V zgornjem delu doline Kamniške Bistrice, imenovanem Konec, je tik ob cesti proti spodnji postaji tovorne žičnice k Cojzovi koči na Kokrškem sedlu velik ledeniški balvan v obliki kvadra, ki pozornost pritegne s svojimi pravilno oblikovanimi, ravnimi stranicami. Še večje presenečenje nas čaka, če si ga ogledamo od strani, saj je v podolžni smeri (v smeri vzhod–zahod) po celotni dolžini preklan na dvoje, kot bi ga nekdo prežagal. Od tod tudi njeno ime - Žagana peč.
Skalnati samotar, na katerem je zapisana nadmorska višina 808 m, ima od 7 do 10 metrov visoke navpične stene in od 15 do 20 metrov dolge stranice. S tako pravilnimi linijami na tem mestu ne bi mogel nastati kot posledica skalnega odloma ali podora, saj bi se ob padcu zagotovo raztreščil na manjše kose. Zato gre za zajetno kamnito gmoto, ki se je v zadnji, würmski poledenitvi odlomila od živoskalne osnove, zdrsnila na ledenik in v njem popotovala po dolini navzdol. Ob tem se je dodatno obrusila. Ko se je led stalil, je na ledeniški moreni nasedla. Sprva balvan še ni bila razklan, ker pa podlaga pod njim ni bila ne ravna ne enako trdna, se je ob leziki preklal na neenako velika dela, pri čemer se je manjši del mestoma posedel za pol metra. Povsem ravna in navpična prepoka, ki razdvaja Žagano peč, je široka od 20-30 cm in je zapolnjena s posameznimi zagozdenimi večjimi in manjšimi kamni.
Balvan še zdaleč ni povsem kompaktna skala, saj pogled od blizu razkrije prepletanje večjih in manjših razpok, ravnih, poševnih in celo ukrivljenih kamninskih skladov ter bolj trdnih delov. Zaradi preperevanja se je ponekod del sten že odkrušil, na vrhu pa je nastal tenek, z mahom prekrit sloj prsti, iz katerega so pognale kar zajetne smreke. Med strmimi obodnimi stranicami je še najbolj obrušena južna. Tamkajšnja povsem navpična stena je vzporedna s prepoko in tako slabo razčlenjena, da jo alpinisti uporabljajo kot odličen plezalni vrtec, zato je v njej zabitih nekaj klinov, namenjenih varovanju.
Ledenik je v dolini pustil še več velikih skalnih samotarjev, ki jim zaradi nastanka pravimo tudi ledeniški balvani. Največji med njimi je Sivnica, eden največjih balvanov na jugovzhodnem obrobju Alp. Skala je kar štirinajskrat večja od Žagane peči. Velik je tudi Lepi kamen, na katerem je celo lovska koča. Sicer pa je v okolici raztresenih večje število balvanov vseh velikosti, celo na izviru reke Kamniške Bistrice jih najdemo.
Slika: Primerjava velikosti največjih balvanov v Kamniški Bistrici
Balvani so nastali, ko so se ledniki premikali po površju zemlje in s seboj prenašali velike količine skalnega materiala. Proces nastajanja ledeniških balvanov se začne z delovanjem lednika, ki se premika in pod svojo težo zdrobi in odtrga kamne ter skale s tal. Te skalne fragmente, ki se imenujejo ledeniški sedimenti, lednik prenaša in premika po površju. Ko se lednik umakne, balvani ostanejo na mestu, kjer so se odlagali, in tvorijo značilne ledeniške morene ali ledeniške kraške vrtače.
Okoli 8 kilometrov dolg ledenik je segal vse do Kraljevega hriba in izteka doline Korošice. Za seboj je pustil obsežne čelnomorenske nasipe ter številne balvane. Ledenik se je napajal iz širšega območja med Planjavo, Ojstrico in Lučkim Dedcem, od koder je led pritekal po dolini Kamniške Bele. Drugo večje redišče ledu je bilo med Brano, Skuto in Grintovcem, od koder je led v obliki ledenih plazov in serakov padal preko strme stopnje v glavno dolino. Obsežen ledeniški plato, ki je napajal Bistriški ledenik, se je nahajal tudi med Kalško goro, Kalškim grebenom in Jermanovim vrhom. Manjši ledenik je pritekal tudi iz smeri Kamniškega sedla in drugih manjših dolin, o čemur pričajo številne krnice na grebenih
Slika: Sledovi poledenitve v dolini Kamniške Bistrice
Vir/Source:
Wikipedija
GeograFF 22
Kamniška Bistrica – geografska podoba gorske doline
Avtorji: Nejc Bobovnik, Dejan Cigale, Tanja Koželj, Karel Natek, Darko Ogrin, Matej Ogrin,
Dušan Prašnikar, Blaž Repe, Uroš Stepišnik, Tajan Trobec, Miroslav Vysoudil
Urednik: Darko Ogrin
Recenzenta: Metka Špes, Dušan Plut
Kartografi: Nejc Bobovnik, Dejan Cigale,Tanja Koželj, Blaž Repe, Uroš Stepišnik, Tajan
Trobec Fotografi: Dejan Cigale, Žiga Jamnik, Karel Natek, Darko Ogrin, Dušan Prašnikar, Blaž
Repe, Uroš Stepišnik, Tajan Trobec, Miroslav Vysoudil (termalne slike)
NALOGE ZA VPIS:
Obiščite naslednje tri točke in odgovorite na vprašanja:
ŽAGANA PEČ: N46° 20.270 E014°34 285
A) Kaj misliš, ali se bo Žagana peč lahko še dodatno razklala, ali se bo prevrnila, ali nanjo delujejo kakšni naravni vplivi...
Odgovor A=
______________________________
B) Kaj so balvani? Opiši nastanek in izgled balvana na tem mestu.
Odgovor B=
______________________________
LEPI KAMEN: N46° 20.476 E014°34 398
SIVNICA: N46° 20.402 E014°34 499
C) Primerjaj kaj imajo skupnega Žagana peč, Lepi kamen in Sivnica ter v čem je bistvena razlika?
Odgovor C=
Pred vpisom zemeljskega zaklada, pošljite odgovore preko GC profila. Za vpis ne potrebujete dodatnega dovoljenja. V primeru, da bo kaj narobe z odgovori vam bom odgovoril.
- Vpisi brez ustrezne spremljajoce e-pošte, ki vsebuje pravilne odgovore, bodo najprej trajno kodirani, kasneje izbrisani!
- Vpisi, ki vsebujejo odgovore bodo izbrisani!
- Dobrodošle so fotografije Žagane peči, Lepega Kamna ali Sivnice na kateri ste tudi vi (ni potrebno, da je viden obraz) ali listek z vašim geo vzdevkom ali vaš gps ali kaka geo igrača.
In the upper part of the Kamniška Bistrica valley, called "Konec", right by the road leading to the lower station of the cargo cableway to Cojz's hut at Kokrško saddle, there's a large glacial boulder shaped like a cuboid, catching attention with its regularly shaped, straight sides. An even bigger surprise awaits when viewed from the side, as it is split in half longitudinally (east-west direction) for its entire length, as if someone sawed through it. Hence its name - "Žagana peč" or "Sawn Rock".
This rocky solitary, marked with an altitude of 808 m, has 7 to 10 meters high vertical walls and 15 to 20 meters long sides. With such regular lines, it couldn't have naturally formed here as a result of a rock break or landslide, as it would have surely shattered into smaller pieces upon falling. Thus, it's a massive stone mass that broke off from the bedrock during the last, Würm glaciation, slid onto the glacier, and traveled down the valley within it. Along the way, it got further refined. As the ice melted, it landed on the glacial moraine. Initially, the boulder wasn't split, but since the ground beneath it wasn't flat or evenly firm, it split into uneven parts, with the smaller part settling in places by half a meter. The completely straight and vertical crack separating "Žagana peč" is 20-30 cm wide and filled with wedged larger and smaller stones.
The boulder is far from a solid rock, as a closer look reveals a mixture of larger and smaller cracks, flat, slanted, and even curved rock layers, and more solid parts. Due to weathering, parts of the walls have chipped off, and a thin layer of soil covered with moss has formed on top, from which quite large spruces have sprouted. Among the steep peripheral walls, the southern one is the most refined. The completely vertical wall there is parallel to the crack and so poorly articulated that mountaineers use it as an excellent climbing garden, hence some pegs intended for protection are hammered into it.
The glacier left several large solitary rocks in the valley, which are also called glacial boulders due to their origin. The largest among them is Sivnica, one of the largest boulders on the southeastern edge of the Alps. The rock is fourteen times larger than the Žagana peč. The Lepi kamen (Beautiful Stone) is also large, with a hunting lodge on it. Otherwise, there are a number of boulders of all sizes scattered around the area, even at the source of the Kamniška Bistrica river, they can be found.
Boulders are formed when glaciers move across the earth's surface, carrying large amounts of rock material with them. The process of forming glacial boulders begins with the action of the glacier, which moves and, under its weight, crushes and tears rocks and stones from the ground. These rock fragments, called glacial sediments, are transported and moved by the glacier. As the glacier recedes, the boulders remain in the place where they were deposited, forming typical glacial moraines or glacial karst depressions.
A glacier, about 8 kilometers long, extended all the way to Kraljevi hrib (King's Hill) and the outlet of the Korošica valley. It left behind extensive frontal moraine mounds and numerous boulders. The glacier was fed from a broader area between Planjava, Ojstrica, and Lučki Dedec, from where the ice flowed through the Kamniška Bela valley. Another significant reservoir of ice was located between Brana, Skuta, and Grintovec, from where ice, in the form of ice avalanches and seracs, fell over a steep stage into the main valley. An extensive glacial plateau that fed the Bistrica glacier was also located between Kalška gora, Kalški greben, and Jermanova peak. A smaller glacier also flowed from the direction of Kamniško sedlo and other smaller valleys, evidenced by numerous cirques on the ridges.
TASKS:
Visit the following three points and answer the questions:
ŽAGANA PEČ: N46° 20.270 E014°34 285
A) Do you think Žagana peč might further split, topple over, or if there are any natural forces acting on it...
Answer A=
______________________________
B) What are boulders? Describe the formation and appearance of the boulder at this location.
Answer B=
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LEPI KAMEN: N46° 20.476 E014°34 398
SIVNICA: N46° 20.402 E014°34 499
C) Compare what Žagana peč, Lepi kamen, and Sivnica have in common and what is the main difference?
Answer C=
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