Massive discharge of mud from coastal rivers is a well-documented phenomenon. However, in areas with limited historical and instrumental records it is often difficult to assess the nature and history of the process.This article looks at Tijucas Bay, in southern Brazil (Figure 1a) (an area that was the landfall region in March 2004 for South America's first recorded hurricane <Bossack, 2004>), to examine the time frame for extensive deposition of fluid muds in the nearshore )Figure 1b(. The new geological data suggest that whereas recent human activities (e.g., massive sand mining) along the Tijucas River may be important in increasing the suspended sediment discharge, the shift to a mud-dominated regime was part of the natural evolution of this coastal plain.