Phosphorite genesis correlates in a general way with elevated sea level and warm climate and is therefore influenced by plate tectonics and continental drift. Phosphorite genesis correlates more specifically with transgression -- a result of the interaction of continental hypsometry, tectonic perturbation and eustatic effects -- whereby a small number of shallow slope and shelf sites are available for phosphate fixation. Phosphorite genesis correlates with warm climate. Oceanic anoxic events (OAE's : episodes of world-wide deposition and preservation of organic carbon), which also correlate with particularly high sea level stands, generally do not coincide with major phosphorogenic episodes. In contrast to the assertions above, the permian Phosphoria Fromation was deposited during a marked overall global low-stand of sea level. However, the phosphatic sequences were laid down during brief transgressive episodes.