The Škocjan Caves are
a unique natural phenomenon, the creation of the Reka
River. The Reka River springs from below the Snežnik
plateau and flows some fifty-five kilometres on the
surface. After reaching the Karst, that is the limestone
surface, the river not only deepens its riverbed through
erosion, but also by means of corrosion – it dissolves
the limestone. In the first part of its course on the
limestone, the Reka still flows on the surface, along
an approximately four-kilometre-long gorge that ends
with a magnificent wall under which it disappears underground.
The Reka River blind valley is the largest in Slovenia.
In the distant past, probably in the Early Pleistocene,
that is a few hundred thousand years ago, the ceiling
of the cave collapsed some 200 metres from the sinks;
as a result, the collapse dolines Velika dolina (up
to 165 metres deep) and Mala dolina (120 metres) were
created, separated by a natural bridge, a remnant of
the original cave ceiling. Above the caves, between
the wall above the sink and the walls of Mala dolina,
lies the village of Škocjan. Close to the houses, there
is another entrance to the underground, a ninety-metre-deep
abyss called Okroglica, which ends just above the underground
Reka River.
Cross-section of the Škocjan Caves
At the bottom of Velika dolina, the
Reka River finally disappears underground and resurfaces
again thirty-four kilometres away at the springs of
the Timava River, not far from the Adriatic coast.
Part of the Škocjan Caves in which the Reka River flows,
namely the Šumeča jama (the Murmuring Cave), is only
3.5 kilometres long, between 10 and 60 metres wide
and over 100 metres high underground. The length of
all cave passages totals approximately 6 kilometres,
while the vertical difference between the highest entrance
(Okroglica abyss) and the lowest point in the caves
reached by man, that is the siphon, is 205 metres.
At some places, the gorge extends into underground
chambers. The largest of them, Martel's Chamber, is
308 metres long, 89 metres wide on average (reaching
a maximum of 123 metres) and 106 metres high, with
the highest point of the ceiling at 146 metres above
the Reka River bed (Drole, 1997). The largest cross-section
measures 12,000 square metres, thus giving this chamber
a volume of 2.2 million cubic metres.
