Suk Mountain, better known under the local name Sopka (Volcano), is located to the west of Karlovy Vary above the village of Hory, with is summit at an elevation of 579 metres. The mountain is of volcanic origin and it was formed in the Tertiary period when volcanoes had been active in the Doupov area. It is also the period during which a marked fault in the earth's crust known as the Chodov Fault had been created along with a separate volcanic funnel that later gave birth to the present-day mountain. The shape and the composition (olivine nephelinite) of the mountain distinctly distinguish it from the surrounding terrain and they are also the reason for its peculiar name, i.e. Suk (literally meaning "Knot"). Geologists initially attributed major significance to the volcano in connection with the formation of the Carlsbad thermal springs. The volcano and its geological structure were also explored by J. W. Goethe during his stay in Karlovy Vary (Carlsbad) in 1820.
Direct evidence of past volcanic activity is basalt, an eruptive rock visible in the excavated parts of the western slope on the site of the deserted quarry. The quarry wall uncovered impressive specimens of basalt columnar jointing. Hyalite (water opal) may be found at rare occasions in the form of thin layers on basalt rock. From the early 19th century, basalt was quarried on the volcano for road building purposes. In the 1970’s, it was one of the largest quarries of the West Bohemian Region. Mining activities were discontinued several years ago due to the immense devastation of the mountain and the only relics are what used to be, feed hoppers for extracted stones.
The extensive basalt massif has never been continuously covered with forest stands. We may only find groups of trees and bushes or solitary specimens of woody plants commonly found in the area. Several old specimens of the hedge maple (Acer campestre) are worth mentioning. The meadow below the southeastern slope of the mountain is planted with European mountain ash (Sorbus aucuparia var. moravica). The basalt sub-grade promotes the occurrence of a large number of thermophilic plant species, such as the crown vetch (Securigera varia), mountain clover (Trifolium montamun), basil thyme (Calamintha acinos), stemless thistle (Cirsium acaule), agrimony (Agrimonia eupatoria), swallow wort (Vincetoxicum hirundinaria) and tor grass (Brachypodium pinnatum). Other species that are not as common in the region, yet are indeed worth mentioning include, for example, the five-faced bishop (Adoxa moschatellina), and corydalis (Corydalis intermedia) frequent in shades under bushes, or the yellow anemone (Anemone ranunculoides) and pale St. John's wort (Hypericum montanum) inhabiting grassy slopes and meadows.