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Kazalo
1. Uvod
2. Kraški relief
3. Škraplje pod Sinjim vrhom
4. Dostop do zemeljskega zaklada
5. Zemeljski zaklad
6. Viri
7. Fotografije
Uvod
Škraplje so podolgovat žlebovi na neporaslih površinah trdega apnenca, ki nastanejo pod vplivom tekoče vode. Škraplje so ena od značilnih geomorfoloških oblik, ki jih najdemo povsod po kraškem svetu in tu Slovenija ni izjema. Gre za od nekaj centimetrov do nekaj metrov dolge kraške oblike, nastale zaradi korozije vzdolž razpok ob ploskvah manjše odpornosti kamnine. Običajno je njihovo površje vodoravno, lahko pa se nadaljujejo v globoke brazde. Če razčlenjujejo skalo v kaos manjših kamnov, jih pravimo tudi griža.
Podoben kraški pojav, vendar v manjših dimenzijah so žlebiči.
Kraški relief
Relief na krasu oblikuje voda, ki kemijsko raztaplja apnenec, kamnino pa voda odnese v obliki raztopine. Ploskovno raztapljanje in zniževanje površja imenujemo kraška denudacija. Ugotovljeno je, da znaša denudacija v naših klimatskih pogojih med 20 in 50 m na milijon let. To pomeni, da se je od rimskih časov do danes površje na krasu znižalo povprečno za 2-10 cm.
Voda prihaja na kras v obliki padavin in ponikalnic. Ponikalnice na kras z neprepustnega sosedstva prinašajo lokalno velike količine vode in je njihov učinek omejen le na bližino ponora. Padavine so enakomerneje razporejene, vendar so v ploskovni razporeditvi raztapljanja razlike, zaradi različne topnosti kamnine in vsebnosti CO2, ki se iz prsti raztaplja v vodi. Voda počasi raztaplja apnenec, ki se pod vplivom organskih kislin v vodi (te pridejo vanjo preko atmosfere ali z izpiranjem tal) raztopi in pomeša z njo.
Drobne kraške oblike nastanejo na površini skale zaradi korozije vode ob stiku s kamnino. Na goli skali nastajajo škavnice, v smeri strmca žlebiči in večji žlebovi. Ob ploskvah manjše odpornosti so nastale korozijske zajede škraplje, ki kamnino ločijo v večje ali manjše bloke. Če je kamnina razčlenjena v kaos manjših kamnov, jih imenujemo griža. Korozijske oblike se oblikujejo tudi pod prstjo. Površina skale je tam gladka, in oblikovana v mehke obline in nenavadne oblike, vdolbke in luknje.
Škraplje med seboj ločijo vmesni grebeni, ki so na določenih mestih lahko izjemno ostri. Take grebene imenujemo skalni noži, teren »posipan« z njimi pa je izjemno težko prehoden. Površju, ki je gosto pokrito s škrapljami pravimo škrapljišče, lahko pa je nadzemno ali podzemno (če je voda izdolbla škraplje pod vrhnjo plastjo prsti).
V primeru, da škraplje nastanejo v skladih apnenca, pokritega s prstjo, ki je bila kasneje odstranjena, je njihova površina lepo zaobljena, brez ostrih robov. Ravno ta zaobljenost površine, kakršna nastaja pod zemljo oziroma rastlinjem, je pokazatelj načina nastanka škrapelj. Kasneje, ko je zemeljski pokrov odstranjen, deževnica in snežnica razjesta gladke površine, kar pa ne spremeni bistveno zaobljenosti površine.
Škraplje pod Sinjim vrhom
Škraplje pod Sinjim vrhom ležijo na severnem vznožju Sinjega vrha (1032 m), ob cesti Col – Predmeja, vrh klancaBinčuše. Po naselju v bližini, Kovku, jih včasih imenujejo tudi kovške škraplje, tu in tam pa se da zaslediti tudi ime škraplje na Gori, Gora je namreč skupno ime za ozemlje med Colom in Predmejo.
Ne glede na ime pa gre za izredno lepo razvite škraplje, ki so nastale v debelih skladih spodnjejurskega (lias) apnenca in predstavljajo tako značilen primer kraškega mikroreliefa, da jih obiskujejo številne šolske in naravoznanstvene ekskurzije. Poznajo jih skoraj vsi slovenski naravoslovci.
Po Gori je še veliko vrst škrapelj in drugih kraških značilnosti, morda še bolj slikovitih, toda kovške škraplje so na izjemno opaznem mestu in tudi zato predstavljajo naravni spomenik državnega pomena. Škraplje so še en nenavaden pojav, ki govori o pestrosti narave na Trnovski planoti. Nekoč je pomemben znanstvenik, geolog, izjavil, da če Slovenija ne bi imela Trnovskega gozda, bi si ga morala kar izmisliti.
Dostop
Do tega zemeljskega zaklada pridete po cesti Col – Predmeja, do enega ali drugega izhodišča pa lahko pridete iz Ajdovščine, do Cola tudi iz Vipave. Do Cola vodi tudi cesta iz Godoviča preko Črnega vrha nad Idrijo.
Škraplje so neposredno ob cesti, zato velja biti pri ogledu pazljiv. V neposredni bližini zaklada sta dve lokaciji, kjer je ob cesti možno parkirati avtomobil (točki PARK1 in PARK2).
Dostop do zaklada je možen skozi celo leto, saj cesto plužijo, vendar pa obisk v času, ko zemljo prekriva snežna odeja, ni smiseln, saj so škraplje takrat zakrite in boste težko odgovorili na zastavljena vprašanja. Poleg tega je hoja po njih takrat tudi nevarna, ker razpoke niso dobro vidne. Priporočamo torej, da si zaklad ogledate v času, ko ni snega, vedno pa bodite pazljivi pri hoji po škrapljah!
Zemeljski zaklad
Za registracijo tega zemeljskega zaklada morate odgovoriti na naslednja vprašanja:
1. Dobro si oglejte škraplje in razmislite o tem, ali so nastale pod prstjo ali na razkritem apnencu? Utemeljite svoj odgovor.
2. Škraplje so razdeljene v dve dobro ločeni polji. Ocenite dimenzije večjega polja (tistega, ki je bližje cesti).
3. Izmerite ali ocenite globino najglobljih razjed. Ali gre za globino okrog 0,3 m, 1,3 m ali 2,3 m?
4. Kot neobvezno nalogo pa naredite fotografijo vas ali vašega GPSja pri škrapljah in jo pripnite vašemu vpisu.
Odgovore pošljite skozi GC profil. Potem lahko zabeležite vaš obisk, ne da bi čakali na posebno dovoljenje. V kolikor bo z vašimi odgovori kaj narobe, vas bomo kontaktirali.
Če ste fotografirali, priložite zanimive fotografije.
Vpisi brez poslanih spremljajočih odgovorov, ali vpisi, ki vsebujejo odgovore na vprašanja, bodo izbrisani!
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Table of Contents
1. Introduction
2. Karst relief
3. Karren below Sinji vrh
4. Access
5. EarthCache
6. Sources
7. Photos
Introduction
Karren are elongated grooves in the bare areas of hard limestone, which form under the influence of running water. Karren are one of the typical geomorphologic forms, which are found everywhere in the world in the Karst regions and Slovenia is no exception here. They are from a few centimeters to several meters long karst formations, caused by corrosion along cracks on rock surfaces with less resistance. Usually, their surface is horizontal, but may continue into deep furrows. If karren divide the rock into a chaos of smaller stones, they are also known as “griža” (dysentery).
A similar natural feature, but in smaller dimensions is called flutes.
Karst relief
The karst relief is formed by water which chemically dissolves the limestone and then washes away the rock in the form of a solution. Surface dissolution and lowering of the surface is called karst denudation. It was found that in our climatic conditions denudation is between 20 and 50 m per million years. This means that since Roman times to the present surface in karst regions lowered on average by 2-10 cm.
Water comes to the karst in the form of precipitation and underground streams. Karst streams bring large amounts of water but their effect is limited to the vicinity of the sink. Rainfall is more evenly distributed, but there are still differences in the planar distribution of dissolution, due to different solubility of the rocks and the presence of CO2 in the soil that dissolves in water. Water slowly dissolves the limestone, which under the influence of organic acids in water (they come into it through the atmosphere or by rinsing of soil) is dissolved and mixed with it.
Small karst forms occur on the surface of rocks due to corrosion of water in contact with the rock. On bare rock “škavnice” are formed and in the direction of the slope flutes and larger grooves. At plots with lower corrosion resistance emerge karren, which separate the rock into smaller or larger blocks. Corrosion forms are also formed under the soil. The rock surface is smooth there, formed into soft curves and unusual shapes.
Karren are separated by ridges that in certain places can be extremely sharp. Such ridges are called rock cutters and terrain filled with them is very difficult to pass. Karren may form above ground or underground (if the water formed karren below the top layer of soil).
In the event that karren occur in limestone, covered with soil, which was later removed, their surface is nicely rounded, without sharp edges. It is this very curvature of the surface that is an indicator of how karren were formed. Later, when the soil cover is removed, rain and snow melt the smooth surface but this does not significantly alter the surface curvature.
Karren below Sinji vrh
Karren below Sinji vrh are located at the northern foot of the Sinji vrh peak (1032 m), by the road Col - Predmeja. After the village nearby, Kovk, they are sometimes called “kovške” karren or even karren “na Gori”; Gora is the common name for the territory between Col and Predmeja.
Whatever the name, they are an extremely well developed karren, which occurred in thick strata of Lower Jurassic (Lias) limestone and thus represent a typical example of karst micro relief. So much so they are visited by many school and scientific excursions. They are known by almost all Slovenian naturalists.
There are a lot of different karren and other karst features on Gora, perhaps even more picturesque, but karren below Sinji vrh are located on a very noticeable position and represent a natural monument of national importance. Karren are another unusual phenomenon that speaks of the diversity of nature in Trnovo Plateau. An important scientist, a geologist, once said that if Slovenia didn’t have Trnovo forest, they would have to invent it.
Access
One can get to this EarthCache by taking the road Col – Predmeja. Both are accessible from Ajdovščina, while one can get to Col also from Vipava or from Godovič through Črni vrh nad Idrijo.
Karren are located directly along the road, therefore one must be careful when viewing them. In the immediate vicinity of the EarthCache are two locations where it is possible to park the car on the side of the road (waypoints PARK1 and PARK2).
Access to this EarthCache is possible all year round, because the road is cleaned during winter, but a visit at a time when there’s snow is not reasonable, as karren are then covered and it would be difficult to answer the questions below. In addition, walking on them is also very dangerous when snowy, because the cracks are not visible then. We therefore recommend that you check this EarthCache at a time when there is no snow. Also, always be careful when walking on karren!
EarthCache
To register this EarthCache you must answer the following questions:
1. Take a good look at karren and think about whether they were formed under the soil or on the exposed limestone? Explain your answer.
2. Karren are divided into two well-separated fields. Assess the dimensions of the larger one (the one that is closer to the road).
3. Measure or estimate the depth of the deepest furrows. Is it around 0.3 m, 1.3 m or 2.3 m?
4. Optionally, take a photo of yourself or your GPS at karren and attach it to your log.
Send your answers in Slovene of English through my GC profile. After that you can log your visit, don't wait for permission from me. If there’s something wrong with your answers I will contact you.
If you took photos, attach them to your log.
Logs without the answers sent to me or logs containing the answers will be deleted!
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Viri / Sources:
- Wikipedija
- Društvo Gora
- www.slovenia.info (english)
- Turistično informacijski center Ajdovščina (english)
Slike / Photos (preskoči/skip)
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