U.S. DEPARTMENT OF THE INTERIOR / U.S. GEOLOGICAL SURVEY
                                
                                
        U.S. GEOLOGICAL SURVEY DIGITAL DATA SERIES DDS-13
                                
              International Phase of Ocean Drilling
                Seismic Line 1 Demultiplexed Data
               Cape Hatteras to Mid-Atlantic Ridge
                                
                            DISC ¯28

Demultiplexed Seismic Data

     Each file of seismic data is the disc-image of a SEG-Y
format tape output during the demultiplexing of the original
field data.  The data were written to tape using the 32 bit IBM
floating point format (Barry, and others, 1975).  As the data
were copied bit-for-bit to the CD-ROM file, this format was
preserved.  Each file of sesimic data is named IPD{number}, where
{number} is the first shotpoint in the file.  NOTE: FFID
indicates the Field File Identification Number assigned each shot
as it was recorded.

             file:  ¯IPD23346.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯136478980
   traces in file:  ¯21205
      first trace:  ¯694/9 FFID/trace
       last trace:  ¯135/45 FFID/trace


             file:  ¯IPD23567.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯67678140
   traces in file:  ¯10515
      first trace:  ¯135/46 FFID/trace
       last trace:  ¯462/48 FFID/trace


             file:  ¯IPD23732.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯137740436
   traces in file:  ¯21401
      first trace:  ¯465/1 FFID/trace
       last trace:  ¯911/41 FFID/trace

                             1

             file:  ¯IPD23954.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯134934340
   traces in file:  ¯20965
      first trace:  ¯911/42 FFID/trace
       last trace:  ¯786/44 FFID/trace

             file:  ¯IPD24173.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯134786312
   traces in file:  ¯20942
      first trace:  ¯348/31 FFID/trace
       last trace:  ¯786/44 FFID/trace



Observer Logs

     The following files are digitized versions of the original
observer's log sheets.  Each file is named OB{number}.{format},
where {number} is the first shot point on the page, and {format}
is the graphic format of the file: PCX, TIF, or GIF.  No {format}
extension is shown with the file names given below.

OB23300
OB23350
OB23400
OB23450
OB23500
OB23550
OB23600
OB23650
OB23700
OB23750
OB23800
OB23850
OB23900
OB23950
OB24000
OB24050
OB24100
OB24100G
OB24150
OB24200
OB24250
OB24300
OB24350

                             2


REFERENCE

Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended
     standards for digital tape formats: Geophysics, v. 40, p.
     344-352.













































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