In the upper sector of the Vulkanland Steiermark, the vineyards on the south-east slope of Joglland near Hartberg are located on crystalline consolidated rocks of the Austroalpine Superunit. These include mainly gneisses and mica-schists and to a lesser degree amphibolites and granites. Farther to the southeast unconsolidated, extremely variable, sandy and abundant gravel rocks of the Styrian Basin are predominant.
The landscape and geology of the lower sector of the Vulkanland Steiermark are shaped by the extinct volcanoes. These features capture the attention of the observer and are unique within Austria's wine regions. However, they form less than ten percent of the parent rocks in the Vulkanland Steiermark. Remnants of an older and a younger volcanic phase include red Trachyandesite, hard black basalt and vesicular basalt scoria. Resulting from explosive volcanic eruptions tuffs formed from solidified ash and fine-grained maar lake deposits. The majority of the vineyards are located on the alternating deposits from the Paratethys Sea, the lakes and rivers of the Styrian Basin and from Quaternary terrace gravels; the majority show a loam cover.
The Sausal with its steep wine growing slopes is composed of phyllitic shales with layers of greenschists and quartzites of the Austroalpine Superunit. On the slopes to the north and at Silberberg, Nestelberg and Rirpenegg one can also find such easily eroded rocks. In addition limestones and clayey-siliceous limestones of Palaeozoic age also occur at Grillkogel.
The majority of the vineyards of Südsteiermark are located upon coarse-grained, gravel river deposits, some of which are consolidated into conglomerates, upon marls, clayey silts and sands of the so-called Styrian Schlier, upon conglomerates and gravels of the Kreuzberg Formation as well as upon sands and marls of the Weissenegg-Formation. These latter units are among the sediments deposited in the Paratethys Sea of the Styrian Basin and date from between about 18 and 15 million years ago. They vary greatly in grain size and calcium content. Pure limestones, similar to the Leitha Limestone, occur locally between Wildon and Gra?nitzberg.
The vineyards are located predominantly on acidic, crystalline consolidated rocks of the Austroalpine Superunit and towards the east are sited on partly coarse and mostly unconsolidated rocks of the Styrian Basin. The so-called Schwanberger boulder debris, with more than one cubic meter sized boulders of crystalline rock, occurs in gullies far into the Koralpe mountain range and underlays vineyards at St. Stefan, Wildbach und Schwanberg. Another formation at the edge of the crystalline area and basins includes river deposits of greenish sands, which merge towards the interior of the basin within the fine-grained, sandy-clayey Florian Beds. They were deposited in the shallow Paratethys Sea about 16 million years ago.
The crystalline consolidated rocks consist of hard, platy gneisses, referred to as Plattengneiss, variable, partly pegmatitic gneisses and dyke rocks as well as garnet mica schists, and to a lesser degree, amphibolites and marble.