EarthRef.org Digital Archive (ERDA) -- The Geomagnetic field in Peking Region and its secular variation during the last 2000 year

Description
The results of the archaeomagnetic study of the geomagnetic field in Peking region and its secular variation during the last 2000 years are presented. The authors have measured the intensity of the natural magnetization of a number of ancient brick samples of known ages collected in Peking region for the last 2000 years. From these measurements the geomagnetic inclinations are deduced. The total intensities of the geomagnetic field are determined by means of Thellier's method of heating step by step. The results clearly show that the inclination in Peking varies between 51 degrees - 66 degrees during the last 2000 years, and has a cyclic variation, the period of which is about 1000 years. The total intensities F at the epoch of Han (206 B.C. - 219 A.D.), San-Kuo (220 - 280 A.D.), T'ang (618 - 905 A.D.), Sung (960 - 1276 A.D.), Yuan (1280 - 1360 A.D.), Ch'ing (1644 - 1911 A.D.) are respectively 1.57, 1.41, 1.42, 1.29, 1.21, 1.12 times of that of the present field in Peking, the F decreases gradually with time during this period.