In Cappadocia, in an area of approximately 30 by 20 kilometres (the triangle of Nevşehir-Avanos-Urgüp triangle) there are marvellous tuff rocks of the most bizarre shapes. The reason is that they are the result of the eruption of the Erciyas volcano, which happened a long time ago. Flows of lava mixed with ash poured down into the the valley of Gereme and thickly covered an area of several thousand square kilometres. kilometres. Then, over the centuries, the winds blew away, the rains washed away the lighter rocks and the and the solidified lava and compacted ash gradually turned into tuff - a soft to work and yet durable building material. soft to work yet durable building material.
There are about 400 churches in the neighbourhood of Guereme. Some were built by early Christians from the time of Basil the Great (century), but most of them dates from the 9th to 11th centuries, the period of iconoclasm and Seljuk rule. The latest church was built shortly before the Mongol invasion in the 13th century.
The most famous are: the 11th-century church of St Basil with many frescoes; the church of St Barbara, decorated with frescoes; and the church of St Basil, decorated with frescoes. St Barbara's Church, decorated with geometric patterns of red ochre; the Church of the Sandals, so called because of its frescoes. Sandals, so named after the two depressions on the floor at the entrance, with preserved XI century frescoes; the Serpent Church with frescoes depicting St George with the dragon, Emperor Constantine and his wife Helen, St Onuphrius; the Curved Church is one of the largest churches with 10th-century frescoes depicting scenes from the life of Christ.
