Spilion tou Xepitira EarthCache
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The Spilion tou Xepitira is a rock arch .
It was formed by the force of erosion.
Liquid water / rain in the spring and frost shattering in the winter formed this unique erosiv structure !
Spilion tou Xepitira is inside the Samariá Gorge on the island of Crete .
General discription
The gorge is in the prefecture of Chania in southwest Crete. It was created by a small river running between the White Mountains (Lefká Óri) and Mt. Gingilos. The hiking trail to Mount Gingilos is part of the European Hiking Trail E-4.The walk starts right next to the cafe which is located above the entrance down to the Samaria gorge . You have to climb on a well-developed hiking trail for about 60 minutes . First you are passing through bizarre rock formations and an ancient gnarled cypress tree then you arrive to the large arch .The hiking trail passes right through this cave doline !
The entrance is free !
Geology
The island of Crete was during the Paleocene-age (65.5 to 55.8 million years ago) part of the Aegean mainland. Its present form, however, began only with new ground motion and the quaternary calanques the Pliocene era (before 5.3 to 1.8 million years ago) to emerge. These tectonic processes cut the island in its unusual, elongated narrow shape on the Aegean continental plate. New breaks and shifts in the earth's crust created the textured surface shape of the island in its main features and the final present form was created by last movements of the earth's solid crust. The latest rock layers are deposits from the Quaternary (1.8 million years ago)
Geomorphology
Inside the george you will see some karst formations .
The karstification of a landscape may result in a variety of large or small scale features both on the surface and beneath. On exposed surfaces, small features may include flutes, runnels, clints and grikes, collectively called karren or lapiez. Medium-sized surface features may include sinkholes or cenotes (closed basins), vertical shafts, foibe (inverted funnel shaped sinkholes), disappearing streams, and reappearing springs. Large-scale features may include limestone pavements, poljes and blind valleys. Mature karst landscapes, where more bedrock has been removed than remains, may result in karst towers, or haystack/eggbox landscapes. Beneath the surface, complex underground drainage systems (such as karst aquifers) and extensive caves and cavern systems may form.
The spilion structure may caused in three steps :
Sediments spall into a little cavity
As spalling continiues , the covering sediments form a struktural arch
The cavity migrates upward by progressive roof collapse .
In this special case the back of the cave tumbled down and became a doline . An the front part became a natural bridge .
Picture source : USGS
Chemisty
Main dissolution mechanism :
The carbonic acid that causes these features is formed as rain passes through the atmosphere picking up CO2, which dissolves in the water. Once the rain reaches the ground, it may pass through soil that can provide much more CO2 to form a weak carbonic acid solution which dissolves calcium carbonate. The sequence of reactions involved in the limestone dissolution are the following:
This is the main dissolution mechanism of calcium carbonate in limestone.
Hydrogeology
1400 mm Rainfall in Wintertime !!!
The tourist season on Crete (from April to October) is also the dry season and most summer visitors do not realize that Crete, especially the West of Crete, has more rainfall per year than most areas of northern Europe: it may rain only 50 or 60 days a year but it really pours! The heavy rains that come down to the high raised mountains of Crete have a strong physical and chemical attack on the bedrock. The ground is very little overgrown ,so the rain water continuing floods unimpeded soil particles off the surface. The strongest rains go down in the wintertime , but cold water can accumulate more carbon dioxide , so the rain in the winter it has a stronger chemical dissolution impact to the bedrock .
If you like go ahead about 15 minutes to visit the spring of Linoseli. The spring water is superb and it is the only water on the way.
To log this cache as a found ...
1.) What kind of bedrock is the arch made of ?
Raise it a few stones from the ground up and consider them !
Are the stones hard , fine -grained , and they collide with the sound of metal ? Then you have a kristalline Limestone like Dolomit ! Are the stones more layered and grained and they sound hollow when collide ? Then you may be have a platy limestone !
2.) What colour has the bedrock ?
3.) What is the altitude difference from the upper entrance to the lower exit of the arch !
How many meters do you measure ? (Use you GPS device ! )
4.) What is the Latin name of the plant that will be presented at the signpost / plate ?
Send me your answers over the e- mail function of GC.COM from my profil page !
You can log immediately after sending the answers !
General behavior :
Don´t leave the footpath ! Protect the environment ! Leave nothing exept sweat and take nothing but pictures !
Some words of warning :
Please don´t wear beach cloth and flip-flop´s. Wear closed walking shoes and protect yourself against the sun with a cap and sunblocker . In summer take some water with you for two hours . The next natural spring is the spring of Linoseli which is 15 minutes ahead .
Additional Hints
(No hints available.)