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 ¯20

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:  ¯IPD15120.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯131405428
   traces in file:  ¯24137
      first trace:  ¯1/42 FFID/trace
       last trace:  ¯504/34 FFID/trace


             file:  ¯IPD15371.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯132058708
   traces in file:  ¯24257
      first trace:  ¯504/35 FFID/trace
       last trace:  ¯10/3 FFID/trace


             file:  ¯IPD15624.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯131389096
   traces in file:  ¯24134
      first trace:  ¯10/4 FFID/trace
       last trace:  ¯512/41 FFID/trace

                              1
 
             file:  ¯IPD15875.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯131960716
   traces in file:  ¯24239
      first trace:  ¯512/42 FFID/trace
       last trace:  ¯17/40 FFID/trace


             file:  ¯IPD16128.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯63284656
   traces in file:  ¯11624
      first trace:  ¯17/41 FFID/trace
       last trace:  ¯259/48 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.

OB15100
OB15150
OB15200
OB15250
OB15300
OB15350
OB15400
OB15450
OB15500
OB15550
OB15600
OB15650
OB15700
OB15750
OB15800
OB15850
OB15900
OB15950
OB16000
OB16050
OB16100
OB16150
OB16200


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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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