This paper deals with the results of a geologic mapping carried out in scale 1:200,000, for an area of 1,470 km2, located in the northwestern part of Ceara State. The main stratigraphic, structural and lithologic features of the following units are discussed: a) migmatite and quartzite of indifferentiated Precambrian age; b) metasediments of the late Precambrian Bambui Group (slates, quartzites and limestones); c) the Ordovician Jaibaras Group, made up by a molassic sequence (feldspatic sandstones), by a hornfels aureole due to the thermal effects of the Mucambo granite intrusion, by andesite and by polymictic conglomerates of "piedmont" type. The tectonics and geological evolution of the area are also briefly discussed.This paper deals with the results of a geologic mapping carried out in scale 1:200,000, for an area of 1,470 km2, located in the northwestern part of Ceara State. The main stratigraphic, structural and lithologic features of the following units are discussed: a) migmatite and quartzite of indifferentiated Precambrian age; b) metasediments of the late Precambrian Bambui Group (slates, quartzites and limestones); c) the Ordovician Jaibaras Group, made up by a molassic sequence (feldspatic sandstones), by a hornfels aureole due to the thermal effects of the Mucambo granite intrusion, by andesite and by polymictic conglomerates of "piedmont" type. The tectonics and geological evolution of the area are also briefly discussed.