U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 11/08/2000
Station ID: 8573704 SUPERCEDED DATE: 04/21/2003
Name: BETTERTON, SASSAFRAS RIVER
MARYLAND
NOAA Chart: 12274 Latitude: 39° 22.3' N
USGS Quad: BETTERTON Longitude: 76° 3.8' W
To reach the tidal bench marks from the intersection of Route 291 and Route 213
in Chesterton, travel 6.2 km (3.7 mi) north on Route 213 to Route 561, turn left
and proceed 3.9 km (2.4 mi) to Route 298 in Lynch, turn left and proceed 1.6
miles (2.6 km) to Route 292, turn left and proceed to the T, turn left again
staying on Route 292 to its end. The bench marks are located along Route 292.
The tide gage and staff were located on the Kent County Public Pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 4 1938
DESIGNATION: TIDAL 4 STA 59
MONUMENTATION: Tidal Station disk VM#: 3162
AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: JV0549
SETTING CLASSIFICATION: Concrete support
The primary bench mark is a disk set vertically in the north face of a concrete
support for the concrete steps leading uphill to the entrance on the north side
of Rigbie Hotel, 33 m (108 ft) east of the NE corner of the post office, 10.67 m
(35.0 ft) east of the centerline of Main Street, 3.20 m (10.5 ft) south of the
extended centerline of Ericsson Avenue, and 0.43 m (1.4 ft) above ground.
BENCH MARK STAMPING: NO 6 1971
DESIGNATION: 857 3704 NO 6
MONUMENTATION: Bench Mark disk VM#: 3163
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Concrete pad
The bench mark is a disk set in a cement pad on the side of the pumphouse,
located on the west side of a pump house at the east end of a parking lot east
of Main Street at the foot of a hill, 11.58 m (38.0 ft) NE of a power pole at
the SE corner of the lot,10.67 m (35.0 ft) east of the east end of the parking
lot pavement, 1.98 m (6.5 ft) SW of the NW corner of the pump house, and 0.46 m
(1.5 ft) ENE of a witness post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 11/08/2000
Station ID: 8573704 SUPERCEDED DATE: 04/21/2003
Name: BETTERTON, SASSAFRAS RIVER
MARYLAND
NOAA Chart: 12274 Latitude: 39° 22.3' N
USGS Quad: BETTERTON Longitude: 76° 3.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 7 1971
DESIGNATION: 857 3704 NO 7
MONUMENTATION: Bench Mark disk VM#: 3164
AGENCY: US Coast and Geodetic Survey (USC&GS) PID:
SETTING CLASSIFICATION: Retaining wall
The bench mark is a disk set flush in the top of the south end of a retaining
wall on the west side of Main Street, 37.73 m (123.8 ft) south of the north end
of the retaining wall, 16.37 m (53.7 ft) south of the south retaining wall for
steps in the main retaining wall, 10.03 m (32.9 ft) NW of power pole 33999
29830, 4.48 m (14.7 ft) west of the centerline of Main Street, and 0.46 m (1.5
ft) north of the south end of the retaining wall.
BENCH MARK STAMPING: 3704 A 1999
DESIGNATION: 857 3704 A
MONUMENTATION: Tidal Station disk VM#: 15889
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Flagpole foundation
The bench mark is a disk set in a foundation for three flag poles, just south of
the south side of Ericson Avenue, 17.98 m (59.0 ft) west of a fire hydrant,
11.81 m (38.8 ft) south of the centerline of Ericson Avenue, 5.15 m (16.9 ft)
east of the west end of the concrete foundation, and 0.12 m (0.4 ft) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 11/08/2000
Station ID: 8573704 SUPERCEDED DATE: 04/21/2003
Name: BETTERTON, SASSAFRAS RIVER
MARYLAND
NOAA Chart: 12274 Latitude: 39° 22.3' N
USGS Quad: BETTERTON Longitude: 76° 3.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3704 B 1999
DESIGNATION: 857 3704 B
MONUMENTATION: Tidal Station disk VM#: 15890
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Picnic shelter slab
The bench mark is a disk set in the concrete slab foundation for the picnic
shelter on a hill overlooking the beach at Betterton, 16.43 m (53.9 ft) west of
a light pole, 12.07 m (39.6 ft) east of the western edge of the foundation, 5.03
m (16.5 ft) north of the south edge of the foundation, and 3.15 m (10.3 ft)
south of the north edge of the foundation.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 11/08/2000
Station ID: 8573704 SUPERCEDED DATE: 04/21/2003
Name: BETTERTON, SASSAFRAS RIVER
MARYLAND
NOAA Chart: 12274 Latitude: 39° 22.3' N
USGS Quad: BETTERTON Longitude: 76° 3.8' W
T I D A L D A T U M S
Tidal datums at BETTERTON, SASSAFRAS RIVER based on:
LENGTH OF SERIES: 7 MONTHS
TIME PERIOD: June 1999 - December 1999
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8574680 BALTIMORE, FORT MCHENRY, PATAPSCO RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.657
MEAN HIGH WATER MHW = 0.549
North American Vertical Datum NAVD88 = 0.371
MEAN SEA LEVEL MSL = 0.321
MEAN TIDE LEVEL MTL = 0.312
MEAN LOW WATER MLW = 0.075
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 4 1938 5.338 4.789
NO 6 1971 2.235 1.686
NO 7 1971 11.639 11.090
3704 A 1999 3.911 3.362
3704 B 1999 12.693 12.144
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 11/08/2000
Station ID: 8573704 SUPERCEDED DATE: 04/21/2003
Name: BETTERTON, SASSAFRAS RIVER
MARYLAND
NOAA Chart: 12274 Latitude: 39° 22.3' N
USGS Quad: BETTERTON Longitude: 76° 3.8' 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.