A striking rock formation watches over the valley of the Bílina River near a town of the same name. To the locals, its characteristic silhouette is reminiscent of a resting lion. The crag that bears the name Bořeň is, as the vast majority of the České středohoří Mts, of volcanic origin. Volcanic activity in the České středohoří Mts lasted for a relatively long period of time. It began roughly 35 million years ago, culminated about 30 million ago, and nearly ceased some 20 million years ago. However, a group of small volcanic cones was active as late as 10 million years ago. Bořeň Hill itself was formed during the period of the most intensive activity dating back about 30 million years. At that time, near the cities of Bílina and Most, massive effusions of basaltic lava were followed by eruptions of phonolite volcanoes.
The brochure Bořeň introduces to the stages of the creation, but it also contains pictures with AUGMENTED REALITY!Photoa are displayed by application named Geology AR, which can be downloaded for free from Google Play to your smartphone or tablet.