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Details for Benchmark: NJ0547

N 42° 01.783 W 091° 42.783 (NAD 83)

Altitude: 811.57

Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)

Location:
In LINN county, IA View Original Datasheet
Designation:
Y 80
Marker Type:
bench mark disk
Setting:
abutments and piers of large bridges
Stability:
Probably hold position/elevation well.

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The abutment is being removed to make way for the Highway 100 extension. The concrete at the level of the disk has been removed. Appears destroyed.

This entry was edited by Bill93 on Wednesday, 09 April 2014 at 23:19:36 UTC.

[Photos:]
photoNJ0547_20140408_A.jpg
.
photoNJ0547_20140409_A.jpg
.

Found it at about 6:00. This benchmarking stuff is a bit harder than geocaching. I'm glad that I had Bill93's instructions.

[Photos:]
photoThe Benchmark
photoBe careful on the climb

Found in good condition at handheld coordinates N42 01.814 W091 42.798, sky half obstructed by nearby trees. Located about 3 feet north of the south end of abutment along Ushers Ferry Rd. Both railroads are torn out.

The climb up the embankment wasn't as bad as I expected, starting at the north end of the abutment. Be very aware of the unguarded dropoffs at the bottom as well as the top.

[This entry was edited by Bill93 on Thursday, October 14, 2004 at 7:36:35 PM.]

[Photos:]
photoNJ0547_20041003_A.jpg

Documented History (by the NGS)

01/01/1934 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1934 2.4 MI W FROM LOUISA. 2.4 MILES WEST ALONG THE CHICAGO, MILWAUKEE, ST. PAUL AND PACIFIC RAILROAD FROM THE STATION AT LOUISA, LINN COUNTY, 1 POLE WEST OF MILEPOST 233, AT THE UNDERPASS OF THE CHICAGO, ROCK ISLAND AND PACIFIC RAILWAY, IN THE TOP OF THE SOUTH END OF THE WEST CONCRETE ABUTMENT, 20 FEET SOUTH OF THE CENTERLINE OF THE TRACK, AND LEVEL WITH THE TRACK. A STANDARD DISK, STAMPED Y 80 1934.
03/30/1994 by USGS (GOOD)
RECOVERY NOTE BY US GEOLOGICAL SURVEY 1994 (RKL) RECOVERED AS DESCRIBED.

Control Text

  • The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in June 1991.
  • The geoid height was determined by GEOID99.
  • The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (g = 980.6199 gals.).
  • The modeled gravity was interpolated from observed gravity values.

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