10 



SOPER— GEOLOGY OF PARAHYBA 



the southeast of Assi'i, the contact is exposed again. Thereafter it 

 was found about 4 kilometers south of Baixa Verde (the village — 

 not the railway station), and again a little to the north of the rail- 

 way station — Itapassaroca. At Ceara Mirim the limestone is 31 

 meters below the surface (near the church), and it has been noted 

 about 20 kilometers west of Natal, near Macahyba. South of Natal 

 the writer has not explored the limestone, but Dr. J. C. Branner^ 

 reports that it is found near Sao Jose, Goianinha, Pequiry and Para- 

 hyba. Hence it is probable that the same geologic relations exist to 

 the south of Natal, as are known to exist to the north. 



Fig. 2. Section across the Chapada do Apody. 



The limestone exposed in the strip above mentioned has a vary- 

 ing width, which reaches its maximum in the vicinity of'Mossoro. 

 Here a cross section would show a width of at least 70 kilometers. 

 At Assu probably 25 kilometers would cover it. From Baixa Verde 

 a section east would show the limestone to be about 16 kilometers 

 wide while in the vicinity of Natal it is probably less than 10 kilo- 

 meters across. 



The only place where the structure was clearly seen in the lime- 

 stone was along the scarp of the Chapada do Apody and along the 

 Rio Apody, from Passagem Funda to Sao Sebastiao. There, rock 

 dips toward the northeast ; in places it is horizontal. At the fazenda 

 Sussarana, 23 kilometers northeast of Apody, and again near the 

 village Sao Sebastiao, Mr. Crandall, in the paper previously re- 

 ferred to, reports that he observed the sandstone underlying the 

 limestone. This means that in spite of the apparent seaward dip the 

 beds are horizontal, or approximately so. Furthermore, a well has 

 been drilled in Mossoro to a depth of 45 meters. The first 30 meters 

 were in limestone and the last 15 in sand. Judging from this the 



^ J. C. Branner, " Geology of the northeast coast of Brazil," Bulletin of 

 Geological Society of America, Vol. XIII., pp. 93-95. Rochester, 1902. 



