforced by sand and gravel transported by the waves, is a major effect in the surf region of coasts. This might lead especially to increased erosion in the lower part of a rock formation, while the upper parts are less influenced.
- Chemical influences and weathering by temperature changes (alternating periods of frost and thawing) lead to destabilisation of rock.
(visit link)
The image ((c) Mineralienatlas.de) shows a schematical view of the formation of a rock arch by wind corrasion.
Wied il-Mielaħ Window is located at the end of Wied il-Mielaħ Valley and is - in contrast to the well-known Azure Window, which is now gone - a relatively unknown natural arch due to its remote location and the narrow road.
The street from Għarb directly leads down to the coast with some parking bays available along the road and on the plateau. The path to viewpoint 1 leads along the cliff on the eastern side of the inlet down to the water line opposite the window. The local city council plans to upgrade the path to allow access for divers. At the moment, however, the path is blocked by a gate since the rails in the lower part are missing. Please respect the gate for your own safety. You can see everything you need for the questions from the gate.
The arch can be walked and is used by climbers. Several climbing routes with fixed belay points are established on the sea side pillar.
(visit link)
To log the Earth Cache, please answer the following questions via my profile (please use Message center, not email). Please do not include answers in your log. You don't have to wait for log permission, I will contact you if anything is wrong.
1) Estimate the dimensions of the arch (clearance between sea level and roof, clearance between side walls)
2) In which type of rock did the arch form?
3) Starting from the description above and your observations at the viewpoints, name the criteria which assume a major role in the formation of Wied il-Mielaħ Window and why. Compare to the schematic view above. Do you think that corrasion had major influence in the formation of Wied il-Mielaħ Window?
4) Go down to viewpoint 1 (down the stairs as far as possible). Take a look at the prominent round hollow structures in the river bed. What are they called and how do they form? How could they be linked to the formation of the window?
5) Post a picture of your choice of the arch (not mandatory).
Be careful when approaching the area, especially with children, the cliffs are steep. Enjoy your stay!
~~~~~
Take nothing but pictures, leave nothing but footprints, waste nothing but time!
Additional Hints
(No hints available.)
Treasures
You'll collect a digital Treasure from one of these collections when you find and log this geocache:
Loading Treasures