The study of Libyan stratigraphy received a huge boost with the arrival of the oil companies and the discovery of oil in 1955. Since then enormous progress has been made in age dating based on fossils and radiometric techniques. Combined with downhole logs from thousands of wells and seismic data from thousands of kilometres of seismic lines it has been possible to establish reliable lithostratigraphic correlations over large areas. The arrival of seismic stratigraphy allowed the recognition of facies changes within formations, and the more recent development of sequence stratigraphy has permitted the integration of sequences into schemes of global sea level fluctuations and regional tectonic events. There are however a number of problems. There are two systems of stratigraphic nomenclature currently in use in Libya, one based on surface observations and a second based on subsurface data. Neither system is complete, and there is very limited integration between the two schemes, particularly in the Sirt Basin. In Cyrenaica there are virtually no formation names for any of the subsurface units which do not outcrop. Furthermore there is a big problem in the orthography of stratigraphic names, since the method of rendering Arabic names into western script has changed several times in recent years.