Data Center provides GeoData in SDTS format free for download from the World Wide Web. Below are explanations and examples of each type of GeoData.
Elevations are in meters relative to mean sea level.
Spacing of the elevations along and between each profile is 3 arc- seconds with 1,201 elevations per profile. Where 7.5-minute coverage was not available, other sources were used. The unit sizes in Alaska vary depending on the latitudinal location of the unit. The spacing between elevations along profiles is 1 arc second in latitude by 2 arc seconds of longitude. Of the three file levels, the DLG-3 files are the only files that are distributed to the user community.