Fig. 12.1. Main regions of Hungary

Hungary has a great diversity of rocks. The oldest surface rocks can be found in the Zemplén Mountains (about 900 million years old), but there are parts under the surface which were are dating back 1.1 billion years ago. The most important mountains made of granite were formed in the Carboniferous period of the Earth’s history. These are the Velence Mountains and the Mórágy Block. Moreover there are granite stripes under the Great Hungarian Plate. In the Triassic period mainly mountains composed of limestone were formed. We can see large limestone and dolomite surfaces in the Transdanubian Mountains (for example Vértes, Pilis, Buda Mountains), parts of the Mecsek, the Villány Mountains and the Bükk Mountains. Limestone of economic importance can be found in the Bakony Mountains and in the Gerecse Mountains. It was deposited in the Jurassic period. There is a volcanic chain under the sediment of the Great Hungarian Plate, which is the remain of strong geological activities in the area during the formation of the European members of the Eurasian Mountain System. These volcanoes are about 130 million years old. During the Miocene period the mountains of the Carpathians were rising, while the Carpathian Basin was sinking. On the margin of these two different regions, strong volcanic activity began, which resulted in the formation of a ring of volcanoes in the Carpathian, stretching from the Visegrád Mountains to Hargita (Transylvania). The post-volcanic activities of this period caused the hydrothermal ore-production (copper, led, zinc) of the Börzsöny, Mátra and Zemplén Mountains (Fig. 12.2.).