(2) The capital of the vilayet, the ancient Castamon, altitude 2 500 ft., situated in the narrow valley of the Geuk Irmak (A mnias), and connected by a carriage road, 54 m., with its port Ineboli on the Black Sea.
The district is watered by the Geuk Su (Calycadnus and its tributaries), and is covered to a large extent by forests, which still, as of old, supply timber to Egypt and Syria.
(2) Axylon, the vast treeless plains on the upper Sangarius; there burst forth at various points great perennial springs, the Sakaria fountains (Strabo p. 543), Ilije Bashi, Bunar Bashi, Geuk Bunar, Uzuk Bashi, &c., which feed the Sangarius.
The most important rivers which flow to the Black Sea are the following: - the Boas (Churuk Su) which rises near Baiburt, and flows out near Batum; the Iris (Yeshil Irmak), with its tributaries the Lycus (Kelkit Irmak), which rises on the Armenian plateau, the Chekerek Irmak, which has its source near Yuzgat, and the Tersakan Su; the Halys (Kizil Irmak) is the longest river in Asia Minor, with its tributaries the Delije Irmak (Cappadox), which flows through the eastern part of Galatia, and the Geuk Irmak, which has its sources in the mountains above Kastamuni.
The Calycadnus (Geuk Su) has two main branches which join near Mut and flow south-east, and enter the sea, a deep rapid river, about 12 m.