Downloaded from http://sp.lyellcollection.org/ by guest on September 25, 2021 Creation and destruction of travertine monumental stone by earthquake faulting at Hierapolis, Turkey P. L. HANCOCK *'1, R. M. L. CHALMERS 1, E. ALTUNEL 2, Z. ~AKIR 3 & A. BECHER-HANCOCK 4 1Department of Geology, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1R J, UK 2 Jeoloji Mt)'hendisligi B6lffmff, Miihendislik Mimarlik Fakiiltesi, Osmangazi University, Eskisehir, Turkey 3 Engineering Faculty, Mersin University, Ciftlik Koyu, Mersin, Turkey 4 Department of English, University of Bristol, 3-5 Woodland Road, Bristol BS8 1TB, UK Abstract: The presence of travertines adjacent to the city and their value for construction was well known to the Greek, Roman and Byzantine residents of Hierapolis (modern Pamukkale). The travertines were mainly extracted from quarries on the outer slopes of a low plateau below the city. The distinctive attribute of most of the quarries is that they are narrow but deep vertical-sided trenches. Each trench is the site of a nearly vertical fissure that was filled by banded fissure travertine, one type of so-called Phrygian marble. Trench walls, formerly the contacts between vertical banded travertines and outward dipping bedded travertines, bear a well-defined herringbone pattern of tool marks identical to those on many of the stone blocks that were used for building Hierapolis. Deposition of the travertines in 21 major fissure-ridges was a consequence of precipitation following degassing of carbonate-rich hot waters emerging from springs aligned along active faults and associated fissures. Whereas the dense and attractively banded travertine in fissures was principally used as an ornamental stone, the bedded travertines of ridge sides were mainly employed as a dimension stone and for making columns. After many of the monuments at Hierapolis had been constructed from travertine, itself a faulting-related material, some of them were subsequently destroyed or damaged by earthquake fault reactivation, which caused them to be either shaken or displaced. The zone of greatest seismic damage coincides with the trace of the Hierapolis fault zone, whose location was detected from an alignment of offsets of walls and petrified irrigation channels. The kinematic class of this fault zone could be deduced because offsets of the linear archaeological features permitted opening directions to be determined, thus allowing the fault zone to be reinterpreted as a normal fault zone achieving a small downthrow to the southwest. The knowledge that the Hierapolis fault zone is a structure across which there is active stretching and increased hydrothermal flow helps to explain why the present-day area of hot pools and travertine deposition is situated immediately downslope of the fault trace. If this relationship between displaced features and recent travertine deposits occurs elsewhere it might be employed for finding the locations of earthquake faults. The purpose of this paper is to explain how Greek and Roman cities in the Maeander River earthquake faulting in the city of Hierapolis is valley (the present Menderes River) (Fig. 1), is associated with the deposition of a large body of roughly coincident with the present tourist travertine that was quarried for stone in Greek village of Pamukkale, a settlement that in the and Roman times, and how subsequent reacti- last 50 years has served the needs of visitors not vation of faults in the same area during these only to Hierapolis but also to the famous white periods and later was responsible for damaging travertine deposits that give Pamukkale its the city. The site of Hierapolis, one of several name, 'cotton castle'. Excluding the extensive northern necropolis and smaller southern necro- *Deceased, reprint requests should be addressed to polis, much of Hierapolis lies within its late A. Becher-Hancock. Roman city wall (Peres 1987) (Fig. 2). From: McGUIRE, W. G., GRIFFITHS, D. R., HANCOCK, P. L. & STEWART, I. S. (eds) The Archaeology of Geological Catastrophes. Geological Society, London, Special Publications, 171, 1 14. 1-86239-062-2/00/$15.00 © The Geological Society of London 2000. Downloaded from http://sp.lyellcollection.org/ by guest on September 25, 2021 I J 27 ° 31 ° (a) Black Sea TRIPOLIS j-w-- . River o Sarayk6y HIERAPOLIS Gediz graben / .PamukkalE . / EXTENSIONAL I,o 0raVen :DENIZLI BASIN ~h, ~. I i ~ , , ! ,~ .~...q.".Denizli | 100 Km Mediterranean kilometres ~'~.ZCZCZ."...~'II!~'~-{:'.I~.":":" COLOSSAE L I Pre-Neogene ~ Neogene r-~ Quaternary travertine active normal fault ticks on downthrow side Fig. 1. (a) Turkish sector of the Aegean extensional province. (b) Geological, topographic and historical setting of Hierapolis within the Denizli basin (modified after Altunel & Hancock 1993a). Downloaded from http://sp.lyellcollection.org/ by guest on September 25, 2021 CREATION AND DESTRUCTION OF TRAVERTINE MONUMENTAL STONE 3 Hellenistic theatre Northern bath~ ~) Martyrionof gatewayMonumental(Frontinus) ~,:" ~ / Northern-'~" city gate ~ St Philip Nl J .... _ ____.._ .. Colonnaded street ~X~ Temple of NkI City wall Apollo \~ gendarme post % ~) RomanI theatre Southern baths Sacred pool ' I Byzantine fort Hierapolis fault ,,~ zone 0 500 ~..~ " I I Southern city gate metres Fig. 2. Sketch map of selected principal monuments within Hierapolis. Neotectonic, topographic and trend NW SE, that is, they follow the Gediz gra- historical setting ben trend. The Denizli basin and the Gediz graben are separated by a zone, to the northwest Many landforms in regions of active extensional of Buldan (Fig. lb), that does not contain large tectonics directly reflect recent earth movements normal faults and hence is not expressed by a and hence they can have a great influence on graben or basin. routeways and settlements. This is especially The floor of the Denizli basin is mainly true of western Anatolia, which is situated in underlain by Neogene and Quaternary clastic the east of the Aegean extensional province sediments. The Quaternary travertine masses of (Fig. la), a region currently experiencing nor- the basin, of which the Pamukkale mass is only mal faulting and the formation of rift valleys one, rest on these clastic sediments. External to (grabens) and intervening horst-block moun- the Denizli basin there are outcrops of meta- tains as a consequence of roughly NNE-SSW morphic and igneous basement rocks uncon- stretching (Jackson 1994). formably overlain by Neogene clastic deposits. Hierapolis is sited on the northeastern edge of The Pamukkale range-front fault separates the the Denizli basin, a structure within the Men- sediments of the Denizli basin from the base- deres graben but close to its confluence with the ment rocks to the northeast, with a down- Gediz graben. The Denizli basin has been throw southwest of at least 450m (Altunel & subsiding since Miocene time (Westaway 1993). Hancock 1993a). It is framed to the south by a major E-W trend- The large-scale topography of the region is a ing normal fault, which is part of the Menderes direct expression of Neogene and Quaternary system, but to the northeast the principal faults tectonic activity. For example, the Denizli basin Downloaded from http://sp.lyellcollection.org/ by guest on September 25, 2021 4 P.L. HANCOCK ET AL. is an area of low relief, the nearly level Quat- 2300 m and the even higher peak of Honazdag, ernary flood plains of the Maeander and Lykus south of Colossae, achieves 2571 m. Between the (modern ~uruksu) rivers being at about 280m Denizli basin and the Alasehir valley of the above sea level and about 60 m lower than the Gediz graben is an area of high but not rugged surrounding incised plateau underlain by Neo- ground, rising to about 1324 m. gene sediments. The mountain massif of K~gfik The Pamukkale travertines, which were used ~6kelezdag to the northeast of the basin rises to for building Hierapolis, are situated within what a maximum of 1739m, whereas to the south of we call the Pamukkale plateau but some parts Denizli the higher mountain of Babadag reaches of northeastern Hierapolis are sited on the Principal travertine deposits l Hierapolis AKKOY 0 500 m Hierapolis fault zone • village ~ • •'rl" active normalfault ~DEVELI T-T" range front fault . ~ i IERAPOLIS terrace-moundtravertine \ • I fissure-ridgetravertine CITY WALL older travertines ~ N:c~ugdnn~ trn:veQ~nat:srn ary ' ~ m Nre- eooeoe l PAMUKKALE Fig. 3. Map of the distribution of morphological varieties of travertine and active faults in the Hierapolis area (based on Altunel & Hancock 1993a). It should be noted that the large outcrop of actively depositing terraced-mound travertine near Pamukkale is sited in the hanging wall of the Hierapolis fault zone. Downloaded from http://sp.lyellcollection.org/ by guest on September 25, 2021 CREATION AND DESTRUCTION OF TRAVERTINE MONUMENTAL STONE 5 Pamukkale range front, and about 30m above the lower level, which contains most of the travertine deposits (Fig. 3). The southern seg- ment of the slope between the two terraces of this divided plateau is the site of the most spectacu- larly white of the actively depositing travertines. The major valleys, which coincide with the Menderes and Gediz grabens, were important routeways for peoples and armies travelling either west or east between the Aegean coast- lands and the central Anatolian plateau, a region that gave access to the upper Euphrates valley and from there to Persia and further east (see Ramsay's (1890) map of routes in ancient Asia Minor). Although the Menderes graben pro- vided the easiest pathway from the Aegean coast via Tralles (modern Aydin) and Nyssa to the interior, the Gediz graben was also a vital route connecting Magnesia (modern Manisa), King Croesus' city of Sardis and Philadelphia (modern Alasehir) in the Gediz graben to the cities of Tripolis, Hierapolis, Laodicea and Colossae in the Denizli basin. Because the Denizli basin lies at the con- fluence of two major routes from the coast to the interior and because it is a large area of relatively level and well-watered ground close Fig.