260 • Marine Minerals: Exploring Our New Ocean Frontier 



common depth point seismic reflection data for spe- 

 cific regions of the U.S. continental shelf, to core 

 descriptions for specizd areas, to high-resolution 

 seismic reflection data, to magnetic and gravity 

 data, to the latest data sets from the deep sea drilling 

 project, to ice-gouge data. These announcements 

 provide users with detailed information on the char- 

 acteristics of the particular data set being offered, 

 including related data sets, costs, and available 

 formats. 



The Marine Geology and Geophysics Division 

 has two interactive systems for accessing worldwide 

 marine geophysical data and geological data in the 

 sample holdings of the major U.S. core repositories. 

 Using software developed by the Division, a user 

 can specify geographic area, type of geophysical 

 measurement, sediment/rock type, geologic age, 

 etc., and receive inventory information at a com- 

 puter terminal. First operational in June 1978, these 

 two systems are used primarily by Division person- 

 nel, but there has been experimental use at remote 

 terminals by the staffs of Scripps Institution of 

 Oceanography and other core repositories under 

 data exchange agreements with NGDC and other 

 Federal agencies. NGDC hopes to make three other 

 data sets similarly accessible for users: 



1 . multi-beam echo-sounder data from NOS and 

 other collecting institutions, 



2. side-looking sonar data, and 



3. digital multi-channel seismic reflection data 

 if demand and funding warrant. 



NGDC staff states that most users of Division data 

 do not need "on-line"*' access; NGDC typically 

 satisfies most inquiries by performing tailored 

 searches of the data for the requestor. 



Types of FEZ data held by NGDC are Marine 

 Geological Data Bases, Bathymetry and Marine 

 Boundary Data Bases, and Underway Geophysi- 

 cal Data. In terms of numbers of reels of data stored 

 and in rates of acquisition in bytes*^ per year, the 

 Underway Geophysical Data sets dominate the 

 NGDC inventory (97 percent). Most of the data 

 sets are collected in digital form and stored on mag- 

 netic tape. 



''Interactive access to the data. 



*^One byte is the amount of computer memory used to store one 

 character of text. 



Marine Geological Databases. — There are four 

 major categories in the geological databases: Ma- 

 rine Core Curator's (MCC), Marine Minerals 

 (MM), Digital Grain Size (DGS), and Miscellane- 

 ous Geology Files (MGF). 



• All of the data sets are digital, aggregated, and 

 stored on magnetic tape except for the MGF. 

 The amount of MGF data stored is on 20 reels 

 of magnetic tape. The sum of the other cate- 

 gories is about 14x10^ bytes, half of which are 

 DGS data. All sets combined are on 23 reels 

 of magnetic tape. 



• The average delay between sampling and re- 

 porting is 10 years for DGS and MGF data 

 and 2 and 5 years respectively for MCC and 

 MM data. All four categories are provided on 

 request. 



• All data are acquired from academic or gov- 

 ernment laboratories ranging from 90 percent 

 academic for MCC to 90 percent government 

 for DGS. The sum of the acquisition rates for 

 MCC, MM, and DGS is about 140 kilobytes 

 per year (100 kilobytes per year for GDS) with 

 MGF acquiring about 1,000 stations per year. 



• Future uses are expected to increase by about 

 1 percent per year for MCC and GDS, 2 per- 

 cent per year for MM, and 5 percent per year 

 for MGF. 



Problems Handling Geological Data. — Marine 

 sediment and hard-rock analyses present unique 

 data management challenges. Unlike bathymetry, 

 for example, data volume presents no real obsta- 

 cle to geological data storage and retrieval. The 

 problem lies in the descriptive, free-form, non- 

 standard nature of the data. There are nearly limit- 

 less varieties of analyses performed on sediment and 

 hard-rock samples, each analysis requiring suitable 

 documentation to make the data usable. Decisions 

 must be made as to which types of analyses merit 

 creation of a database and, for each type of data 

 selected, which analyses or measurements should 

 be stored. These decisions require input from the 

 marine geological scientific community to be com- 

 bined with data management practices to produce 

 databases that satisfy user requirements. The non- 

 standard form of marine geological data also makes 

 compilation of data very labor-intensive. Much of 

 the data must be hand encoded from descriptive 

 data reports and other sources and entered into the 



