88 J. C. BRANNER — GEOLOGY OF NORTHEAST COAST OF BRAZIL 



Figure 10.— Section on the Railway between Pao d'Alho and 

 Carpina. 



the decayed mass are rounded (exfoliated) lumps of the unaltered rock. 

 This cut is about 150 meters long. Near the top of the bank is a thin 

 line of waterworn pebbles following the contour of the hills. 



At Santa Rita, Sao Severiano, and Pao d'Alho the crystalline rocks 

 are well exposed in the river bed. Below the bridge at Pao d'Alho the 

 schists are decayed in place and exhibit the same bright colors as are 

 found in the Tertiary sediments. ' 



Beyond Pao d'Alho the slopes of the hills are gentler and the valleys 

 broad, and the watersheds far away. On the hills between Pao d'Alho 

 and Carpina (about 3 kilometers south of Carpina) the decayed crystal- 

 line rocks are covered by a 

 layer of red clay, near the 

 bottom of which is a layer 

 of waterworn pebbles min- 

 gled with angular and sub- 

 angular fragments of gneiss. 

 In every observed instance 

 these bands of pebbles follow the contour of the hills and are within 

 2 meters of the surface of the ground. In some places — not hilltops — 

 the waterworn pebbles are 5 meters below the surface of the ground. 



Carpina (kilometer 59.8), it will be observed, is the highest point on 

 the road (182 meters), and is on the watershed between the Capibaribe 

 and Rio Goyanna. Looking northward from Carpina the mountains 

 on the horizon have a serrate outline ; toward the northeast they are less 

 broken, while to the southeast the skyline is even and horizontal. To 

 the east of Carpina, about 3 kilometers, there is one high peak that over- 

 looks the surrounding country. 



Between Tracunhaem (kilometer 67.2) and Nazareth gneisses and 

 some granites are exposed by the railway track, but there are no water- 

 worn pebbles in the soil. At Nazareth station (kilometer 72.9) the 

 gneiss is wrinkled and decayed. At the little station of Junco, between 

 Nazareth and Lagoa Secca, the decayed rocks look more like schists than 

 like gneisses. One of the cuts is about 20 meters deep, and the decayed 

 rocks are mostly red. About 150 meters beyond the station of Lagoa 

 Secca (kilometer 84.1) a cut exposes a narrow band of waterworn peb- 

 bles in the soil. 



At Barauna station (kilometer 91.2; elevation, 73.6 meters) the rocks 

 are schists. 1 n the railway cuts 300 meters beyond the station the schists 

 are deeply decomposed, and bands of waterworn pebbles pass through 

 the thick clays and sands that overlie the rocks deca} 7 ed in place. Two 

 or 3 kilometers beyond the station these clays and sands are from 6 to 



