U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 06/14/1990
Station ID: 8656937 SUPERCEDED DATE: 04/21/2003
Name: CAPE LOOKOUT, ATLANTIC OCEAN
NORTH CAROLINA
NOAA Chart: 11545 Latitude: 34° 36.5' N
USGS Quad: CAPE LOOKOUT Longitude: 76° 31.7' W
To reach the tidal bench marks from Shell Point on Harkers Island, proceed by
boat SSW for about 4.6 statute miles (7.4 km) through Barden Inlet to the Cape
Lookout Lighthouse. The bench marks are about 0.8 mile (1.3 km) SSW of the
lighthouse, about 0.6 mile (0.9 km) NNE of the Coast Guard Station, and about
500 feet (152 m) SE of a line of utility poles. The tide gage and staff were SE
of Bench Mark 6937 A 1977, about 400 feet (122 m) seaward of the approximate low
water line.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6937 A 1977
MONUMENTATION: Survey Disk VM#: 3575
AGENCY: PID:
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is 321.4 feet (98.0 m) NE of Bench Mark 6937 B 1977, 180.0 feet
(154.9 m) WNW of the berm line, and 1.0 foot (0.3 m) west of a witness post.
The bench mark is 0.2 foot (0.1 m) above the ground, crimped to a galvanized
steel rod driven 64 feet (20 m) to refusal, and encased in a 4-inch PVC pipe and
concrete kickblock.
BENCH MARK STAMPING: 6937 B 1977
MONUMENTATION: Survey Disk VM#: 3576
AGENCY: PID:
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is 270.8 feet (82.5 m) south of Bench Mark 6937 C 1977, and 1.0
foot (0.3 m) west of a witness post. The bench mark is 0.2 foot (0.1 m) above
the ground, crimped to a galvanized steel rod driven 56 feet (17 m) to refusal,
and encased in a 4-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 06/14/1990
Station ID: 8656937 SUPERCEDED DATE: 04/21/2003
Name: CAPE LOOKOUT, ATLANTIC OCEAN
NORTH CAROLINA
NOAA Chart: 11545 Latitude: 34° 36.5' N
USGS Quad: CAPE LOOKOUT Longitude: 76° 31.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6937 C 1977
MONUMENTATION: Survey Disk VM#: 3577
AGENCY: PID:
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is 249.9 feet (76.2 m) SSW of Bench Mark 6937 D 1977, and 1.0
foot (0.3 m) west of a witness post. The bench mark is 0.2 foot (0.1 m) above
the ground, crimped to a galvanized steel rod driven 48 feet (15 m) to refusal,
and encased in a 4-inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 6937 D 1977
MONUMENTATION: Survey Disk VM#: 3578
AGENCY: PID:
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is 269.4 feet (82.1 m) SSW of Bench Mark 6937 E 1977, and 1.0
foot (0.3 m) west of a witness post. The bench mark is 0.2 foot (0.1 m) above
the ground, crimped to a galvanized steel rod driven 48 feet (15 m) to refusal,
and encased in a 4-inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 6937 E 1977
MONUMENTATION: Survey Disk VM#: 3579
AGENCY: PID:
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is 519 feet (158 m) SE of power pole #736 which is the 24th power
pole south of the lighthouse, 20 feet (6 m) south of the centerline of a 4-wheel
drive vehicle trail, and 1.0 foot (0.3 m) west of a witness post. The bench
mark is 0.2 foot (0.1 m) above the ground, crimped to a galvanized steel rod
driven 40 feet (12 m) to refusal, and encased in a 4-inch PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 06/14/1990
Station ID: 8656937 SUPERCEDED DATE: 04/21/2003
Name: CAPE LOOKOUT, ATLANTIC OCEAN
NORTH CAROLINA
NOAA Chart: 11545 Latitude: 34° 36.5' N
USGS Quad: CAPE LOOKOUT Longitude: 76° 31.7' W
T I D A L D A T U M S
Tidal datums at CAPE LOOKOUT, ATLANTIC OCEAN based on:
LENGTH OF SERIES: 8 MONTHS
TIME PERIOD: DECEMBER 1978-JULY 1979
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8656483 BEAUFORT
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (12/01/1978) = 5.60
MEAN HIGHER HIGH WATER MHHW = 3.84
MEAN HIGH WATER MHW = 3.51
MEAN TIDE LEVEL MTL = 1.87
MEAN LOW WATER MLW = 0.23
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (01/24/1979) = -1.50
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
6937 A 1977 7.35 3.84
6937 B 1977 6.17 2.66
6937 C 1977 5.69 2.18
6937 D 1977 5.67 2.16
6937 E 1977 6.31 2.80
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 06/14/1990
Station ID: 8656937 SUPERCEDED DATE: 04/21/2003
Name: CAPE LOOKOUT, ATLANTIC OCEAN
NORTH CAROLINA
NOAA Chart: 11545 Latitude: 34° 36.5' N
USGS Quad: CAPE LOOKOUT Longitude: 76° 31.7' W
D E F I N I T I O N S
Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal
Datum Epoch. It pertains to local mean sea level and should not be confused
with the fixed datums of North American Vertical Datum of 1988 (NAVD88).
NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum
constraint adjustment of Canadian/Mexican/United States leveling observations.
Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as
the single initial constraint. NAVD88 replaces NGVD29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD29 was originally derived from a general
adjustment of the first-order leveling networks of the U.S. and Canada after
holding mean sea level observed at 26 long term tide stations as fixed.
Numerous local and wide-spread adjustments have been made since establishment in
1929. Bench mark elevations relative to NGVD29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to
local MSL and other tidal datums may not be consistent from one location to
another.
The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique
identifiers for bench marks in the tidal and geodetic databases, respectively.
Each bench mark in either database has a single, unique VM# and/or PID# assigned.
Where both VM# and PID# are indicated, both tidal and geodetic elevations are
available for the bench mark listed.
The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD88 elevations.
The NAVD88 elevation relationship shown in the table is derived from an average
of several bench mark elevations relative to tide station datum. As a result of
this averaging, NAVD88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD88 elevations listed for
each bench mark in the NGS database.