"We can perhaps best 

 appreciate the process 

 by which these lakes 

 are made by returning 

 in our roiuds to the 

 conditions that must 

 have prevailed about 

 the end of the period 

 during which these 

 sediments were depos- 

 ited. The beds were 

 then at or below sea- 

 level; subsequently 

 they were lifted verti- 

 cally from beneatli the 

 water and stream ero- 

 sion began to cut val- 

 leys in them, while 

 the waves of the sea 

 attacked their margins. 

 In the course of time 

 broad valleys were 

 eroded out where we 

 now have Lagoa do 

 Norte, Lagoa Mangu- 

 aba, Jiquia, etc. After 

 the cutting of these 

 valleys there came a 

 downward movement 

 which carried the bot- 

 toms of all of them 

 below the level of the 

 sea, and made bays of 

 them. But inasmuch 

 as land erosi^on con- 

 tinned over the part 

 still out of water the 

 streams carried their 

 sediments into these 

 bays and began to silt 

 them up. The sea also, 

 cutting sands from the 

 headlands, threw them 



f^ 



