It was formed during the Middle and Lower Miocene (20 to 15 million years ago). The colour code on the geological map is light brown, dark brown and yellow because it is subdivided into three layers however for practical reasons it is coloured just yellow on the this geological map. It is exposed from a thickness of 23m (Chambrai, Gozo) to about 207m (Marsaxlokk). It covers around 70% of the area of Malta. It is a rather soft limestone of yellowish to greyish colour.
Below: A Globigerina Limestone Shore Platform, a common geomorpholigical feature of Globigerina Limestone where it meets the sea.