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 ¯18

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:  ¯IPD13057.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1551
      data length:  ¯6204 msec
  bytes per trace:  ¯6444
    bytes in file:  ¯136700172
   traces in file:  ¯21213
      first trace:  ¯876/9 FFID/trace
       last trace:  ¯319/5 FFID/trace


             file:  ¯IPD13279.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1551
      data length:  ¯6204 msec
  bytes per trace:  ¯6444
    bytes in file:  ¯137692548
   traces in file:  ¯21367
      first trace:  ¯319/6 FFID/trace
       last trace:  ¯764/12 FFID/trace


             file:  ¯IPD13501.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1551
      data length:  ¯6204 msec
  bytes per trace:  ¯6444
    bytes in file:  ¯136732392
   traces in file:  ¯21218
      first trace:  ¯764/13 FFID/trace
       last trace:  ¯206/14 FFID/trace

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             file:  ¯IPD13722.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1551
      data length:  ¯6204 msec
  bytes per trace:  ¯6444
    bytes in file:  ¯137286576
   traces in file:  ¯21304
      first trace:  ¯206/15 FFID/trace
       last trace:  ¯650/6 FFID/trace


             file:  ¯IPD13944.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1551
      data length:  ¯6204 msec
  bytes per trace:  ¯6444
    bytes in file:  ¯103584456
   traces in file:  ¯16074
      first trace:  ¯650/7 FFID/trace
       last trace:  ¯984/48 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 for the file names given below.

OB13050
OB13100
OB13150
OB13200
OB13250
OB13300
OB13350
OB13400
OB13450
OB13500
OB13550
OB13600
OB13650
OB13700
OB13750
OB13800
OB13850
OB13900
OB13950
OB14000
OB14050
OB14100



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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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