For the tourist, the attraction of this area is underground: a variety of huge subterranean caves gouged in the soft limestone by deep rivers boasting stalagmites, stalactites, and other surprising formations that inspired the celebrated British sculptor Henry Moore to write in the visitor's book of the Postojna Caves "This is the best exhibition of Nature's sculpture I have ever seen."
The karst surface of the Kras area seems quite inhospitable: clean white limestone rocks can be seen everywhere, with vegetation struggling for survival. The soil of this area is terra rossa, the characteristic red earth that is a product of limestone decay - in geological terms, brand new. On exposed sites, the layer of soil is very thin, but it does collect in the characteristic karst valleys or vrtace. The soil has a high content of aluminum oxide, and the characteristic red colour comes from its high content of iron oxides (hematite).
The climate is harsh: scorching summers with frequent lasting droughts and cold winters aggravated by the burja which dries the land. Rainfall is not slight, but rains tend to come in late spring during the grapevine's flowering season and in the autumn when the grapes are maturing. Rainwater quickly disappears in the porous bedrock.
Some 560 hectares (1384 acres) of Kras vineyards are situated on flat terrain or very lightly inclined slopes: on more variegated relief, the layer of soil is too thin. The vineyards are carefully weeded to save all the nutrients and water for the vine; the grapevine is grown (or "trained," the term that experts use to denote the initial shaping of a grapevine) in the form of an arbour (with supporting latticework) so the leaves create shade to protect the soil from the desiccating rays of the sun. This makes harvest work exceedingly hard and tiring since all the grapes must be cut with harvester's hands above his head.
The characteristic wine of the Kras area is Teran, a vigorous wine rich in colour and aroma. Teran differs from site to site, with the northern varieties being richer in alcohol and lower in acids. It is widely believed that Teran has medicinal properties, some confirmed by modern medicine. In the past, it was sold in pharmacies, and for old times sake special small "apothecary" bottles of Kraski Teran are still on sale today.
The western edge of the Kras area bordering on the Koper area has a more submediterranean climate, and the soils are less pure terra rossa. These sites produce gentler wines such as Refosk, a rich and aromatic Malvazija, and Prosecco.
The characteristic blends of the area are Krasko rdece, a dry red wine blended from Refosk and Merlot, and the white Krasko belo, a blend of Rebula and Laski Rizling. Tasted young, straight from the barrel, this wine is extremely attractive and quite noble.
The largest wine cellar of the Kras area is in Sezana where the cellarers have mastered the aging of Kraski Teran. This is where the smooth Teranton comes from, its best vintages being 1979, 1985, 1986, and 1989.
