Geosite 1 Nevşehir Castle, Kayaşehir (Rocktown), Oyludağ Basalt and Relief Inversion
Nevşehir Castle is located south of Nevşehir city center. The castle has been used by many civilizations throughout history and has changed hands many times. It is believed to have been built during the Roman period and was also used by the Byzantines, Seljuks, and Ottomans. The castle is on top of a mesa made of Oyludağ basalt, giving it a commanding view of the surrounding area. It was built for defense, and over time, people started living around it.
Kayaşehir is an underground city right below the castle, formed by carving into tuff and ignimbrite rocks. There are many rock-cut spaces here. Around the castle and Kayaşehir, there are many historical and cultural structures that reflect the region's rich history and culture. Archaeological excavations around the castle have found important artifacts from past civilizations.
Oyludağ Basalt consists of black pyroclastics and basalt flows, seen around Kahvecidağ and Göre village, south of Nevşehir. The castle sits on these basalts. The lava flows are 40 meters thick around Kahvecidağ and thin out towards the north, indicating that the source of the lava was near Göre village. The flows extend as far north as Sulusaray. In many places, Oyludağ basalt covers the lake deposits of the Ürgüp formation. The basalts are about 1.9–2.1 million years old and likely flowed northward in an ancient valley, filling it up. Because the surrounding soft rocks eroded away more easily, the basalt flow remained elevated, creating a mesa. Nevşehir Castle is built on this elevated mesa. This shows that around 2 million years ago, the area was much higher than today, and the valley, which was the lowest part, is now higher. This helps us understand how much erosion has occurred in the region over the past 2 million years.