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JENKINS— GEOLOGY OF THE 



[May 29, 



at a distance of about thirty-five kilometers, and returns at low tide. 

 This action is utilized by the people who travel up and down the 

 river only by tides. The present silting up of this great channel and 

 many others like it is extremely interesting because it shows a 

 sunken coast. The sea has intruded into the stream channels and 

 later it has been driven out by the deposition of silt. 



TJie Plateau Region. 



The surrounding region is a low, sandy, gently rolling plateau 

 covered with shrubs not much over two and a half meters in height. 

 The small scrubby rubber tree is its typical plant. Farther back into 

 the interior the hills become a more prominent topographic feature, 



Fig. 3. Topography, looking from Taipu, in the rolling hills of the interior, 

 towards the flat plateau region along the coast, Rio Grande do Norte. 



for they are in the crystalline series of rocks. As one travels over 

 the plateau region, its flatness appears unbroken, but occasionally 



Fig. 4. Topography, looking northwest from Taipu in the rolling hills towards 

 the higher, interior country, Rio Grande do Norte. 



