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Pamukkale (Cotton Castle), in the west Anatolian sector of the Aegean extensional province, is so named because snow white travertines are accumulating there. Travertine deposition at Pamukkale, one of Turkey's most important tourist destinations, has been in progress for at least the last 400 000 years, and has partially overwhelmed the Roman city and necropolis of Hierapolis. The travertine originates from hot waters that emerge at 35-56°C from open fissures and at least one fault zone. The five principal morphological varieties of travertine mass are: (1) terraced-mound travertines; (2) fissure-ridge travertines; (3) range-front travertines; (4) eroded-sheet travertines; and (5) self-built channel travertines. The first two varieties are similar to those reported from well known travertines at Tivoli, east of Rome, and Mammoth Hot Springs, Wyoming, but the last three varieties have not previously been reported.The orientations of fissure-ridge travertines directly reflect neotectonic directions of stretching that are north-south in the south and north-east-south-west in the north of the Pamukkale plateau. The deposition of about 10 km2 of travertines at Pamukkale is attributed to the presence beneath Pamukkale of carbonate bedrocks and an anastomosing network of fissures intersecting at numerous nodes that provide conduits for the escape of water. These fissures are parallel to the normal faults framing the west-trending Menderes graben and the north-west trending Gediz graben, whose confluence is near Pamukkale.

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Travertine deposits reflect some aspects of the regional tectonics because of the close association between travertine deposits and active fractures, that later of which provide conduits along which travertine-depositing waters may rise. Fissure-ridge travertines form above extensional fissures which are located in the hanging walls of normal faults, in step-over zones between fault segments, or in active (or recently active) volcanic provinces. Numerous active and inactive fissure-ridge travertines are located in the hanging walls of normal faults in the Denizli Basin. A typical fissure-ridge comprises a central fissure along its long axis and flanking bedded travertines dipping away from the fissure. Central fissures of travertine ridges have been dilating since the initiation of the fissures. Samples from both the margins and centres of banded travertine deposits were dated by Th/U methods in order to determine dilation rates. Individual fissures have been dilating at average rates of between 0.008 and 0.1 mm yr -1 during travertine deposition, and ~ 0.001 and 0.007 mm yr -1 after cessation of travertine deposition. There is a noticable decrease in dilation rate from west to east in the Denizli Basin, and this decrease in dilation rate may be related to decrease in overall extension in southwest Turkey, which decreases eastward.

The deformation and 40Ar–39Ar dating of recent volcanism, that remarkably sits across the North Anatolian Fault eastern termination in Turkey, together with previous studies, put strong constraints on the long-term evolution of the fault. We argue that after a first phase of 10 Ma, characterized by a slip rate of about 3 mm/a, and during which most of the trace was established, the slip rate jumped to about 20 mm/a on average over the last 2.5 Ma, without substantial increase of the fault length. The transition correlates with a change in the geometry at the junction with the East Anatolian Fault that makes the extrusion process more efficient.