The longest geological cycle identified is described as about 600 million years in "Megacycles", the proceedings of a geological conference,...
The longest geological cycle identified is described as about 600 million years in "Megacycles", the proceedings of a geological conference, Edited by G Williams. However Prof S Afanasiev of Moscow has determined the cycle very accurately to be 586.24 million years using his Nanocycles Method.
It so happens that cosmologists, Broadhurst, T.J., Ellis, R.S., Koo, D.C. & Szalay (Nature 343, p 726) have observed regular mega-walls of galaxies at spacings that they describe as 128 Mpc/h, which based on the latest Hubble constant values would correspond to 588 million light years. Some cosmologists have suggested that the regularity might result from standing waves.
Standing waves in space of wavelength 586 million light years would oscillate in 586 million years. In addition, if there are present harmonics of these waves as both the geological cycles and the additional peaks in the galaxy survey indicate, then powerfully energetic events would recur on Earth at these intervals. This agreement on the wave sizes actually allows a much more accurate Hubble constant to be determined from Afanasiev's accurate cycle period.