The Prebetic zone of the Jaen region, Spain, consists of three main units. The Castillo unit on the north consists of Vraconian? and Cenomanian (Cretaceous) limestones thrust over the Tertiary; next is the Pena de Jaen unit, consisting of similar but more fossiliferous and more neritic beds; the thick Jabalcuz-Los Villares series on the south (Liassic to Cenomanian) is thrust over the Pena de Jaen unit. Thus parautochthonous, subautochthonous, and autochthonous masses are all represented in the Prebetic zone. The concept Prebetic is becoming more purely structural than has been the case in the past; it is applied to all the sedimentary formations below or before the vast Subbetic overthrust.