432 JENKINS— GEOLOGY OF THE [May 29. 



Brazil that included all that was then known of the geology of the 

 coast of Rio Grande do Norte from Natal to the southern edge of 

 the state. That paper contained a sketch map showing the coastal 

 belt of sedimentary rocks. 



The work of Mr. Jenkins, done in 191 1, has added much to 

 our knowledge of the region, especially to the north of Natal, and 

 it has definitely located the landward margin of the sedimentary 

 beds. 



It has also disclosed an unconformity in the sedimentary beds 

 that seems likely to clear up the long standing question in regard to 

 the existence of the break between the Cretaceous and the Tertiary 

 in this part of South America. Some of my own geological obser- 

 vations made in 191 1 have been incorporated in Mr. Jenkins' paper, 

 while specimens of crystalline rocks from near Baixa Verde, exam- 

 ined microscopically and described by Mr. Jenkins, were collected 

 by Mr. Earl Leib another member of the expedition. 



J. C. Branner, 

 Director of the Stanford Expedition to Brazil. 



Stanford University, California, 

 May 6, 1913. 



Introductory, 



In the summer of 191 1 the Stanford Expedition to Brazil made 

 its headquarters for six weeks at Natal, in the state of Rio Grande 

 do Norte, 5° 45' south latitude, 35° 12' west longitude. During 

 this time most of the members of the party were engaged in col- 

 lecting zoological material. Occasional inland trips were made 

 which gave means for determination of geological data. These trips 

 were along three lines, each of which went far enough into the 

 interior, about forty or fifty kilometers from the coast, to reach the 

 crystalline series of rocks : 



1. To the northwest by railroad — "Estrada de Ferro Central do 

 Rio Grande do Norte " — to Taipu and Baixa Verde. 



2. To the south and southwest by the " Great Western Railway 

 of Brazil," which extends for many kilometers down the coast. 



3. To the west by boat up the Rio Jundiahy to Macaliyba. 



