U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8651538 PUBLICATION DATE: 02/08/2013
Name: FROG ISLAND
NC
NOAA Chart: 12205 Latitude: 36° 8.3' N ( 36.13858)
USGS Quad: WADE POINT, NC Longitude: 76° 6.3' W ( -76.10561)
To reach the bench marks from the intersection of Highway 17 (South Hughes
Boulevard) and North Carolina 344 (Halstead Boulevard) in Elizabeth City,
proceed south on North Carolina 344 (Halstead Boulevard) for 3.3 km, then
continue south on North Carolina 344 (Weeksville Road) for 11.2 km to the
intersection with North Carolina 344 (Salem Church Road). Turn left and proceed
south on North Carolina 344 (Salem Church Road) for 8.7 km to the intersection
with North Carolina 344 (Soundneck Road). Turn left onto North Carolina 344
(Soundneck Road) and proceed south for 2.4 km to the intersection with Frog
Island Road. Turn right onto Frog Island Road and proceed south for 2.7 km to
the end of Frog Island Road. The bench marks are located between the
intersection with Pine Shore Road and the end of Frog Island Road. The tide
gauge is located at the south bulkhead along the channel entrance.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1538 A 2012
DESIGNATION: 865 1538 A
MONUMENTATION: Flange-encased Rod VM#: 20439
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Flange-encased rod OPUS PID#: BBCS79
LATITUDE: 36° 8.3' N ( 36.13839) LONGITUDE: 76° 6.3' W ( -76.10519)
The primary bench mark is a flange-encased rod set in a grass and dirt area near
the seawall fronting on Albemarle Sound, 65.87 m (216.1 ft) southwest of the
southeast corner of the marina building, 22.89 m (75.1 ft) southwest of a power
pole with transformer number 25, 18.58 m (61.0 ft) west of the seaward corner of
a 60 degree bend in the seawall where it turns in towards land, 5.23 m (17.2 ft)
northeast of the seaward corner of a 30 degree bend in the sea wall and 0.61 m
(2.0 ft) northeast of an orange carsonite National Ocean Service witness post.
The datum point is set 7 cm (3 inches) below ground, being the top of a
stainless steel rod driven 20.6 m (67.6 ft) to refusal, in a sleeve extending to
a depth of 0.9 m (3.0 ft) and encased in a 5 inch (13 cm) National Ocean Service
logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8651538 PUBLICATION DATE: 02/08/2013
Name: FROG ISLAND
NC
NOAA Chart: 12205 Latitude: 36° 8.3' N ( 36.13858)
USGS Quad: WADE POINT, NC Longitude: 76° 6.3' W ( -76.10561)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1538 B 2012
DESIGNATION: 865 1538 B
MONUMENTATION: Survey disk VM#: 20440
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 36° 8.3' N ( 36.13883) LONGITUDE: 76° 6.3' W ( -76.10547)
The bench mark is a disk set in a covered concrete loading pad along the east
edge of the channel, 52.31 m (171.6 ft) northwest of bench mark 865 1538 A,
33.28 m (109.2 ft) northeast of the southwest corner of the sea wall, 11.99 m
(39.3 ft) southwest along the sea wall of the south side of a boat ramp, 0.41 m
(1.3 ft) southeast of the edge of the sea wall and 0.27 m (0.9 ft) southwest of
the northeast side of the concrete pad.
BENCH MARK STAMPING: 1538 C 2012
DESIGNATION: 865 1538 C
MONUMENTATION: Flange-encased Rod VM#: 20441
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Flange-encased rod OPUS PID:
LATITUDE: 36° 8.4' N ( 36.13997) LONGITUDE: 76° 6.2' W ( -76.10389)
The bench mark is a flange-encased rod set west of the road and the drainage
ditch and east of the treed portion of the lot, 58.62 m (192.3 ft) southwest of
a power pole with transformer number 8849 and light number 15, 13.75 m (45.1 ft)
west-northwest of the centerline of Frog Island Road, 5.87 m (19.3 ft) north of
a power pole, 2.55 m (8.4 ft) southeast of a 44 cm (17 inch) pine tree and 0.38
m (1.2 ft) southeast of an orange carsonite National Ocean Service witness post.
The datum point is set 9 cm (4 inches) below ground, being the top of a
stainless steel rod driven 24.0 m (78.7 ft) to refusal, in a sleeve extending to
a depth of 0.9 m (3.0 ft) and encased in a 5 inch (13 cm) National Ocean Service
logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8651538 PUBLICATION DATE: 02/08/2013
Name: FROG ISLAND
NC
NOAA Chart: 12205 Latitude: 36° 8.3' N ( 36.13858)
USGS Quad: WADE POINT, NC Longitude: 76° 6.3' W ( -76.10561)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: FROG ISLAND 1931
DESIGNATION: FROG ISLAND AZ MK 22
MONUMENTATION: Survey disk VM#: 20442
AGENCY: NOS IDB PID#: FX3716
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 36° 8.5' N ( 36.14217) LONGITUDE: 76° 6.1' W ( -76.10228)
The bench mark is a standard NGS azimuth mark disk set in the top of a 12 inch
concrete cylinder, flush with the ground, 26.52 m (87.0 ft) NE of a power pole
with transformer and reference tag, 15.54 m (51.0 ft) NW of centerline of SR
1107, 6.71 m (22.0 ft) SW of centerline of SR 1209, 3.81 m (12.5 ft) north of a
telephone pedestal, 3.23 m (10.6 ft) NNW of a power pole with reference tag, and
0.34 m (1.1 ft) SE of a witness post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8651538 PUBLICATION DATE: 02/08/2013
Name: FROG ISLAND
NC
NOAA Chart: 12205 Latitude: 36° 8.3' N ( 36.13858)
USGS Quad: WADE POINT, NC Longitude: 76° 6.3' W ( -76.10561)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: FROG IS.
DESIGNATION: FROG ISLAND
MONUMENTATION: Survey disk VM#: 20443
AGENCY: USC&GS IDB PID#: FX3693
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 36° 8.3' N ( 36.13869) LONGITUDE: 76° 6.3' W ( -76.10453)
The bench mark is a standard USCGS disk set in a square concrete monument, 18.29
m (60.0 ft) NE of the pier leading to a small gray house, 9.45 m (31.0 ft) east
of the approximate center of the road, and 9.08 m (29.8 ft) SW of the
northernmost gate post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8651538 PUBLICATION DATE: 02/08/2013
Name: FROG ISLAND
NC
NOAA Chart: 12205 Latitude: 36° 8.3' N ( 36.13858)
USGS Quad: WADE POINT, NC Longitude: 76° 6.3' W ( -76.10561)
T I D A L D A T U M S
Tidal datums at FROG ISLAND based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: May 2012 - July 2012
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8652587 OREGON INLET MARINA, PAMLICO SOUND
Elevations of tidal datums referred to Mean Sea Level (MSL), in METERS:
MEAN SEA LEVEL MSL = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MSL
1538 A 2012 0.867
1538 B 2012 0.581
1538 C 2012 0.417
FROG ISLAND 1931 0.578
FROG IS. 0.278
Foot Notes:
This station has been determined to be Non-tidal for tidal datum purposes.There
is either no measureable periodic rise and fall of the tide at thislocation, or
it may be present but inconsistent, or the periodic tide ispresent and
consistent, however the Mean Range of Tide (MN) is negligible,that is below the
established tidal/non-tidal threshold of 0.03m (0.10ft).Only the datum of local
Mean Sea Level (MSL) is published at these stations.For Nautical Charting Datum
applications, a non-tidal Low Water Datum (LWD)is established as 0.50ft (0.15m)
below MSL.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8651538 PUBLICATION DATE: 02/08/2013
Name: FROG ISLAND
NC
NOAA Chart: 12205 Latitude: 36° 8.3' N ( 36.13858)
USGS Quad: WADE POINT, NC Longitude: 76° 6.3' W ( -76.10561)
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 NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.
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.