Matjaževa jama leži nad vasjo Zavrh pod Šmarno goro v severnem delu slovenskega krasa. Jama je dolga le nekaj deset metrov in ima eno glavno kupolasto dvorano z nižjim stranskim nadaljevanjem ter izrazitim stropnim oknom. Čeprav je razmeroma majhna, omogoča lep vpogled v to, kako apnenčasta podlaga reagira na delovanje vode in kako se začnejo razvijati kraški procesi.
Matjaž Cave lies above the village Zavrh pod Šmarno goro, in the northern part of the Slovenian karst region. The cave is only a few dozen metres long and consists of a single main dome-shaped chamber with a lower side passage and a distinctive ceiling window. Although relatively small, it offers an excellent opportunity to observe how limestone bedrock responds to the action of water and how karst processes begin to develop.
Geološka značilnosti
Jama je razvita v razmeroma čistih, dobro topnih apnencih, ki po Geološki karti Slovenije spadajo v enoto K1,2, sestavljeno iz lapornate gline, plastovitega apnenca in apnenčeve breče mezozojske starosti. Šmarna gora predstavlja majhen izoliran blok teh apnencev – »apnenčasti otok«, obdan z nekraškimi kamninami, kot so skrilavci. V glavni dvorani so jasno vidne tanke plasti apnenca ter kontrastna obarvanost sten od svetlo sive do rjavooranžne, ki je posledica prisotnosti železa in mangana v kamnini ter pronikajoči vodi.
Geological characteristics
The cave has developed in relatively pure, well-soluble limestones which, according to the Geological Map of Slovenia, belong to unit K1,2, composed of marly clay, bedded limestone, and limestone breccia of Mesozoic age. Šmarna Gora represents a small isolated block of these limestones – "limestone island" surrounded by non-karst rocks such as shale. In the main chamber, thin limestone bedding is clearly visible, together with contrasting wall coloration ranging from light grey to brownish orange, caused by the presence of iron and manganese in both the rock and percolating water.
Geološka karta okolice Matjaževe jame
(vir: EGeologija 2026, lastna prilagoditev)
Stropno okno in razvoj jame
Najizrazitejši element Matjaževe jame je naravno stropno okno, ki povezuje glavno dvorano s površjem ter omogoča vdor dnevne svetlobe in padavinske vode. Okno je nastalo vzdolž strme navpične razpoke nad zgornjim delom jame, kjer je dolgotrajno raztapljanje apnenca z vodo, bogato z raztopljenim CO₂, v kombinaciji s površinskim preperevanjem postopoma tanjšalo in oslabljalo skalni strop. Ko je nadložna kamnina postala dovolj oslabljena, se je del stropa porušil in vzpostavil neposredno povezavo s površjem. Danes okno predstavlja končno fazo razvoja navpične razpoklinsko pogojene jame.
Ceiling window and cave development
The most distinctive feature of Matjaževa jama is a natural ceiling window that connects the main chamber to the surface, allowing daylight and precipitation to enter. The window formed along a steep vertical fracture above the upper part of the cave, where long-term dissolution of limestone by CO₂ rich water, combined with surface weathering, gradually thinned and weakened the rock ceiling. Once the overlying rock mass became sufficiently weakened, part of the ceiling collapsed, creating a direct connection to the surface. Today, the window represents the final stage in the development of a vertically fracture-controlled cave.
Nastanek stropnega okna v jami
(skica: L. Mertely)
Kraški pojavi
Na stenah Matjaževe jame so jasno vidni zgodnji kraški pojavi: tanke sige (tokovni kalcitni premazi), zavesaste tvorbe ter drobni kalcitni robovi, ki nastajajo zaradi dolgotrajnega pretakanja vode, nasičene s kalcijevim hidrogenkarbonatom, Ca(HCO₃)₂, po površini kamnine.
Ob prezračevanju ali segrevanju jamskega zraka se ogljikov dioksid izloča, ravnotežje reakcije
CaCO₃ + CO₂ + H₂O ⇌ Ca(HCO₃)₂
pa se pomakne v levo. Iz raztopine se zato ponovno izloča trdni kalcit (CaCO₃), ki tvori skorje, robove in drobne sige.
Rjavkasto-oranžni premazi kažejo na prisotnost železovih in manganovih oksidov v raztopini, medtem ko svetlo sivi do beli pasovi predstavljajo skoraj čist kalcit. Barvne razlike tako odražajo spremembe v kemični sestavi vode v različnih obdobjih. Na mestih intenzivnejšega odtekanja so nastale tudi majhne kotanjice in žlebovi – korozijske oblike, ki nastajajo tam, kjer voda z raztopljenim CO₂ dolgotrajno raztaplja apnenec.
Diagram procesa kraščenja apnenca
Karst features
The walls of Matjaž Cave clearly show early-stage speleothems: thin flowstone coatings, curtain-like formations, and small calcite ridges formed by the long-term flow of water saturated with calcium bicarbonate, Ca(HCO₃)₂, over the rock surface.
When the cave air is ventilated or warms up, carbon dioxide escapes and the equilibrium of the reaction
CaCO₃ + CO₂ + H₂O ⇌ Ca(HCO₃)₂
shifts to the left. As a result, solid calcite (CaCO₃) precipitates from solution, forming crusts, ledges, and small flowstone deposits.
Brownish-orange coatings indicate the presence of iron and manganese oxides in the solution, whereas light grey to white bands represent nearly pure calcite. The colour variations therefore reflect differences in the chemical composition of the water at different times. In areas of more intensive runoff, small basins and grooves have formed – corrosion features created where water enriched in dissolved CO₂ continuously dissolves the limestone.
In zdaj k temu, kaj morate storiti, da boste uspešno zabeležili ta cache... Vaša naloga je, da odgovorite na spodnja vprašanja in mi odgovore pošljete na e-poštni naslov - geovasek01@gmail.com. V zadevo sporočila napišite "Matjaževa jama" in v besedilu ne pozabite navesti svojega vzdevka. Če bo kaj nejasno, vas bom kontaktiral. Najdbo lahko zabeležite takoj po tem, ko pošljete odgovore.
Vaše naloge
1) Po čem je Matjaževa jama edinstvena?
2) Opišite, kako je nastalo stropno okno v jami.
3) Na stenah jame poiščite kraške pojave. Kakšnih barv so in kaj pomenijo te barvne razlike?
4) Na vhodu v jamo posnemite fotografijo sebe ali svojega osebnega predmeta in jo priložite k logu!
And now to what you need to do to successfully log this cache... Your task will be to answer the tasks below and send me the answers to my email - geovasek01@gmail.com. Please write "Matjaževa jama" in the subject line and don't forget to include your nickname in the message. If there is any confusion, I will get back to you. You can log in as soon as you receive the answers.
Your tasks
1) What makes Matjaževa jama unique?
2) Describe how the ceiling window in the cave was formed.
3) Identify karst features on the cave walls. What colors do they have, and what do these color differences indicate?
4) Take a photo of yourself or your personal item at the cave entrance and attach it to the log!
Upam, da boste uživali v earthcache izkušnji. Če imate še kakšne fotografije območja, bodo seveda zelo dobrodošle. Želim vam uspešen lov in vesel bom tudi kakšne točke priljubljenosti.
Viri
BLATNIK, M. et al. (2020): Karstology in the classical karst. Springer Nature.
EGEOLOGIJA (2026): Osnovna geološka karta 1:100 000. Dostopno TUKAJ (pridobljeno 28. 2. 2026).
KATASTER JAM (2026): Matjaževa jama. Dostopno TUKAJ (pridobljeno 28. 2. 2026).
MIHEVC, A. et al. (2016): Karst in Slovenia. Boletín Geológico y Minero, 127(1), 79-97.
UNESCO (2025): Classical Karst. Dostopno TUKAJ (pridobljeno 28. 2. 2026).
Photos by Václav Jícha & internet