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Annals of the Carnegie Museum. 



schist, and pegmatite, are shown in the sketch map (text-figure 2). 

 Much of the siliceous material seems to be in the form of veins and 

 lenses of quartz, but the wider areas may be of quartzite. In the 

 main the limestone outcrops as a series of craggy masses (Cf. Plate X, 

 fig. i), along a zone about one-half kilometer wide, which extends 

 in a nearly straight line S. 60° W., magnetic, for a distance of five 

 kilometers. The northeasternmost outcrop observed is on a steep 

 hillside of white quartz (or quartzite), and the southwestern exposure 

 culminates in a prominent pillar called 'Frade' = The Monk (Cf. 

 Plate X, fig. 2), which is at the northwestern base of the steep quartz 

 or quartzite slopes. In the area lying north of the main zone small 

 outcrops of limestone were seen beside the railroad near Itapahy 

 station, a few kilometers northwest of the Trade,' and at the margin 

 of a pond between the northeastern end of the zone and i\carape. 

 The limestone masses seem to be bordered on each side by quartz. 

 Quartz (or quartzite) slopes rise directly south and east of the pillar 

 'Frade,' and a boulder near the pillar exhibits a contact zone about 

 one meter wide, of alternating bands of quartz and liinestone, as 

 shown in Text-fig. 3«. In the railway cut one-half kilometer south- 



FiG. 3. a. Section showing alternation of quartz and limestone in a boulder at 



'Frade' near Acarape, Ceara. 



b. Section showing alternation of quartz and limestone in railway cut, one-half 



kilometer S. E. of Itapahy Station near Acarape, Ceara. 



east of Itapahy bands of limestone and quartz are exposed as shown in 

 Text-fig. 36. The limestone is not exposed on the opposite (western) 

 side of the railroad cut, which is of gneiss, with a smooth surface like 

 that of a movement plane. The pegmatite dikes in the northeastern 

 portion of the quartz and limestone area seem to strike in the same 

 direction as the limestone; but in the area of schist between "Frade" 

 and Itapahy a small pegmatite dike trends southward until it meets 

 the quartz and then disappears. 



