The Lorca Basin is located in the Betic Ranges (SE o f Spain) over the contact between the Betic domain s.s. (in te rn a l zones) and the Subbetic one (external zones). For the complementary use of the mineralogical and tectosedimentary analysis it has been necessary the realization of the geologic cartography. It have been differentiated five continental formations of the Quaternary and twelve neogenes formations dated from the upper Burdigalian to the Pliocene. They were originated in marine environments with entrance of continental contributions except for the upper Messinian-PUocene which have a fluvial-lacustrine origin. The most abundant material are marls, sandstones, lutites, gypsiferous levels, conglomerates, sands and limestones