floor sediments by Swift, Stanley, and Curray (1971) who called the 

 sediments "palimpsest" deposits. 



In general, the medium to coarse sand and shelly sand of the inner 

 shelf floor surficial deposits are probably the result of either sediment 

 transport or reworking of substrate deposits in waters much shallower 

 than now exist over the area. Present shelf processes in most of these 

 areas, however, are probably effective in removing the finer detrital 

 and biogenic sediment particles which accumulate during periods of fair 

 weather. Evidence of the latter process is the usual scarcity of foram- 

 inifera in the medium and coarse sand areas as compared to nearby areas 

 of fine sand and also that many of the tests that occur in the coarser 

 deposits are of large size. Since both fine and coarse surface sands 

 occur in close proximity and at about the same depths in many places, 

 the modem benthonic foraminifera can reasonably be expected to be near 

 equivalent in both abundance and kind unless substrate character is of 

 decisive importance, but this seems unlikely. The probable reason is 

 that coarser sands are located in areas where strong wave and current 

 flow either prevents establishment of smaller foraminifera or periodi- 

 cally winnows out their discarded tests. 



In contrast, many of the finer shelf facies sand deposits probably 

 occupy areas where deposition is the dominant process under existing 

 conditions. The foraminifera in these sand deposits, unlike the nearby 

 coarser sands, have a higher abundance, greater species variability, and 

 a predominance of small tests. In addition, the fine deposits contain 

 large numbers of other small biogenic particles, such as echinoid spines 

 and mo Husk larvae, which are rare in the coarser facies. 



Not all the fine shelf facies sand deposits, however, are located in 

 modern depositional environments. Some deposits consist of locally re- 

 worked fine sands of type B or C sediment which may have originated during 

 the transgression. 



In a few cases, fine sand on the surface consists of exposures of 

 type B or C sediments which are probably being actively eroded, at least 

 on a periodic basis. For example, at core 80 the surface is an exposed 

 type B deposit containing abundant Oligocene foraminifera but practically 

 no modem types. This indicates fresh surfaces had recently been or are 

 continually being exposed by erosion. Therefore, it is judged that while 

 many shelf facies, fine sand deposits occupy areas of probably active 

 deposition, some occur where there is little or no deposition now taking 

 place and a few occupy areas of active erosion. 



The major source of the fine shelf facies sand apparently lies in 

 the extensive Cretaceous and Oligocene fine sand and muddy sand deposits 

 underlying large parts of the inner shelf. Most of the sand was probably 

 originally eroded from these deposits during the transgression, but quan- 

 tities of fine sand are now being derived by winnowing of coarser shelf 

 facies sand and by active erosion of exposures of Cretaceous and Oligo- 

 cene strata. 



71 



