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 ¯17

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:  ¯IPD12074.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯128552772
   traces in file:  ¯23613
      first trace:  ¯910/32FFID/trace
       last trace:  ¯402/28 FFID/trace


             file:  ¯IPD12320.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯128906632
   traces in file:  ¯23678
      first trace:  ¯402/29 FFID/trace
       last trace:  ¯895/42 FFID/trace


             file:  ¯IPD12567.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯132227472
   traces in file:  ¯24288
      first trace:  ¯895/43 FFID/trace
       last trace:  ¯402/42 FFID/trace

                             1

             file:  ¯IPD12820.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯7353000
   traces in file:  ¯1350
      first trace:  ¯402/43 FFID/trace
       last trace:  ¯430/48 FFID/trace


             file:  ¯IPD12835.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1551
      data length:  ¯6204 msec
  bytes per trace:  ¯6444
    bytes in file:  ¯137698992
   traces in file:  ¯21368
      first trace:  ¯431/1 FFID/trace
       last trace:  ¯876/8 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.

OB12070
OB12100
OB12100G
OB12150
OB12200
OB12250
OB12300
OB12350
OB12400
OB12450
OB12500
OB12550
OB12600
OB12650
OB12700
OB12750
OB12800
OB12850
OB12900
OB12950
OB13000
OB13050

                             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.





































                             3