M258

ALTERNATE NAME/NUMBER - Mile 258

76º 03' 22" S

116º 57' 12" W

1580 Meters

BYRD STATION TRAVERSE

1959-60 Season

Engineer: William H. Chapman

Solar position at Mile 258 is the horizontal datum used to determine the horizontal positions for selected intersected map control points on Toney Mountain, Mount Murphy, Crary Mountains, and Mount Takahe (Adjusted to Marie Byrd Land Electronic Traverse of 1966-67-68).

Elevations determined by altimeter traverse based on Byrd Station elevation of 1530 meters. (The altimetry elevations have been adjusted to agree with the elevations determined from the Marie Byrd Land Electronic Traverse of 1966-67-68).

Wild T-2 used for angular measurements.

Located approximately 80 km N of summit of Creary Mountains and 43 km SW of summit of Toney Mountain.

Station mark - unmonumented snow station. Not photo-identifiable.

Surveyed 1959-60.

Horizontal Datum - Position based on the Astronomic Position of M258.

Vertical Datum - Mean sea level.

BYRD STATION 1959-1960 TRAVERSE

Traverse starts and ends at Byrd Station elevation 1530. Stations spaced 3 nautical miles apart to Mile 998, then 5 statue miles to Byrd Station. Stations designated by numbers from Mile 0 to Mile 998 represent the number of nautical miles traveled from Byrd Station. From Mile 998 to Byrd Station, the stations are designated by numbers given by the Army-Navy Drive Traverse. Mile 390.5 is a tie to sea-level by triangulation on water-line of icebergs. Miles 258, 603, 711.5, and 890 are tied to the Marie Byrd Land Electronic Traverse of 1966-67-68 field seasons. The Marie Byrd Land Electronic Traverse was tied to sea-level by triangulation from the Alexander Mountains in the Edward VII Peninsula area, Grant Island on the western end of the Getz Ice Shelf and Wright Island on the eastern end of the Getz Ice Shelf. The altimeter elevations have been adjusted to agree with the elevations determined from the electronic traverse at the above stated points.