Lookout tower - Sphinx in Boldogkőváralja

The castle is built on a huge and unique rocky ridge, which in some views looks exactly like a Sphinx. The Zemplén Mountains were built up by millions of years of intermittent volcanism. In the western parts of the mountain range, there were several large eruption centres. In the areas around Boldogkőváralja, there are large thicknesses of chemically acid rhyolite tuff from volcanic explosions. It occurs also in the form of so-called dust tuff falling back from the atmosphere, as well as ignimbrite avalanching down the side of the volcano. The Castle Hill and its surroundings are mainly built up by such ignimbrite with high pumice content. It is clearly observable on the rock ridge of the castle that the rock mass there, which is oriented close to the north-south direction, is much more resistant than its surroundings, as it has not decayed as quickly as the surrounding tuffs. The reason for this is that, after the volcanic activity, the pumice rhyolite tuffs of the near north-south oriented caldera ridge have cakes, that is, become ignimbrites. This caking process has made the mountain material extremely resistant and, therefore, it has better resisted to erosion. A darker coloured weathering crust is clearly visible on the tuff.