Top plot: the summary curve of two magnetic field waves, or PCs, calculated backward ten thousand years from the current time. The vertical lines define the similar patterns in five grand cycles repeated every 2000–2100 years (a super-grand cycle). Bottom plot: the oscillations of the summary curve (cyan line) calculated backward from 70 K to 90 K years overplotted by the oscillations of a magnetic field baseline, or its zero line (dark blue line) with a period of about 1950 ± 95 years. The baseline oscillations are obtained with averaging running filter of 1000 years from the summary curve suppressing large scale cycle oscillations. The left Y-axis shows the scale of variations of the baseline magnetic field, while the right Y-axis presents the scale of variations of the summary curve.