Figure 4. (a) Orbital climatic (OC) diagram constructed for climatic significance coefficients in the proportion of 1 : 0.7 : 0.55. Conventional D P units represent the relative probability of cooling events (for negative values) and warming events (for positive values). Shaded areas with D P <- 0.5 are interpreted as periods of the greatest probability of glaciation. Numerals at these areas denote the respective oxygen isotope cool stages. (b) Comparing the OC diagram (dashed line) to the oxygen isotope (OI) curve [Shackleton, 1995]. d18O, the change of the heavy oxygen isotope in ocean water. Numerals at the oxygen isotope curve are the numbers of oxygen isotope stages, even numbers marking glacials, and odd numbers, interglacials. The abscissa is time in thousand years B.P.