Archaeomagnetic Studies of the Urartian Civilization, Eastern Turkey

Article excerpt

Introduction

Archaeomagnetism offers a method, established by Thellier (1938), for dating fired structures or objects by comparing the magnetization acquired as they originally cooled, with the properties of the Earth's magnetic field at that time. We present here the first archaeomagnetic study of Bronze Age sites in Eastern Turkey. As the geomagnetic field properties for this time and area are not known, these observations are correlated with observations in Bulgaria (Kovacheva 1980), the Ukraine (Rusakov & Zagniy 1973) and Iraq (Hammo-Yassi 1983).

Three localities were sampled -- Cavustepe (CA), Dilkaya (DI) and a cemetery next to Van Castle (VA). All samples were collected by the disk method (Tarling 1983); nonmagnetic disks are glued to the objects and then oriented, using a sun compass, before removing them with a small piece of the object, generally c. 8 cu. cm, attached to it. Incremental demagnetization of the remanence was undertaken on all but 5 samples using alternating magnetic fields (3, 5, 7.5, 10, 15, 20, 30, 40, 50, 60, 80 & 100 mT peak) in order to remove any magnetizations acquired subsequent to the last firing. Incremental thermal demagnetization (20, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550 & 600[degrees]C) was undertaken on 5 Cavustepe samples to determine whether their last firing temperature could be estimated and to ensure that the original single component of remanence had been satisfactorily isolated. In all sites, the magnetic remanences of the samples were measured using spinner magnetometers and each demagnetization vector was analysed independently for stability and principal components. The linear vectors were defined as having a diagonal error of [greater than or equal to]5[degrees] (Kirschvink 1980), although all linear components with diagonal errors of [greater than or equal to]10[degrees] were examined.

Cavustepe

This fortress, some 25 km south of Van at 38.27[degrees]N 43.50[degrees]E, was built on a pristine site on an 800-m high limestone ridge by the Urartian king Sarduri II (Sardun or Seduri in Assyrian texts) in the middle of the 8th century BC. It comprises two main units (FIGURE 1) separated by a col and has been excavated by Afif Erzen (1987). The upper, eastern and smaller part is largely a temple (D) dedicated to the god Haldi. The lower, western part of the fortress, consists of a palace complex (A) and a temple (B) dedicated to the god Irmusini. The palace, some 81 x 33 m, includes solid-rock water cisterns and an advanced plumbing system, including water supplies directly to the kitchen and a royal latrine. One of the several rooms (C) between the palace and the temple, c. 5 x 20 m, contained 52 large Urartian pottery storage jars, each some 2 m high; the room had been backfilled, leaving only the c. 1-m diameter rims exposed. These vessels contained large quantities of grain that had been burnt, presumably when the entire fortress was destroyed and burned by the Medes about 590 BC. Five of these storage jar rims were sampled in the granary storage area on the west (locality C on FIGURE 1), including symmetrical sampling (6--7 samples) of the rims of 3 vessels (CA1, 4 & 5). One fired clay vessel, also c. 1 m in diameter, was also sampled (CA7) on the higher eastern side, c. 50 m east of the entrance to the Haldi temple. This jar, also Urartian and c. 1 m in diameter, is of unknown purpose. Areas of natural limestone, reddened by the heating assumed to have occurred during the destruction of the entire site, were also sampled (CA6) at the entrance to the Irmusini temple. All sampling was undertaken on 26 August 1989.

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Results

Storage vessels (CA1--5)

(i) Alternating magnetic field demagnetization behavior

All samples behaved similarly to incremental demagnetization with very little sign of low coercivity (viscous) components; one clear vector was present in most samples (TABLE 1 & FIGURE 2b) although most isolated vectors did not include the initial natural remanence determination. …