Streamsinks in the karst rock of the Kourtaliotiko Gorge
The diverse geology of Crete offers a wide range. You can observe many different types of rocks and geological phenomena here. At this point I would like give you an understanding of streamsinks in karst rock.
What does karst rock actually mean?
In geology and geomorphology, karst is known/described as underground and above-ground terrain in carbonate rocks. These arise primarily from weathering provoked by solutions and carbonic acid as well as the precipitation of biogenic limestones and similar sediments with a high concentration of calcium carbonate. Karst rock is often found in Crete. Deeply developed karst landscapes can have completely dry soils despite abundant and sometimes high rainfall. Karst landscapes are subject to an age-related erosion cycle.
What does the term streamsinks mean?
A streamsink (also called ponor) describes the case in which the inflow amount is small enough to be able to pass through the opening and the subsequent cave system without the water accumulating on the surface of the site and at least partially being able to drain off there normally. This manifests itself in the fact that a stream in such an opening literally disappears. It is also possible that only a part of the stream disappears which can vary in size. At another point, the brook comes to the surface again.
This phenomenon should not be confused with a source at the point of exit. Different layers of rock or geological peculiarities favor rare occurrences like this.
What is happening here?
Favored by the karst rock, which has formed a correspondingly large number of cavities in the subsoil, the stream can 'disappear in the mountain' here and reappear at the surface at a different spot.
This erosion process has taken place over thousands of years, creating a second underground path for the stream.
In order to log this earth cache, you have to find out and describe a few things on site.
Please send me the answers BEFORE logging the cache as found. Afterwards you can log immediately. Log entries without answers will be deleted without comment. Prepare yourself accordingly for this earth cache so that you know all questions on site.
You shouldn't drive down to the second station with a normal car!
Please note that you have to overcome a few vertical meters in both directions!
Take enough drinks with you, as it is very hot here, especially in summer.
Here are your tasks:
Go to the coordinates listed.
1) Describe what you see - what is the creek doing here?
2) Describes the rock surface near the stream.
3) Observe the amount of water over a few meters: does it change visibly?
Now go to the second station.
4) Compare the incoming amount of water with question 3. What difference in amount / ratio do you estimate?
5) Does the water that emerges from the rock combined with the water that arrives in the stream correspond approximately to the total amount of water observed at the start?
6) What is the difference in height between your two stations using your GPS device?
7) What is the approximate distance (beeline) between the two stations?
8) Optionally it would be nice if you took a picture of you on site (this is not a log requirement), but please do not spoil.
I hope you enjoy exploring this beautiful gorge.
Many thanks to our friendly Geocacher-Team Patchwork-Rudel for the idea and support at this Earthcache.
Sources: Wikipedia
Much thanks to Patchwork-Rudel for his support.