RESUME OF GEOLOGY ALONG ESTRADA CENTRAL 85 



It should be added that I felt convinced while looking at them in the 

 field that many of the rocks in and west of the Serra da Russa were 

 metamorphosed sedimentary beds. The rock described by Mr Iddings 

 belongs to what I supposed to be a metamorphosed tuff of some kind. 

 Mr Iddings tells me that this is not impossible, but that there is nothing 

 in the slides alone to show it. 



I am further induced to think these rocks are rhyolitic tuffs partly by 

 their constant evidence of bedding, by their association with shales, and 

 by the agreement of their strike with the strike of the limestones at Sao 

 Caetano, as reported by Dombre. 



CONCLUSIONS REGARDING GEOLOGY ALONG THE CENTRAL RAILWAY OF 



PERNAMBUCO 



1. The Tertiary (?) beds are exposed along the Estrada Central only 

 to kilometer 13 from the Pernambuco end of the line. 



2. The topography about Areias and Tigipio suggests a late elevation 

 and a still later depression of the region. 



3. Whether the granites are older or newer than the schists is not clear 

 from anything observed along this geologic section. 



4. The colors of the residuary clays are much more brilliant from just 

 west of Francisco Glycerio eastward — that is, from sealevel up to an 

 elevation of about 200 meters — than they are at a greater elevation and 

 west of there. 



5. West of the Tertiary area the railway passes over granites, gneisses, 

 and schists. From Russinha westward there are a few places at which 

 stratified rocks are exposed. Some of these resemble altered tuffs and 

 some are shales. 



6. The bedded rocks include remarkably pure limestones (marbles) 

 south of Sao Caetano, and these marbles also have an east-west strike. 



7. Some of the metamorphosed beds have the felted appearance char- 

 acteristic of certain Paleozoic rocks of the Minas Geraes highlands. 



8. The region west of the Serra da Russa seems to be much faulted, 

 the faults following the east-west strike of the rocks. 



Geology along the Great Western Railway from Pernambuco to 



TlMBAUBA* 

 RAIL WAY STA TIONS 



The following is a list of the stations, with distances and elevations : 



*The author is indebted to the Pernambuco officers of the railway company for free transpor- 

 tation over the line for himself and five assistants and for every courtesy and attention that could 

 add to the pleasure and interest of the trip. 



