Grand Canyon Survey 1971 – 75 Station Types

There are 92 control points in this survey

75 of them were fixed by both laser and theodolite (see attached list)

7 of them were occupied by theodolite and sighted by theodolite from one or more other stations: (2) Boulder (5) Colonnade (9) Cremation (11) Data (22) Horus (55) Phantom USGS (85) Tonto

8 were targeted by helicopter and fixed by triangulation from two or more points: (7) Cope (15) Grama (33) Johnson (45) Newton (51) Pattie (47) O’Neill (52) Perch (72) Set A

2 were not visited at all and their peaks were intersected from two or more points: (32) Isis (48) Osiris

The altitudes of 12 stations were determined by leveling:

From USG & GS Bench Mark S-61 (6876.164 ft.)
(20) Hopi (44) Middle (USC & GS), also (41) Maricopa (42) Maricopa A

From USGS Bench Mark 3870.292 ft. on Bright Angel Trail
(24) Indian Gardens (65) Plateau Point

From USNPS Pipeline level line
(54) Phantom Ranch (55) Phantom USGS

Two USC & GS stations were occupied with both theodolite and laser:
(44) Middle (81) Sublime

Three USGS stations were occupied with both theodolite and laser:
(46) Obi (67) Powell Pt. (70) Rowe