I9I3] REGION ABOUT NATAL, BRAZIL. 463 



IVater-Supply. 

 The abundant rains along the coast sink into the sand immedi- 

 ately, but on coming in contact with the clayey beds of the sand- 

 stone series below, they are not able to pass farther down, so they 

 emerge at low places. These low places are often between sand- 

 dunes. Thus along the sea-coast, natives draw water from holes dug 

 in the sand and the water is soft and fresh. 



Fig. 12. General section of the coastal sand-dunes, showing how the fresh- 

 water springs occur. Rain sinks through the sand-dunes and emerges where 

 impervious beds of the clayey sandstones are exposed. 



On the opposite side of the river from Carnahubinha there is a 

 place called Agua Doce. Here excellent drinking water is obtained. 

 The sand-dunes form an amphitheater around one side of the small 

 depression, which is about fifty meters across. The water is bub- 

 bling up all the time and carries away the sand as fast as it is blown 

 into it. Fresh water occurs in a certain point in the river near this 

 place, although the river carries salt water from the sea. Here 

 it is said that a hole twenty-two meters deep is present, while the 

 rest of the stream has only the depth of six meters.'^ Similar holes 

 usually occur near the bank where a sand-dune is present. 



This form of spring supplies the small lakes of the plateau 

 region with water the year around, as in the region north of Papary. 

 Here, along the border of some of the lakes, such as Logoa Bom 

 Fim, such springs were found feeding the lake directly. 



The rivers carry the water down from the interior. Often they 

 are dammed at their mouths and form lakes. These lakes are val- 

 uable to the people, whose villages are clustered about their shores, 

 as at Papary. 



Farther into the interior the lack of water is a serious matter. 

 Sometimes great droughts drive the inhabitants from the country. 



"' Information obtained from Mr. J. D. Smith at Carnahubinha. * 



PROC. AMER. PHIL. SOC, LU. 211 L, PRINTED SEPT, l6, I9I3. 



