GENERAL AND ECONOMIC GEOLOGY 



245 



General geology. — The surface rocks over most of the State of Ceara 

 are the granites, gneisses, and schists of the Brazilian complex. Along 

 the western frontier the Serra Grande monntain range is of sedimentary 

 rocks that have been called lower Permian by Small and Cretaceous by 

 Crandall. The Araripe range, which lies along the southern boundary, 

 is Cretaceous, while the entire coast is bordered by a narrow belt of Ter- 

 tiary sediments. The Archean of Ceara is cut at many places by intru- 

 sives, and faults have let down into the granites and gneisses the ends of 

 some of the old sedimentary beds that now appear in the topography as 

 ridges of quartzites. A typical instance of this structure is shown in the 



Piauhyl Ceara 



Chapada do Araripe 



Cole cure de SantArma 

 con-peix05 fosseis 



vV /"~-^ '^■^ I \Fiq cha3lc7ystallinaJ'^ V"'-1 V/i77T't^V^'^'y^»i l£kl^°"A '|'< j^ ciriq^^ &tg ii QO —'T^^^^^^ ^^'''.^*^^^^ 



5ec9ao geolo^ica mostrando a estructrua da Chapada do Araripe. 



Conforme H.L. Small. 



ffon zonte dos paixe^s fo sse,is 



Chapada do Araripe 



N.E. 

 Serra da Maosinha 



Seccao ^eolo^ica.da Chapada do Araripe entre 5erra da Mao5inha e Jardim. 



Conforms H.L.Small. 



Figure 11. — Tico Sections shoicing the geologic Structure of the Chapada do Araripe, in 



southern Ceara 



The fossil fishes are from the Sant'Anna limestone. — H. L. Small. 



Serra de Tucunduba, whose geology is given in the report of H. L. Small 

 oj^posite page 46. There are also a few isolated infolded or infaulted 

 fragments of some of the newer rocks scattered over the Archean area. 



The Lower Permian — the "Serra Grande series" of Small-^forms the 

 eastern escarpment of the Serra Grande, a range of mountains on the 

 western frontier, extending from near the ocean on the north to seven 

 degrees south latitude, nearly to the Serra do Araripe. The rocks of the 

 Serra Grande are coarse calcareous sandstones, limestones, and conglom- 

 erates, usually false-bedded, and having a maximum thickness of TOO 

 meters just west of the town of Ipii. For the most part the dip of these 

 beds is from four to seven degrees toward the west or northwest. No 

 fossils have been found in the Serra Grande rocks, and the ao-e of the 



