The Marine Trackline Geophysical Database contains bathymetric, magnetic, gravity and digital shot-point navigation data collected during marine surveys from 1939 to the present. Coverage is worldwide and new data are continually being added. Data sources include both U.S. and foreign oceanographic organizations. NGDC's digital marine trackline geophysical data holdings have been released as a CD/DVD data set by NGDC's Marine Geology and Geophysics Division, complete with PC-compatible search and retrieval software for Microsoft Windows 95/98/NT as well as UNIX Xwindows. Data are stored in the MGD77 Data Exchange Format. Each ASCII header file contains 24 80-character records, each containing specific fields. Each ASCII data file contains a series of 120-character data records for a particular cruise/leg (port to port operation).
Although not included on the CD/DVD, NGDC also makes available: (a) full resolution digital multibeam bathymetry data, (b) digital seismic data and (c) analog underway geophysical data including seismic reflection and refraction, side-scan sonar, and other data types. The digital multibeam data, digital seismic data and analog data are inventoried and searchable through GEODAS and copies are available from NGDC (contact NGDC for additional information).