From Bruce Denness, Whitwell, Isle of Wight, UK
Michael Marshall reports that a team from the China University of Geosciences in Beijing has found evidence of the 11-year solar sunspot cycle in Precambrian sedimentary rocks of south China (18 August, p 6). More than 50 years ago, Roger Anderson observed not only the 11-year cycle, but also resonances at 5.5 and 2.75 years in Precambrian “varved” sediments consisting of annual layers. Hubert Lamb added other examples in his 1972 book Climate Present, Past and Future.
