Walking past the Fred Moore School with it’s great (sanctioned) graffiti:
I looked down and noticed, stuck in the concrete of a window well, a geodetic bench mark from the US Coast and Geodetic Survey:
Locating a survey marker in a window well seemed a poor choice, given that the wall of the school restricted visibility from the marker to just over 180 degrees, and also that plantings between the window well and the school fence were likely to result in roots that could crack the concrete.
Sure enough, a closer look at the marker shows a number of cracks that would likely render the marker ‘good enough’ but certainly not down to the millimeter.
As you can see from the photo above, the marker was placed there a few years after the school was built (1949), and while the marker has space for noting the elevation above sea level, that part of the bronze marker is unmarked.
To learn more you need to go to this site:
https://geodesy.noaa.gov/datasheets/
where you can find the markers closest to wherever you are in the US. Looking at northern Manhattan, you can see that there are a few around, mostly near the water:
The one I’d stumbled across is listed here:
has its own data sheet that tells more about its location, height, and even that accuracy is sketchy
https://geodesy.noaa.gov/datasheets/
The gist might be that it’s about 6.7m or 22 feet above sea level
To learn more about Fred Moore, see:
https://www.nycgovparks.org/parks/moore-playground/history
PROGRAM = datasheet95, VERSION = 8.12.5.14 Starting Datasheet Retrieval... 1 National Geodetic Survey, Retrieval Date = DECEMBER 29, 2021 KU1032 *********************************************************************** KU1032 DESIGNATION - V 338 KU1032 PID - KU1032 KU1032 STATE/COUNTY- NY/NEW YORK KU1032 COUNTRY - US KU1032 USGS QUAD - CENTRAL PARK (2019) KU1032 KU1032 *CURRENT SURVEY CONTROL KU1032 ______________________________________________________________________ KU1032* NAD 83(1986) POSITION- 40 48 35. (N) 073 56 22. (W) SCALED KU1032* NAVD 88 ORTHO HEIGHT - 6.775 (meters) 22.23 (feet) ADJUSTED KU1032 ______________________________________________________________________ KU1032 GEOID HEIGHT - -31.556 (meters) GEOID18 KU1032 DYNAMIC HEIGHT - 6.772 (meters) 22.22 (feet) COMP KU1032 MODELED GRAVITY - 980,258.2 (mgal) NAVD 88 KU1032 KU1032 VERT ORDER - FIRST CLASS II KU1032 KU1032.The horizontal coordinates were scaled from a map and have KU1032.an estimated accuracy of +/- 6 seconds. KU1032. KU1032.The orthometric height was determined by differential leveling and KU1032.adjusted by the NATIONAL GEODETIC SURVEY KU1032.in June 1991. KU1032 KU1032.Significant digits in the geoid height do not necessarily reflect accuracy. KU1032.GEOID18 height accuracy estimate available here. KU1032 KU1032.Click photographs - Photos may exist for this station. KU1032 KU1032.The dynamic height is computed by dividing the NAVD 88 KU1032.geopotential number by the normal gravity value computed on the KU1032.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 KU1032.degrees latitude (g = 980.6199 gals.). KU1032 KU1032.The modeled gravity was interpolated from observed gravity values. KU1032 KU1032; North East Units Estimated Accuracy KU1032;SPC NY L - 71,410. 305,110. MT (+/- 180 meters Scaled) KU1032 KU1032_U.S. NATIONAL GRID SPATIAL ADDRESS: 18TWL894181(NAD 83) KU1032 KU1032 SUPERSEDED SURVEY CONTROL KU1032 KU1032 NGVD 29 (??/??/92) 7.104 (m) 23.31 (f) ADJ UNCH 1 2 KU1032 KU1032.Superseded values are not recommended for survey control. KU1032 KU1032.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums. KU1032.See file dsdata.pdf to determine how the superseded data were derived. KU1032 KU1032_MARKER: DB = BENCH MARK DISK KU1032_SETTING: 32 = SET IN A RETAINING WALL OR CONCRETE LEDGE KU1032_SP_SET: RETAINING WALL KU1032_STAMPING: V 338 1952 KU1032_MARK LOGO: CGS KU1032_STABILITY: C = MAY HOLD, BUT OF TYPE COMMONLY SUBJECT TO KU1032+STABILITY: SURFACE MOTION KU1032 KU1032 HISTORY - Date Condition Report By KU1032 HISTORY - 1952 MONUMENTED CGS KU1032 HISTORY - 20031216 GOOD INDIV KU1032 KU1032 STATION DESCRIPTION KU1032 KU1032'DESCRIBED BY COAST AND GEODETIC SURVEY 1952 KU1032'AT NEW YORK. KU1032'AT NEW YORK, IN BOROUGH OF MANHATTAN, AT INTERSECTION OF 5TH KU1032'AVENUE AND EAST 131ST STREET, 33 FEET SOUTHEAST OF SOUTHEAST CURB KU1032'OF 5TH AVENUE, 100 1/2 FEET SOUTHWEST OF SOUTHWEST CURB OF EAST KU1032'131ST STREET, IN THE TOP OF NORTH CORNER OF RETAINING WALL OF AIR KU1032'SHAFT FOR BASEMENT WINDOW OF PUBLIC SCHOOL NO. 133 (FRED R. MOORE KU1032'SCHOOL), 8.4 FEET SOUTHWEST OF CENTER OF ENTRANCE TO SCHOOL AND KU1032'ABOUT 0.4 FOOT ABOVE SIDE WALK. KU1032 KU1032 STATION RECOVERY (2003) KU1032 KU1032'RECOVERY NOTE BY INDIVIDUAL CONTRIBUTORS 2003 (DS) KU1032'RECOVERED IN GOOD CONDITION.
Harlem Library
Here is a second, US Coast and Geodetic Survey, found in Harlem (built into the Harlem Library, next to Marcus Garvey Park.
Harlem Residents Protest Property Taxes While Being Oversaturated
To sign the petition to end the oversaturation of Harlem and East Harlem, see: