|Location:||Zgornja Idrijca Natural Park|
|Dimension:||VR=200m, A=1,100m asl.|
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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Smrekova draga (Spruce Glen) is a huge doline with 200m high walls. The huge bowl has a volume of 18Mm³ which makes it the biggest doline in Slovenia. However, it is not exactly a doline, as it was formed as a glaciokarstic depression, not as a collapse doline. It was formed at least partly by the forces of the glaciers during the Ice Age. As a result the slopes are not very steep. The name of such a kind of doline in Slovene karst terminology it is a konta.
The ground of the sinkhole is very cold from cold air coming out of the ground. A cave below is connected with an entrance high up in the mountains, and the cold air is trapped by the cave and flows out during the year on the ground of this doline.
The result of this ground cooling is an inversion of vegetation zones. While in the mountains normally temperatures decrease with height, in this case the temperature increase with height. As a result the vegetation zones are inverse, the coldeast at the bottome and the warmest at the top. But thats not all, as soon as one leaves the doline anything is as usual again. Vegetation zones now become again colder when continuing the ascend. The result is a sort of mirror effect.
The forest road is runing along one side of the doline and it is very good visible. The whole area is protected, especially the vegetation, so it is not allowed to leave the trails. Please enter the doline only with a guide. If you are on your own, bring a good binocular and you will be able to see anything from the road.