4:40 Lisboa — Permian Geology of Northern Brazil. 



has an altitude of about 100 meters. It is in this region that 

 a very ferruginous calcareous sandstone, or sandy limestone, 

 appears. Little bowlders of this limestone are strewn along 

 the road for great distances. They remind one of a bed of 

 brecciated conglomerate, loosened at the surface but composed 

 exclusively of limestone. In this respect, this sediment is 

 similar to those of Grajahu.; the bed with blocks of limestone 

 covers this gypsiferous rock, and the eruptive flows separate 

 it from the overlying sandstones. 



The limestone -continues about eight kilometers beyond 

 Taboa do Raymundo Felix. From there on there are abundant 

 flints and a quartzitic sandstone which grades to a white sand- 

 stone of a reddish or yellowish tinge. Between Fazenda 

 Moreira and the Clemente is a bowlder bed, the flints of which 

 strew the ground. Like those of limestones and of the erup- 

 tives of Grajahu, these fragments of rock, laid on the surface 

 of the ground, seem to come from a nearly horizontal sedi- 

 mentary bed which contains them, cropping out along the 

 surface of the ground. They bring to mind a breccia of dis- 

 integrated sandstone. 



The Chapada do Corda rises from 100 to 120 meters on an 

 average, and falls away about 80 meters on the side overlook- 

 ing the city, near the river. At the base of the chapada, in 

 the channel of the river, the bituminous shale appears beneath 

 the limestone with its siliceous beds. 



The descriptions given above will enable those who are 

 acquainted with the Permian geology of both northern and 

 southern Brazil, taking into consideration the neighboring 

 occurrence of the Parnahyba series, to consider these limestones 

 and sandstones with flints and siliceous laminations as Permian. 



The difficulty of placing these sediments in the geologic col- 

 umn in the Maranhao system lies in the impossibility of recog- 

 nizing the direct relations with the Permian sediments of 

 Therezina or of the tableland which separates Caxias from 

 the Parnahyba. In the Grajahu. region also the succession of 

 the sediments is not very clear. 



There are bituminous schists in the Cretaceous in Ceara, 

 at the base of the Araripe beds, near a basal limestone, and 

 near this same limestone is a gypsiferous bed, two leagues 

 from Santa Anna, on Fazenda Angicos. This occurrence has 

 not been examined by a geologist and the stratigraphic rela- 

 tion of the sediment is not yet known. 



The examination of the bituminous shales of Inferno and a 

 rapid reconnaissance between Codo, Caxias, and Therezina will 

 easily solve this important problem of the geology of Maranhao. 



The calcareous and sandstone sediments with flints of the 

 Pocos limestone and the Cigana sandstone show the age to be 

 Permian, so far as can be determined by observation in Brazil. 



The fossil conifers collected by me in the region of the bitu- 



