Kostelski Buk
Rijeka Una
Glavni izvor rijeke Une nalazi se blizu Donje Suvaje u Hrvatskoj, na sjevernoistočnoj padini planine Stražbenica. To se zove izvor Une a u narodu poznato kao Vrelo Une. 4 km od izvora Una ulazi u Bosnu i Hercegovinu. U tom regionu formira prirodnu granicu prema Hrvatskoj. Una se ulijeva u rijeku Savu blizu Jasenovca, malog sela u Hrvatskoj na samoj granici sa Bosnom i Hercegovinom. Ukupna dužina rijeke iznosi 212 km. Rijeka Una je dobila je ime od jednog Rimljanina koji je prvi i otkrio. On je njenu ljepotu smatrao tako jedinstvenom da ju je prozvao Jedinom (Una).
Tufa i vodopadi
Sadržaj kamenca u vodi Une je izuzetno visok. Tufa (lokalni naziv je Sedra) je raznoliki porozni krečnjak. Nastaje sedimentacijom kalcita u vodi. Ovaj proces stvara barijere i jezerca na rijeci, sto dovodi do stvaranja vodopada. Kod Kostelskog Buka voda pada preko nekoliko kaskada sa visine od oko 10 m i teče dalje oko malih otočića koji se nalaze u sredini rijeke.
Formiranje tufe objašnjeno na Vikipediji
Rastvaranje krečnjaka dešava kroz procesom promjene I uticajem karbonske kiseline. U prirodnom okruženju karbonska kiselina (H2CO3) nastaje rastvaranjem karbon diosksida (CO2) iz vazduha ili iz kišnice (H2O). Krečnjak ili dolomit (CaMg(CO3)2) se sastoji uglavnom od kalcita (CaCO3), koji je teško rastvoriv u vodi. Kalcit se, međutim, rastvara karbosnkom kiselinom, čime se stvara kalcijum hidrogenkarbonat (Ca(HCO3)2). Sve ove hemijske reakcije su prikazane formulama dole:
H2O + CO2 ↔ H2CO3 ↔ H+ + HCO3− ↔ 2 H+ + CO32−
CaCO3 + H2CO3 → Ca(HCO3)2
CaCO3 + H+ + HCO3− ↔ Ca2+ + 2 HCO3− ↔ Ca(HCO3)2
Otok i dječiji zoološki vrt
Gotovo svi odgovori na pitanja o geološkom porijeklu Zemlje mogu se naći na otoku. Da biste došli do otoka, morate proći kroz restoran (što je izričito dopušteno!) i preko drvenog mosta (pogledajte oznake na karti). Na samom otoku ćete naći mnogo različitih formi tufa kao velika stijena, male komade kamena ili kao pijesak. Na otoku se, također, nalazi dječiji zoološki vrt sa kokama, patkama, guskama kozom I magarcem.
Dinosaurus
Izgleda da je prije mnogo vremena također i dinosaurus živio na otoku. Pogledajte putokaz i provjerite oblike u stijenama!
The Cache
Da biste otkrili geološko porijeklo pošaljite odgovore na sljedeća pitanja putem e-mejla na moju geocaching mejl adresu:
1) Pod kojim imenom je još poznat kalcit (hemijski CaCO3)?
2) Dvije stijene: Na karti ćete naći dvije značajne stijene između drveća. Opiši stijene svojim riječima (veličina, boja, struktura, vrsta, …) Kakve specijalne oblike vidite na ovim stijenama?
3) Velika stijena: Na vrhu malog brežuljka ponovno se vidi značajna stijena. Opišite je na isti način kao i prije. Koje specijalne oblike možete ponovno pronaći?
4) Dinosaur: Izgleda kao fosilizirani kostur dinosaura, zar ne? Opišite svojim riječima kako je ovaj kostur stvoren!
5) Izborno: snimite fotografiju od vas i / ili vašeg GPS-a ispred dinosaura.
Napomena: Za prvo pitanje ćete morati pogledati stranicu Vikipedije, a za sve ostale koristite putokaz na otoku.
Kostelski Buk
The river
The river Una has its main source near to Donja Suvaja in Croatia, on the north-eastern slopes of the Stražbenica mountain. This is called the Una spring, also known as Vrelo Une. After 4km the Una enters Bosnia and Herzegovina. There it forms the natural border to Croatia on several longer sections. Una spills into the Sava river near Jasenovac, a small village in Croatia on the border to Bosnia and Herzegovina. The total length of the river is 212km. Una river got its name from Romans who first discovered it. The Romans found its beauty so unique that they named it the One (Una).
Tufa and waterfalls
The lime content in the water of Una is exceptional high. Tufa (the local name is Sedra) is a variety of porous limestone. It is formed by sedimentation of calcite in the water. This process creates barriers and ponds in the river, which leads to the formation of waterfalls. At Kostelski Buk the water falls in several cascades over a height of more than 10m and flows around some small islands located in the middle of the river.
The formation of tufa as it can be found in wikipedia
The dissolution of limestone happens through alteration processes and the effects of carbonic acid. In a natural environment, carbonic acid (H2CO3) is formed by the dissolution of carbon dioxide (CO2) from the air or from rainwater (H2O). Limestone or dolomite (CaMg(CO3)2) mainly consists of calcite (CaCO3), which is not very soluble in water. Calcite, however, is dissolved by carbonic acid, thus creating calcium hydrogencarbonate (Ca(HCO3)2). This is shown by the following formulas:
H2O + CO2 ↔ H2CO3 ↔ H+ + HCO3− ↔ 2 H+ + CO32−
CaCO3 + H2CO3 → Ca(HCO3)2
CaCO3 + H+ + HCO3− ↔ Ca2+ + 2 HCO3− ↔ Ca(HCO3)2
The island and the children's zoo
Almost all answers to log this earthcache can be found on the island. To reach the island, you may walk through the restaurant (this is explicitly allowed!) and over the wooden bridge (see trailhead waypoints). On the island you will find a lot of tufa formations, large rocks, smaller pieces, pepple stones and sand. There is also a children's zoo with hen, ducks, geese, goats and a donkey.
The Dinosaur
Seems that long time ago also a dinosaur was living on the island. Visit the waypoint and take a look at the pattern in the rock!
The cache
To log the earthcache please send the answers to following questions per email to my geocaching account:
1) What other names than calcite do you know for the chemical formula CaCO3?
2) The two rocks: At this waypoint you will find two significant rocks between the trees. Describe the rocks in your own words (size, colour, surface, structure, inclusions, ...). What special objects can you see on these rocks?
3) The big rock: On the top of a small hill you see again a significant rock. Describe it in the same manner as before. What special objects can you find here again?
4) The Dinosaur: It really looks like a fossilized skeleton of a dinosaur, doesn't it? Describe in your own words how this skeleton was created!
5) Optional: Take a photo of you and/or your GPS in front of the dinosaur.
Remark: for answer 1) you might need to ask wikipedia, for all other answers you have to visit the waypoints on the island.
You don't need to wait for my response, you may just log after your visit.
Reference: wikipedia