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 not only the 11-year cycle, but also resonances at 5.5 and 2.75 years in Precambrian “varved” sediments consisting of annual layers. added other examples in his 1972 book .
