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Details for Benchmark: NJ0582

N 42° 01.117 W 091° 43.233 (NAD 83)

Altitude: 752.93

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

Location:
In LINN county, IA View Original Datasheet
Designation:
Y 75
Marker Type:
bench mark disk
Setting:
set into the top of a round concrete monument
Stability:
May hold, but of type commonly subject to surface motion.

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Though I am new to the becnchmark game, I feel confident that I located the cement post with the disk missing/destroyed. Based on my information, it has been recommended by those more learned than I to log as such.
Located remains of post at N42 01.140, W091 43.239 (Garmin 60CSX, WAAS enabled, 4 multiple readings, on two days averaged), 140' N of the published coordinates. Post stands approx. 6" above present grade in grass area to the east of existing rails. Branchline in the 1934 description has been removed. Remains of post is 17' at 60 degrees ENE of the centerline of the existing main rail line. 22' at 150 degrees SSE from the east semaphore(of two semaphores)base. Post appears to have been split in two and disk removed.

[Photos:]
photoView Looking South to area of benchmark NJ0582
photoClose view of believed remains of benchmark NJ0582

Documented History (by the NGS)

01/01/1934 by CGS (MONUMENTED)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1934 AT LINN. AT LINN, LINN COUNTY, ON THE CHICAGO, ROCK ISLAND AND PACIFIC RAILWAY, 33 POLES NORTH OF MILEPOST 101, 85 YARDS NORTH OF THE CENTER OF THE JUNCTION OF A CHICAGO, ROCK ISLAND AND PACIFIC RAILWAY MAIN LINE, 15 FEET WEST OF THE CENTERLINE OF THE BRANCH LINE, 14 FEET EAST OF THE CENTERLINE OF THE MAIN TRACK, 20 FEET SOUTHWEST OF THE SEMAPHORE SIGNAL, AND LEVEL WITH THE TRACK. A STANDARD DISK, STAMPED Y 75 1934 AND SET IN THE TOP OF A CONCRETE POST.
01/01/1934 by NGS (GOOD)

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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